OSTEOBLASTOMA Definition: - Benign bone forming neoplasm producing woven bone spicules bordered by prominent osteoblasts (osteoid osteoma measuring more than 2.0 cm) Epdemiology: - About 1% of bone tumors - Age: 10-30 y/o ( male teenagers) - Male:Female ratio 2.5:1, Sites of involvement: - Predilection for the spine (40-55% of cases) - Other common sites femur and proximal tibia - Cementoblastoma of jaw is considered osteoblastoma and is attached to the root of tooth. Clinical findings: - Osteoblastoma of spine may cause back pain, scoliosis and nerve root compression. - Jaw lesion may produce tooth pain. - Aspirin does not relieve pain after long therapy. Imaging: - Lytic well circumscribed oval or round defect - Almost always confined by a periosteal shell of reactive bone. Gross: - Red or red brown (vascular). - Often with gritty or sandpaper consistency. Histopathology: - Composed of woven bone spicules or trabeculae lined by a single layer of osteoblasts. - Stromal rich vascularity. - Scattered osteoclast-type multinucleated giant cells are often present. - Focal blood filled spaces mimicking Aneurysmal Bone Cyst (ABC) may be present. - Osteoblastomas do not infiltrate and isolate pre-existing lamellar bone structures as does osteosarcoma. Prognosis: - Excellent - Recurrences unusual if well excisded
SIMPLE (UNICAMERAL ) BONE CYST (UBC) Definition: - Intramedullary, usually unilocular, bone cyst filled with serous or sero-sanguineous fluid. Epidemiology: - 85% of patients in the first decades of life. - Male:Female ratio 3:1. Sites of involvement: Most common locations: - proximal humerus - proximal femur - proximal tibia Clinical findings: - Pain and swelling. - Patients may present with pathological fracture. Imaging: - Typically begins in the metaphysis and extends into the diaphysis. Gross: - Fragments of thin whitish membrane - Usually during surgery you get scant tissue material. Histopathology: - Cyst wall consist of a thin layer of fibrous tissue composed of scattered fibroblasts and collagen fibers,. - No cell lining of cystic internal surface. - Pathologic fractures may cause reactive changes and show numerous reactive fibroblasts, osteoclast type giant cells, hemosiderin deposists and reactive woven bone. Genetics: - Rearrangements involving chromosomes 4, 6, 8, 16, 21. Prognosis: - Recurrence is reported at 10-20% of cases, especially in children. - Growth arrest of the affected bone and avascular necrosis of the head of the femur after pathological fracture can occur
ANEURYSMAL BONE CYST (ABC) Definition: - Benign multiloculated , blood-filled cystic mass that is often expansile and destructive. Epidemiology: - Affects all age groups but generally occurs during the first two decades of life (median age approximately 13 years). - No sex predilection. Sites of involvement: - May affect any bone. - Usually arise in the metaphysis of long bone especially the femur, tibia and humerus. Clinical findings: - Pain and swelling which may be secondary to fracture. Imaging: - Usually eccentric, expansile lesion with well defined margins. - Most lesions are completely lytic and often contain a thin shell of reactive bone at the periphery. - CT and MRI may demonstrate internal septa and characteristic fluid-fluid level. Gross: - Well-defined sponge-like mass. - Composed of multiple, blood filled spaces separated by thin, tan-white septa. Histopathology: - Walls of ABC consist of plump uniform fibroblaststs ( which may be mitotically active), multinucleated osteoclast-like giant cells ( sometimes they look like jumping into swimming pool cystic spaces), and thin trabeculae of reactive woven bone. - Surface of reactive woven bone is lined by plump osteoblasts. - 1/3 of cases contain a cartilage-like matrix, called 'blue bone', which is not common in other bone lesions. - Necrosis is uncommon unless there has been a previous pathologic fracture. Genetics: Prognosis: - Recurrence rate following curretage is variable (20-70%). - Primary aneurysmal bone cysts account for approximately 70% of all cases. - Majority of secondary ABC arise in association with benign neoplasms, most commonly giant cell tumor of bone (GCT), chondroblastoma, osteoblastoma, and fibrous dysplasia, and less frequently, osteosarcoma.
FIBROUS DYSPLASIA Definition: - Benign medullary fibro-osseous lesion which may involve one (monostotic) or more bones (polyostotic). Epidemiology: - Children and adults - Monostotic solitary lesion most common 70-80% - No sex predilection. Sites of involvement: - Gnathic (jaw) bones most common - Long bones are more often involved in woman - Ribs and skull are favored sites for man. - Monostotic form, about 35% involve the head, 1/3 tibia and femur, and rest 20% ribs. - Polyoostotic form, the femur, pelvis and tibia are more common involved Clinical findings: - Fibrous dysplasia may present in monostotic or polyostotic form. - Polyostotic form can be confined to one extremity or one side of the body or be diffuse. - Polyostotic form often manifest earlier in life than the monostotic form. - FD is often asymptomatic but pain and fractures may be part of clinical spectrum. - FD may be associated with oncogenic osteomalacia. - FD may be associated with McCune-Albright syndrome, in which there are endocrine abnormalities and skin pigmentation. Imaging: - Non agressive geographical lesion with a ground glass matrix. - In the appendicular skeleton, the margins are usually well defined and surrounded by a rim of sclerotic bone. - FD in the craniofacial skeleton seems to be less well defined and blends with surrounding bone. Gross: - Well circumscribed - Gritty and leather-like consistency. Histopathology: - Composed of cellular fibrous tissue surrounding irregular, curvilinear bony trabeculae. - The bony trabeculae are discontinuous and are composed of woven bone that is formed directly from the spindle cells with minimal osteoblastic rimming. - In craniofacial tumors, the lesional bone tends to fuse with the surrounding host cancellous bone, explaining the lack of demarcation radiographically. - The spindle cells may be arranged in a storiform pattern, and may be associated with collectioon of foamy macrophages mimicking a xanthoma or fibroxanthoma. - Collagen fibers (Sharpey-like fibers) are frquently seen extending from the fibrous tissue ibnto the lesional bone. - Cystic changes mimicking ABC are occasionally encountered. Genetics: - Mutation of the G protein (guanine nucleotide-binding protein). Prognosis: - Good. - Therapy ranges from observation to surgical removal.
OSTEOFIBROUS DYSPLASIA Definition: - Self-limited benign fibro-osseous lesion of bone. - Involving cortical bone of the anterior mid-shaft of the tibia during infancy and childhood. Epidemiology: - Rare tumor that accounts for less than 1% of all bone tumors. - Commonly seen in boys during the first two decades of life with precipitous drop-off thereafter. Sites of involvement: - Proximal or middle-third of the tibia is the most frequent (90%) - Less common sites are ulna and radius. Clinical findings: - Rare after the age of 15. - Most common presenting symptoms are swelling or painless deforming (bowing) of the involved segment of the limb. Imaging: - Well-delineated, intracortical lucency, surrounded by areas of sclerosis. - May form as a single lytic lesion, but more commonly forms confluent oval-shaped, scalloped, saw-toothed or bubbly multiloculated lytic lesions in cortex. Gross: - Varies in size from <1 cm to >10cm. - Typically solid, yellow or white and gritty, and confined to the cortex, which is expanded and attenuated. Histopathology: - Composed of irregular curvilinear trabeculae of woven bone that at the periphery merge with pre-existing cancellous bone. - Trabeculae of woven bone are rimmed by prominent osteoblasts and scattered osteoclasts may be seen. - intervening stroma is composed of benign appearing spindle-shaped cells embedded in a collagenous matrix. - Isolate single stromal cells may express keratin; however, clusters of epithelial cells, as seen in well differentiated adamantinoma are absent. Immunohistochemistry: - Positive for vimentin, occasionally S100 and Leu7. Genetics: - Trisomy 7 and 8 have been demonstrated. Prognosis: - Natural history of osteofibrous dysplasia is that of gradual growth during the first decade of life with stabilization at about 15 years of age resolution. - Progression of OFD-like adamantinoma to classic adamantinoma has been shown in few patients.
FIBROUS CORTICAL DEFECT/NON-OSSIFYING FIBROMA Definition: - Benign lesion of bone composed of spindle-shaped fibroblasts, arranged in a storiform pattern, with a variable admixture of multinucleated osteoclast-like giant cells. - Foamy cells (xanthoma), chronic inflammatory cells and hemosiderin may be present - The name fibrous cortical defect is used when the lesion is confined to the cortex; however if becomes large enough to extend into adjacent medullary cavity than the term non-ossifying fibroma is used. Epidemiology: - Patient have ranged in age from 6 to 74 years old. 30-40% in children. - An average age of 4 years 54% of boys and 22% of girls, had a lesion involving the cortex, and most regressed spontaneously over a period of approximately 2.5 years. Site of involvement: - Approximately 40% of NOF occur in the long bones, with distal femur, distal and proximal tibia most frequently involved. - As many as 25% of cases involve the pelvic bone, in particular the ilium. Clinical findings: - Majority of NOF cases are asymptomatic, and are an incidental discovery on X-rays performed for other reasons. - Larger lesion may cause pain that is probably secondary to microfractures or obvious pathologic fracture. - Most pathologic fractures develop through lesions that involve more than 50% of the diameter of the bone. - The vast majority of NOF are single, although thay are multiple in 8% of cases. - Multiple NOF may be associated with syndromes such as neurofibromatosis and Jaffe-Campanacci syndrome. Imaging: - Eccentric, lytic lesions centered within the metaphyseal cortex and adjacent medullary cavity of long tubular bones. - Well demarcated with sclerotic margins and frequently harbor internal trabeculation. Gross: - Eccentric, well circumscribed and have sclerotic borders. - The overlying cortex is thinned and may be completely eroded. - The lesions are tan brown and frequently have areas that are soft and yellow. Histopathology: - Stroma of spindle-shaped fibroblasts, arranged , at least focally, in a whorled, storiform pattern,among which variable number of small, multinucleated, osteclast-type giant cells are scattered. - Foam (xanthoma) cells, with small, dark nuclei are frequently, but not always found interpersed among the stromal cells individually, or in small clusters. - Scattered inflammatory cells, mainly lymphocytes, are present. - Small stromal hemorrhages and hemosiderin may be present. Prognosis: - Excellent. - Asymptomatic NOF usually do not need surgical excision. - Painful larger lesions or those that have an impending or established pathologic fracture are adequately treated by curretage.
BENIGN BONE TUMORS REFERENCES: WHO Pathology and Genetics of Tumors of Soft Tissue and Bone, Lyon: IARC Press, 2002 Dorfman H. D., Bone Tumors, New York: Mosby, 1998 Potter's, Pathology of the fetus, infant and child, Mosby/Elsevier 2007 Weiss W.S., Soft Tissue Tumors, Mosby/Elsevier 2008
MYOFIBROMA Definition: - Myofibroma and myofibromatosis are terms used to denote the solitary (myofibroma) and multicentric (myofibromatosis) occurence of benign neoplasms composed of contractile myoid cells arranged around thin-walled blood vessels. - Myofibroma(tosis) forms a morphological continuum with myopericytoma and so-called infantile. hemangiopericytoma. Epidemiology: - Myofibroma of bone affects very young children and many patients first develop lesions in utero. - Many cases are detected at birth or within first two years of life. - Male predominance. Sites of involvement: - Commonly involve the skull, jaw, ribs and pelvis. - Lesions of the appendicular skeleton are less frequent and usually involve the metaphyses of bones. Clinical findings: - May be asymptomatic, produce palpable mass or cause pain and even a pathologic fracture. Imaging: - Oval or elongate and lucent, with well circumscribed, sclerotic margins and may expand the bone. Gross: - Firm, tan-white and well delineated. Histopathology: - Central regions are usually densely cellular and composed of sheets of small round cells with a prominent vascular tree that has a hemangiopericytoma-like pattern. - Mitotic activity, necrosis, and dystrophic calcification are common findings. - This region merges peripherally with a component composed of intersecting fascicles of plump spindle cells that have blunt ended nuclei and conspicuous eosinophilic cytoplasm, which resemble smooth muscle cells. Immunohistochemistry: - Myofibroblastic and more primitive component are positive for vimentin and smooth muscle actin, while the myofibroblastic component is more strongly positive for pan-actin HHF-35. Prognosis: - Depends on whether there is one or multiple lesions and importantly, if there is visceral involvement. - The prognosis of bone lesions is excellent, and simple excision is usually curative. - Patients with multiple visceral lesions, especially those with involvement of the gastrointestinal tract may have a fatal outcome from severe hemorrhage.
DESMOPLASTIC FIBROMA Definition: - Rare, locally aggresive, solitary tumor microscopically composed of well differentiated myofibroblasts with abundand collagen production. Epidemiology: - Rare, 0.1% of all primary bone tumors. - It tends to occur in adolescent and young adults with near equal gender distribution. Sites of involvement: - May involve any bone but is most frequent in mandible. Clinical findings: - Pain and swelling of the affected area are the most common symptoms. - Pathologic fracture or deformity of the affected bone can occasionally be presenting symptom. Imaging: - Usually well defined, radiolucent lesion that may expand host lesion. - Interlesional trabeculation is frequent. - Larger lesion often show destruction of overlying cortex with extension into soft tissue. - Features of more aggressive growth pattern with irregular, ill-defined margins and pathological fracture may be present. - Honeycombed or moth-eaten patterns have been described. - Erosive, destructive pattern may mimic other, more aggressive lesions. - DF has low signal intensity in both T1 and T2 weighted MRI images. Histopathology: - Composed of spindle cells (fibroblasts/myofibroblasts) within an abundant, dense matrix of collagen. - Degree of cellularity is variable but cellular atypia and pleomorphism are minimal or absent. - Mitoses are rare. - Exhibits an infiltrative destructive growth pattern with permeation of bone marrow spaces and haversian canals. - Borders of the tumor, especially in soft tissue, are irregular with fingerlike projections infiltrating adipose tissue and skeletal muscle. Genetics: - Trisomies 8 and 20 detected. Prognosis: - DF exhibits locally aggressive behavior without capacity to metastasize. - Recurrence following curretage and resection are 72% and 17% respectively. - Local relapse has been reported as late as eight years following primary surgery.
CHEST WALL HAMARTOMA/CHONDROMATOUS HAMARTOMA OF THE CHEST WALL Definition: - Known as vascular-cartilaginous hamartoma, vascular hamartoma of infancy, mesenchymal hamartoma of chest wall, and chondromatous hamartoma of the chest wall, is a rare mesenchymal tumor that usually develops during fetal life or the first year of infancy. Epidemiology: - Fetal life or the first year of life. - Males are affected slightly more than females. Sites of involvement: - Arises from one or multiple ribs. Clinical findings: - May be asymptomatic or cause chest wall deformities or respiratory distress. Imaging: - Usually manifest as a large expansile mass that has well-defined sclerotic margins. - Tumor erodes the cortex and extends into extrapleural soft tissues, but is delineated by subperiosteal reactive bone. - Intralesional radio densities are often present and may consist of calcified cartilage that manifest as pop-corn like speckled foci and mineralized bone that may produce irregular trabeculations through the mass. - Hemorrhagic cystic cavities with flui-fluid levels (secondary aneurysmal bone cyst like regions) are common, and are seen by CT and T2-weighted MRI. Gross: - Frequently large and range in size from 5-16 cm in diameter. - Well circumscribed and consist of an admixture of firm, gray-white, glistening, focally gritty, solid areas, and numerous blood-filled cystic spaces. Histopathology: - Composed of different tissue components including nodules of hyaline cartilage surrounded by proliferating fibrovascular tissue, newly deposited bone and variably sized cysts. - Cystic spaces, which may dominate the mass, are filled with blood and the walls are composed of fibrous tissue, reactive bone and scattered osteoclast type giant cells. - Hyaline cartilage is moderately to densely cellular with chondrocytes frequently organized in a pattern that resembles growth plate. - At the periphery the matrix frequently undergoes enchondral ossification. Prognosis: - Excellent as recurrence is rare, and likely results from incomplete resection. - Main postsurgical complication has been scoliosis
OSTEOCHONDROMA (EXOSTOSIS) Definition: - Cartilage capped bony projection arising on the external surface of bone containing a marrow cavity that is continuous with that of the underlying bone. Epidemiology: - Most common bone tumor. - Osteochondroma may be solitary or multiple, the latter occuring in the setting of hereditary multiple exostoses. - Solitary lesions account for 80% of cases, and most affected patients are diagnosed in their second decade of life - Male preponderance with a male to female ratio 1.5-2:1. - Hereditary multiple exostoses (HME) is an autosomal dominant genetic disorder , and has prevalence of 1 per 50 000 in the general population making it one of the more common inherited skeletal disease. - Patients with HME come to medical attention at the younger age , usually during first decade, because they cause severe skeletal deformities and are frequently polyostic. Sites of involvement: - Generally arise in bones performed by cartilage. - Most common site of involvement is the metaphyseal region of distal femur, uppr humerus, upper tibia and fibula. Clinical findings: - Many, if not most lesions, are asymptomatic and found incidentally. In symptomatic cases, the symptoms are often related to the size and location of the lesion. - Most common presentation is that of a hard of long- standing duration. Imaging: - Bulbous lesions on X rays, and they a narrow or broad (sessile) osseous radiosense stalk, which is attached to the underlying bone. - The characteristic feature is a projection of the cortex in continuity with the underlying bone. - Excessive cartilage type flocullent calcification should raise the suspicion of malignant transformation. - CT scan or MRI images typically show continuity of the marrow space into the lesion. A thick cartilagenous cap rises suspicion of malignant transformation. Gross: - May be sessile or pedunculated. - The cortex and medullary cavity extends into the lesion. - The cartilage cap is usually thin. - A thick an irregular cap (greater than 2 cm) may be indicative of malignant transformation. Histopathology: - Lesion has three layers - perichondrium (fibrous layer covering cartilage), cartilage and bone. - Outer layer is a fibrous perichondrium that is continuous with the periosteum of the underlying bone. - Below this is a cartilage cap that is usually less than 2 cm thick (and decreases with age). - Within the cartilage cap the superficial chondrocytes are clustered, whereas the ones close to bone resemble growth plate. - Loss of the architecture of cartilage, wide fibrous bands, myxoid change, increased chondrocyte cellularity, mitotic. activity, significant chondrocyte atypia and necrosis are all features that may indicate secondary malignant transformation. Genetics: - Abberations involving 8q22-24.1, EXT1 gene. Prognosis: - Excision is usually curative. - Recurrence is seen with incomplete removal.
ENCHONDROMA AND ENCHONDROMATOSIS Definition: - Benign hyaline cartilage neoplasm of medullary bone. - Enchondromatosis, is defined as two or more enchondromas, and occurs in two clinical settings: 90% are associated with Ollier disease (two or more enchondromas) 10% are seen in Maffuci syndrome (enchondroma + hemangiomas) Epidemiology: - Relatively common, accounting for 10-25% of all benign bone tumors. - Age distribution is wide, ranging from 5-80 years. - Majority of patients present within the second through fourth decades of life. - Solitary enchondromas are rare in young children, whereas multiple enchondromas are encountered more frequently. - Sexes are equally affected. Sites of involvement: - Usually metaphyseal-diaphyseal in location and frequently affect the short tubular bones of the hands. - Followed by bones of the feet and the long tubular bones, especially proximal humerus and proximal and distal femur. Clinical findings: - In the small bones of the hands and feet typically present as palpable swellings, with or without pain. - Because they often expand these small bones and attenuate the cortex, they frequently present with pathological fractures. - Long bone tumors are more often asymptomatic, and are detected incidentally in radiographs or bone scans taken for other reasons. Imaging: - Well marginated tumors that vary from radiolucent to heavily mineralized. - Mineralization pattern is characteristic, consisting of punctatae, flocullent, or ring and arc pattern. - Long bone tumors are usually centrally located within metaphysis. - Diaphyseal long bone tumors are less common, and epiphyseal tumors are rare. - Enchondromas in the small tubular bones can be centrally or eccentrically located, and larger tumors may completely replace medullary cavity. - More extensive endosteal erosion is considered suspicious for low grade chondrosarcoma. - Cortical destruction and soft tissue invasion should never be seen in enchondromas and would be most consistent with chondrosarcoma. Gross: - Most enchondromas measure less than 3cm and tumor larger than 5 cm are uncommon. - They frequently have multinodular architectures, comprised by nodules of cartilage separated by bone marrow. - Multinodular pattern appears more common in long bones compared to confluent growth pattern in small tubular bones. Histopathology: - Nodules of hyaline cartilage that are well demarcated by the surrounding bone and frequently undrego enchondral ossification. - Cartilage shows hypo to moderate cellularity and contains chondrocytes of variable size. - Condrocyte nuclei tend to be small, round and hyperchromatic. - Scattered binucleated cells may be found. - Irregular purple granules within the matrix represent calcifications. - Chondromas of Ollier disease are histologically similar to those of sporadic solitary tumors; however, they frequently demonstrate a greater degree of cellularity, cytologic atypia, and may contain myxoid stroma, which may be confused with diagnosis of chondrosarcoma. Genetics: - Structural abnormalities involving chromosomes 6 and12 have been detected. Prognosis: - Solitary enchondromas successfully treated by intralesional curretage in most cases, and local recurrences are uncommon. - Clinical behavior of Ollier disease is unpredictable and there is no specialized treatment. - Most dangerous complication is malignant transformation of an enchondroma in Ollier disease. This occurs in 25-30% of affected patients. - Patients with Ollier disease must have lifetime monitoring of their tumors.
CHONDROBLASTOMA Definition: - Benign, cartilage producing neoplasm usually arising in the epiphyses of skeletally immature patients. Epidemiology: - Accounts for less than 1% of primary bone tumors. - Most patients are between 10 and 25 years of age at diagnosis and there is a male predominance. - Patients with skull and temporal bone involvement tend to present at an older age (40-50 years). Sites of involvement: - Usually arises in the epiphyses of the distal and proximal femur, followed by the proximal tibia and proximal humerus. - Patients with tumors arising in the flat bones, vertebrae and short tubular bones tend to be older and skeletally mature, although rare cases have been reported in children. Clinical findings: - Majority of patients complain of localized pain, often mild, but sometimes of many years duration. - Soft tissue swelling, joint stiffness and limitation, and limp are reported less commonly. - Minority of patients may develop joint effusion, especially around the knee. Imaging: - Typically lytic, centrally or eccentrically placed, relatively small lesions (3 to 6 cm), occupying less than one half of the epiphysis. - Sharpely demarcated, with or without a thin sclerotic border. - The presence of sclerotic rim, along with the younger age of the patient, helps to differentiate chondroblastoma from giant cell tumor of bone, which generally lacks sclerotic border and occurs in patients less than 20 years. - Often helpful, matrix calcifications are only visisble in about 1/3 of patients. Gross: - Gritty and grayish white with areas of hemorrhage. Histopathology: - Denselly cellular composed of an admixture of mononuclear chondroblasts and multinucleated osteoclast- type giant cells. - Chondroblasts grow in sheets, have eosinophilic cytoplasm, well defined cell borders, and eccentrically placed reniform or coffe-bean shaped nuclei. - Matrix generally consist of poorly formed matrix cartilage, which mineralization may form 'chicken-wire' pattern around single cells. - Mitotic activity and necrosis are commonplace. - Osteoclast-type giant cells are scattered throughout the tumor but are most numerous in areas of matrix production and hemorrhage. Immunohistochemistry: - Chondroblasts express S-100 and vimentin but may also stain for keratin and epithelial membrane antigen. Genetics: - Structural anomalies involving chromosomes 5 and 8. Prognosis: - 80-90% of chondroblastomas are successfully trated by simple curretage with bone grafting. - Local recurrence rates range between 14-18% and occur usually within two years. - Rare development of pulmonary metastases in histologically benign chondroblastoma is well documented, however this metastases are clinically non-progressive and can often be satisfactorily treated by surgical resection and/or simple observation.
LANGERHANS CELL HISTIOCYTOSIS (EOSINOPHILIC GRANULOMA) OF BONE Definition: - Previously known as histiocytosis X, is an intraosseous mass of proliferating Langerhans cells. - Langerhans cells are dendritic cells that normally populate the skin, mucosal surfaces, lymph nodes and other tissues where they function as specialized antigen presenting cells. - In Lngerhans cell histiocytosis, the proliferating cells are monoclonal, supporting the theory that the disease is neoplastic. Epidemiology: - LCH is relatively rare disorder, accounting for less than 1% of all osseous lesions. - Age distribution is ranging from the first month to 8th decade of life with 80-85% of cases seen in patients under the age of 30, and 60% under the age of 10. - Males are affected twice as often as females. Sites of involvement: - Any bone may be involved, although there is predilection for LCH to involve the bones of the skull, notably the calvarium. - Other frequently involved sites include the femur, the bones of the pelvis, and the mandible. Clinical findings: - Pain and swelling of the affected area occur most commonly. - In cases of temporal bone involvement , the presenting features can show significant clinical overlap with otitis media and mastoiditis. - Mandibular involvement , loosening or loss of teeth can be encontered. - Vertebral body involvement may result in compression fracture and possible neurological impairment. LCH is associated with variety of clinical syndromes. - Single or multiple lesion restricted to skeleton have been termed eosinophilic granuloma. - Multifocal bone disease associated with exophthalmos and diabetes insipidus is known as Hand-Shuller-Christian disease, and Letterer-Siwe disease is an aggressive disseminated form of the disorder that occurs in infants. - Letterer-Siwe disease usually affects very young childrens less than 2 y/o, whereas, Hand-Schuller-Christian disease and eosinophilic granuloma are seen in older children and young adults. Imaging: - LCH lesions are well defined and lytic on radiographs, however, in a minority of cases may have ill-defined and permeative margins. - Cortical involvement may elicit a periosteal reaction. - Complete resolution of radiographic abnormalities may follow treatment or occasionally occurs spontaneously. Gross: - Involved tissue is soft and is red in color. Histopathology: - Proliferating Langerhans cells are ovoid or round histiocyte-like cells that are arranged in aggregates, sheets, or individually within a loose fibrous stroma. - The cells have eosinophilic cytoplasm and contain central ovoid 'coffe bean' shaped nuclei with typical nuclear grooves. - Chromatin is either diffusely dispersed or condensed along the nuclear membranes. - Langerhans cells are frequently admixed with inflammatory cells including large numbers of eosinophils, as well as lymphocytes, neutrophils and plasma cells. - Necrosis may be found in minority cases and if is prominent, is usually complication of a pathologic fracture. - Mitotic figures may be seen; however atypical forms are absent. Immunohistochemistry: - Langerhans cells are positive for CD1a, S100 and negative for CD68 and CD45. Electron Microscopy: - Intracytoplasmic 'tennis racket' shaped inclusions known as Birbeck granules. Prognosis: - Treatment and prognosis of LCH depends on the site and size of the lesion, the age of the patient, and the presence or absence of multifocal disease. - Monostotic disease is usually managed by curettage, however tumors located in areas difficult to excise may be treated with low dose radiation therapy. - Single or multiagent therapay may be administered in the setting of disseminated disease.
ROSAI-DORFMAN DISEASE Definition: - Sinus histiocytosis with massive lymphadenopathy (Rosai- Dorfman disease) is a rare, proliferative, histiocytic disease characterized by the enlargement of lymph node sinuses caused by an aggregation of histiocytic cells that exhibit marked lymphophagocytosis (numerous phagocytized lymphocytes are present in cytoplasm). - Primary or secondary involvement of extranodal sites, including the skeleton, is frequent. Epidemiology: - Majority of patients are teenagers and young adults. - Mean age 20 years. - No gender predilection. - Soliatary RDD in bones was described in young childrens. Clinical findings: - Fever and massive cervical lymphadenopathy are the most frequent symptoms at presentation. - Other symptoms include weight loss, malaise and night sweats. - Quite often the disease fully manifests after a short period of a nonspecific fever and pharyngitis. Imaging: - Skeletal involvement manifests by the presence of solitary or multifocal defects with poorly or well-demarcated borders. - RDD lesions are intramedullary and are associated with cortical erosion, complete cortical disruption, elevation of the periosteum, or a combination of these features. - Radiographic manifestations and clinical symptoms suggest an inflammatory disorder, such as osteomyelitis. Histopathology: - In typical cases, the sinuses of lymph nodes are filled with histiocytic cells. - These cells have prominent eosinophilic cytoplasm, indistinct borders, and round or oval nuclei with a very fine chromatin pattern and a single small nucleolus. - Nuclear grooves are not present, and some of these cells may have several nucleoli. - Occasional cells with multilobulated nuclei may be present. - Mitotic figures are rare, atypical mitoses are not present. - The most striking and diagnostically important feature of histiocytic cells is prominent emperipolesis or lymphophagocytosis (i.e. the presence of well-preserved lymphocytes within their cytoplasm). - In addition to lymphocytes, a smaller number of phagocytized plasma cells, neutrophils, and red cells is also present. - Extranodal disease has all these features except that histiocytic cells, instead of growing in sinuses, form irregular geographic areas separated by other inflammatory cells. - Involvement of skeletal system has the same features. Immunohistochemistry: - Histiocytic cells in RDD are S 100 positive and CD1a negative. Prognosis: - Rosai-Dorfman disease is considered a histologically benign, proliferative, histiocytic disorder with a variable, but occasionally fatal, outcome. - The majority of patients have indolent regressive or clinically stable disease after several years of follo-up. - Fatal outcome of the disease is associated with the severe involvement of extranodal sites (lungs and kidney).
HEMANGIOMA OF BONE Definition: - Hemangioma is benign solitary tumor composed of newly formed vessels of capillary or cavernous type. Epidemiology: - Wide age distribution, ranging from the first to eight decades of life, with nearly 70% of the cases diagnosed in patients between 30 and 60 years. - Occasionally hemangiomas become clinically evident during the first decade of life. There is no sex predilection. - They are rare in newborns and infants and reported cases have arisen in the skull bones. - The tumors are usually solitary, but multifocal neoplasms have been described most frequently in the vertebral columns. Sites of involvement: - Hemangiomas frequently occur in craniofacial bones , predominantly in calvarium (50%), followed by the spine (20%). Clinical findings: - Relatively common asymptomatic. Imaging: - Hemangiomas present as lucent, well demarcated defects. - In flat bones, they markedly expand the bonecontour and produce rarefaction with radially oriented striations. - Vascular nature of the lesion often is suggested by its bubbly or honeycomb trabeculated appearance. - Overlying cortex is expanded and thinned, but complete cortical disruption and invasion into soft tissue are not present. - Chracteristic sunburst appearance of hemangioma is seen in skull lesion (not confuse with that seen in osteosarcoma of long bones). - Smaller lesions may present as intracortical rarefaction with or without a honeycombed appearance and adjacent sclerosis. - MRI of hemangiomas generally reveals a low signal on T1- weighted images and a high signal on T2 weighted images (fluid content of tumor vessels). Gross: - Brown-red or dark red, well demarcated, medullary lesion. - It may have a honeycomb appearance with sclerotic bone trabeculae interspersed among hemorrhagic cavities. Histopathology: - Hemangiomas are composed of conglomerate of thin-walled blood vessels. - Vessels can have dilated open channels (cavernous hemangioma) or less frequently may be composed of capillary-sized vessels (capillary hemangioma). - Majority of bone hemangiomas are of cavernous or mixed types. - Vascular channels are lined by a single layer of flat endothelial cells. - Intercellular tissue is composed of loose connective tissue that may show myxoid change. - Bone may be completely resorbed in affected area. - Vascular channels of hemangioma are complete, separate and do not show anastomosing pattern. Prognosis: - Asymptomatic small hemangiomas require no treatment; some may undergo spontaneous regression. - Symptomatic lesions or those that are large and may cause pathologic fracture or vertebral collapse require treatment. - Curretage and bone grafting usually is sufficient.
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OSTEOID OSTEOMA Definition: - Benign bone-forming tumor. - Similar to osteoblastoma but smaler size (1.5 - 2.0 cm). Epidemiology: - Children and adolescent. Sites of involvement: - Most common in long bones, femur/tibia (cortex of metaphysis) - May be found in any bone. Clinical findings: - Intense localized pain particularly at night. - Pain relieved by aspirin , NSAIDs or surgery. Imaging: - Small, round lucency. - Variable mineralization surrounded by extensive. sclerosis. Macroscopy: - Small cortically based, - Red, gritty round lesion Histopathology: - Limited growth pattern (1.5- 2.0 cm). - Bony trabecules lined by plump osteoblast. - Vascularized connective tissue: surrounded by sclerotic bone. - Benign giant cells may be present. Genetics: Prognosis: - Excellent, recurrences rare after surgical excision. Differential Diagnosis: - Osteoblastoma - Osteomyelitis
GIANT CELL TUMOR Definition: - Benign, locally aggressive neoplasm. - Composed of sheets of neoplastic ovoid mononuclear cells interspersed with uniformly distributed large, osteoclastlike giant cells. Epidemiology: - Giant cell tumour represents around 4-5% of all primary bone tumours. - Peak incidence is between the ages of 20 and 45. - 10-15% of cases occur in the second decade. - Not commonly seen in adolescents, although cases were described. - There is slight female predominance described. Sites of involvement: - Giant cell tumours typically affect the ends of long bones, especially the distal femur, proximal tibia, distal radius and proximal humerus. - About 5% affect flat bones, especially those of the pelvis. - Multicentric giant cell tumors are very rare and tend to involve the small bones of the distal extremities. Clinical findings: - Patients typically present with pain, swelling and often limitation of joint movement - Pathological fracture is seen in 5-10% of patients. Imaging: - X-rays of lesions in long bones usually show an expanding and eccentric area of lysis. - Lesion normally involves the epiphysis and adjacent metaphysis. - Extension up to the subchondral plate, sometimes with joint involvement may be present. - Rarely, the tumour is confined to the metaphysis,usually in adolescents where the tumour lies in relation to an open growth plate,but occasionally also in older adults. - Diaphyseal lesions are exceptional. - CT scanning gives a more accurate assessment of cortical thinning and penetration than plain radiographs. Gross: - Tissue is usually soft and reddish brown, but there may be yellowish areas corresponding to xanthomatous change. - Firmer whiter areas represent fibrosis. - Bloodfilled cystic spaces are sometimes seen and may mimick aneurismal bone cyst. Histopathology: - Tumor is composed of round to oval polygonal or elongated mononuclear cells evenly mixed with numerous osteoclastlike giant cells which may be very large and contain 50 to 100 nuclei. - The nuclei of the stromal cells are very similar to those of the osteoclasts, having an open chromatin pattern and one or two small nucleoli. - The cytoplasm is ill-defined, and there is little intercellular collagen. - Mitotic figures are invariably present, but no atypical mitoses present. - It is now generally accepted that the characteristic large osteoclastic giant cells are not neoplastic. - The mononuclear cells, which represent the neoplastic component, are thought to arise from primitive mesenchymal stromal cells. - Areas of fibrosis may be present. - Secondary aneurysmal bone cyst change may occurs in 10% of cases. - 1/3 of cases, show presence of intravascular plugs, particularly at the periphery of the tumour. - Areas of necrosis are common, especially in large lesions. - These may be accompanied by focal nuclear atypia which may suggest malignancy Genetics: - Telomeric association is the most frequent chromosomal aberration. - The telomeres most commonly affected are 11p, 13p, 14p, 15p, 19q, 20q and 21p. Prognosis: - Giant cell tumour is capable of locally aggressive behaviour and occasionally of distant metastasis. - Histology does not predict the extent of local aggression. - Local recurrence occurs in approximately 25% of patients, and is usually seen within 2 years. - Pulmonary metastases may be seen in 2% of patients with giant cell tumours, on average 3-4 years after primary diagnosis.
OSTEOMYELITIS Definition: Inflammation of bone and marrow also known as infection of bone May manifest as a primary solitary focus of disease or as a complication of other systemic disease. May be caused by different bacterial organisms Types of osteomyelitis: Pyogenic Osteomyelitis Hematogenous osteomyelitis commonly occurs in children. Staphylococcus aureus is the most common organism responsible for pyogenic osteomyelitis H. inflenzae & group B streptococci are frequent pathogens in neonatal infection. Gram negative organisms are isolated from patients with genitourinary infection or who are IV drug abusers Almost always caused by bacteria. Organisms reach to the bone by: 1 hematogenous spread 2 extension from a contiguous site 3 direct implantation The latter (3) occurs as a complication of a compound fracture or of surgery. Symptoms: High fever, localized pain and swelling Labs: high white cell count, high ESR. Most frequent site in children: distal femur, proximal tibia proximal humers and distal radius all of which are areas of rapid growth Site of infection in the bone is influenced by high vascular supply In neonate, the metaphyseal vessels penetrate the growth plate resulting in infection of metaphysis, epiphysis or both In children metaphyseal localization. In adult subchondral region or vertebral localization Morphology: Rupture of the periosteum leads to soft tissue abscess and draining sinus In infants epiphyseal infection spread through the articular surface causing destruction of the cartilage leading to joint infection also known as septic or suppurative arthritis. In vertebrae, the infection destrys the hyaline cartilage end plate and intervertebral disk and spreads to the adjacent vertebrae Depends on stage (acute, subacute or chronic). Bacteria localized in bone induce acute inflammation and cell death. Bone necrosis in 48 hours and spread of infection to the periosteum via haversian system leading to periosteal elevation and subperiosteal abscess formation. This process impairs the blood supply causing segmental bone necrosis, the dead piece of bone is known as Sequestrum. Radiology: Lytic focus of bone destruction with peripheral zone of sclerosis and reactive periosteum. MRI: increased signal intensity in the medullary space. D.D.: small round blue cell tumor Chronic osteomyelitis: One week after the infection, host response evolves with infiltration by chronic inflammatory cells and release of cytokines which in turn stimulates osteoclastic bone resorption, ingrowth of fibrous tissue and reactive new bone formation. Reactive bone in the form of a living tissue around the segment of necrotic bone (sequestrum) is known as involucrum. Variants of osteomyelitis: Brodie abscess – small intraosseous abscess that frequently involves the cortex and is walled of by reactive bone. It may mimick tumor. Sclerosing osteomyelitis of Garre affects the jaw bone with extensive new bone formation. Chronic Recurrent Multifocal Osteomyelitis Clinical course: Blood culture may be positive Antibiotics and surgical drainage are the usual treatment. In 5% to 25% cases, the infection persists as chronic osteomyelitis. Acute flare ups can occur after years of dormancy. Rare complications: fracture, sepsis, scc in the sinus and bone sarcoma.
Angiomatoid Fibrous Histiocytoma of Bone Definition: