CONVENTIONAL OSTEOSARCOMA Definition: Primary intramedullary high grade malignant sarcoma in which neoplastic cells produce osteoid. Epidemiology: Most common primary non-hematopoietic malignancy of bone. Its incidence in USA is 4-5 per milion individuals with 1000-1500 new cases diagnosed annually which accounts for approximatelly 20% of all primary malignant cell tumors. It most frequently occurs in second decade of life with 60% of tumors occuring in patients younger than 25 years. Although 30% occuring in patients over 40 years of age, the predisposing condition should always be considered in older patients (e.g. Paget's disease, of bone, post radiation sarcoma). Male to female ratio 3:2. Osteosarcoma in children 5 years and younger is very uncommon, and they account for less than 2% of osteosarcomas in the pediatric population. Sites of involvement: Conventional osteosarcoma shows a profound propensity for involvement of the long bones of the appendicular skeleton; in particular , the distal femur, proximal tibia, and proximal humerus. Within the long bones the tumor is mostly centered in metaphysis (90%) followed by diaphysis (9%), and rarely in epiphysis. Although the long bones remain the most frequent site of involvement, the non-long bone (i.e, jaws, pelvis, spine, and skull) involvement tends to increase with age. Clinical features: Classic presentation of conventional osteosarcoma typically is progressively enlarging, painfull mass. Deep seated and boring in nature, the pain is frequently noted months prior to diagnosis, and usually increases in intensity over time, eventually becoming unbearable. Skin overlying the tumor may be warm, eyrthematous, edematous, with prominent engorged veins. Large tumors may restrict range of motion,decrease musculoskeletal function,produce joint effusion and, in advances cases,result in weight loss and cachexia. A sudden fracture through destructive mass may be found. Imaging: Osteosarcoma has extremely variable radiographic appearances; Conventional tumors present as a large, destructive, poorly defined, mixed lytic and blastic masses accompanied by cortical destruction and tumor extension into soft tissue. Tumor/periosteal interaction may lead to variety of manifestations secondary to periosteal elevation (e.g. Codman triangle) and periosteal reactive bone formation. Occasionally the tumor may demonstrate perpendicular or radiating striations called "sunburst". CT and MRI may be helpfull in delineating the extent of the tumor preoperatively. Gross: Osteosarcoma is often a large (over 5 cm), metaphyseally centered, fleshy or hard tumor which may contain cartilage. It frequently transgresses the cortex and is associated with a soft tissue mass. Histopathology: Presents as highly anaplastic, pleomorphic tumor in which the tumor cells may be: epithelioid, plasmacytoid, fusiform, ovoid, small round cells, clear cells, mono- or multinucleated giant cells, or spindle cells producing osteoid. Conventional osteosarcoma can also produce varying amounts of cartilage and/or fibrous tissue. Many investigators further subdivide conventional osteosarcoma in terms of predominant matrix. This divides conventional sarcoma into three subtypes: osteoblastic (50%), chondroblastic (25%), and fibroblastic (25%) osteosarcoma. Osteoblastic osteosarcoma: Bone and/or osteoid are the predominant matrix. The extremes of matrix production are thin arborising osteoid to dense, compact osteoid and bone (sclerotic). Chondroblastic osteosarcoma: Chondroid matrix is predominant. It tends to be high grade hyaline cartilage, which is intimately associated, and randomly mixed, with non-chondroid elements. Fibroblastic osteosarcoma: A high grade spindle-cell malignancy with sometimes minimal amount of osseous matrix with or without cartilage. In general, the overall histological appearance is similar to fibrosarcoma or pleomorphic undifferentiated sarcoma (malignant fibrous histiocytoma). Genetics: Loss of heterozygosity of chromosome arm 3q, 13q, 17p, and 18q most frequent. Amplification at 1q21-23 and 17p are frequent findings in conventional osteosarcoma. Prognosis: Untreated, conventional osteosarcoma is fatal. Aggresive local growth and rapid hematogenous systemic dissemination are bad prognostic features. Although metastases may affect many sites, pulmonary metastases are the most frequent site of clinically significant systemic disease. In children the treatment of conventional osteosarcoma is tailored to the location, size and stage of the tumor. Eradication of the primary tumor and the elimination of any matastases is the goal of therapy. Limb salvage resection is the convention for appendicular tumors, and surgical excision in combination with radiation is employed for tumors that are not resectable entirely with negative margins. Adjuvant chemotherapy is usually employed in the preoperative setting and continued after surgical resection. Survival is directly related to response to pre-operative therapy. In those patients whose tumors have >90% tumor necrosis, long-term survival is generally 80-90%. In patients with < 90% response to therapy the survival is poor, usually <15%.
MALIGNANT BONE TUMORS BONE PRODUCING TUMORS SMALL BLUE CELL 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
TELANGIECTATIC OSTEOSARCOMA Definition: • Malignant bone forming tumor characterized by large spaces filled with blood with or without septa. Epidemiology: • Rare subtype, accounting for less than 4% of all cases of osteosarcoma. • It most frequently occurs in the second decade of life but was described in younger patients. • Male to female ratio 1.5:1. Sites of involvement: • Most tumors involve metaphyseal region of long tubular bones. • Distal femoral metaphysis is the single most common anatomic site, followed by the upper tibia and proximal humerus or proximal femur. Clinical findings: • Similar to conventional osteosarcoma. • Characteristic clinical finding of this tumor is pathological fracture (1/4 of the cases),because of massive bone destruction. Imaging: • Purely lytic, large bone destruction without distinct surrounding bony sclerosis. • Tumor commonly show extension into soft tissue. • Most lesions are located in metaphysis, and ususally extend into the epiphysis. • Tumor often expand the cortex of bone and distrupt the cortex. • Periosteal reaction including Codman's triangle and onion skin are frequent. • MRI, a T1-weghted image shows heterogenous low signal intensity, and T2-weighted image shows high signal intensity with several cystic foci and fluid-fluid level with an extraskeletal extension of the tumor, similar to aneurysmal bone cyst. Gross: • Tumors show dominant cystic architecture in the medullary space. • Cystic portion of the tumor is filled incompletely with blood clot which is described as "a bag of blood". • There is no sclerotic tumor bone formation. Histopathology: • Tumor contains blood-filled or empty spaces separated by thin septa simulating aneurysmal bone cyst. • A few of the tumors are more solid and have smaller cystic spaces. • Higher power view shows the cystic spaces lined by benign-looking giant cells without endothelial cells. • The septa are cellular, containg atypical mononuclear tumor cells. • Tumor cells are hyperchromatic and pleomorphic with high mitotic activity including atypical mitoses. • Amount of osteoid varies, but usually fine, and lace like osteoid is observed in minimal amount. • Cellular septae contain many benign looking multinucleated giant cells, which may lead to a mistaken diagnosis of benign or even malignant giant cell tumor. Genetics: • Mutations in TP53 and RAS genes. Prognosis: • Similar to conventional osteosarcoma. • Sensitive to chemotherapy.
SMALL CELL OSTEOSARCOMA Definition: • Osteosarcoma composed of small cells with variable degree of steoid production. Epidemiology: • Small cell osteosarcoma comprises 1.5% of osteosarcomas. • Patients range from 5 to 80 y/o, although most patients are in the second decade. • There is slight predilection for females. Sites of involvement: • Metaphysis of long bones. Rarely multiple sites are involved. Clinical findings: • Pain and swelling of involved site. Imaging: • Aggressive process with destruction of the cortex. • There is always a lytic component, usually admixed with radiodense areas. • Mineralized tissue is seen, either intramedullary and/or in soft tissue tumor extension. Histopathology: • Small cell osteosarcoma is composed of small cells associated with osteoid production. • Nuclear diameter of round cells can range in size from very small to medium; the smaller one are comparable to those of Ewing sarcoma or lymphoma. • The cells have scanty amounts of cytoplasm. Nuclei are round to oval and the chromatin may be fine to coarse. • Mitoses range from 3 to 5 /HPF. • In the less frequent spindle cell type, nuclei are short, oval to spindle, have a granular chromatin, inconspicuous nucleoli and scanty amounts of cytoplasm. • Lace-like osteoid is always present. • Biopsy from small cell osteosarcoma may be problematic, especially from the peripheral surface of the tumor, because may not always show osteoid and may resemble Ewing sarcoma. • In this cases cytogenetic study for t(11,22) is the best diagnostic tool, which is negative in small cell osteosarcoma. Immunohistochemistry: • Positive for CD99, vimentin, osteocalcin, osteonectin. Genetics: • Negative for t(11,22). Prognosis: • Poor.
LOW GRADE CENTRAL OSTEOSARCOMA Definition: • Low grade osteosarcoma that arises from the medullary cavity of bone. Epidemiology: • Accounts for less than 1% of primary bone tumors and only 1-2% of all osteosarcomas. • Males and females are equally affected. • The peak incidence is in 2nd-3rd decades of life. Sites of invovement: • Approximately 80% of low grade central osteosarcoma are located in the long bones with predilection for the distal femur and proximal tibia. • Flat bones are uncommonly affected. Clinical features: • Pain and swelling are usual features. • The duration of pain may be many months or even several years. Imaging: • Large metaphyseal or diaphyseal intramedullary tumors. • It is not uncommon to see extension into the end of the bone when the epiphyseal plate is closed. • Majority of tumors are poorly marginated, up to 1/3 may show intermediate or well defined margins suggestive of indolent or benign lesion. • Trabeculation and sclerosis are common findings that reflects indolent nature of this tumor. • Cortical destruction is the most convincing radigraphic feature to support malignant nature of the tumor. • The majority of low grade central osteosarcomas will show some degree of cortical destruction with or without soft tissue extension. Gross: • Cut surface of a low grade central osteosarcoma shows a grey-white tumor with a firm and gritty texture arising from within the medullary cavity. Histopathology: • Low grade osteosarcoma is composed of a hypo- to moderately cellular fibroblastic stroma with variable amounts of osteoid production. • The collagen producing spindle cells are arranged in interlacing bundles thet permeate surrounding pre-existing bony trabeculae and bone marrow similar to that of desmoplastic fibroma. • Tumor cell show some degree of cytological atypia. • Nuclear enlargement and hyperchromasia are evident. • Occasional mitotic figures are identified. • Variable patterns of bone production are seen. • Some tumors contain irregular anastomosing, branching, and curved trabeculae simulating the appearance of woven bone in fibrous dysplasia ( no atypia seen in spindle cells of fibrous dysplasia). • Small scattered foci of atypical cartilage are occasionally seen. • In addition, benign multinucleated giant cells have been reported in up to 36% of cases. Genetics: • Recurrent gains in minimal common regions at 12q13-14, 12p, and 6p21. Prognosis: • Low grade central osteosarcoma behaves in a much more indolent fashion conventional osteosarcoma. • High incidence of local recurrence after inadequate excision. • Recurrence may exhibit higher grade or differentiation with the potential for metastases.
PAROSTEAL OSTEOSARCOMA Definition: • Parosteal osteosarcoma is a low grade osteosarcoma which arises on the surface of bone. Epidemiology: • Although rare , parosteal osteosarcoma is the most common type osteosarcoma of the surface of bone. • It accounts for about 4% of osteosarcomas. • There is a slight female predominnce. • Most of the patients are young adults, about 1/3 occurs in 3rd decade of life. Sites of involvement: • 70% of cases involve the surface of the distal posterior femur. • The proximal tibia and proximal humerus are also common. Clinical findings: • Painles swelling; inability to flex the knee may be the initial symptom. • Some patients may complain of a painful swelling. Imaging: • Heavily mineralized mass attached to the cortex with broad base. • Tumor has tendency to wrap around the involved bone. • CT and MRI are useful in evaluating the extent of medullary involvement. Gross: • Parosteal osteosarcoma presents as a hard lobulated mass attached to the undrelying cortex. • Nodules of cartilage may be present. • Occasionally, the cartilage will be incomplete cap-like, covering the surface and thus suggesting a diagnosis of osteochondroma. Histopathology: • Parosteal osteosarcoma consist of well formed bony trabeculae in spindle cell stroma. • The spindle cells show minimal atypia, mitoses can be found with difficulty, atypical forms are not present. • The bony trabeculae are arranged in a parallel manner and simulate normal bone. • The trabeculae may or may not show osteoblastic rimming. • About 50% of the tumors will show cartilagenous differentiation. This may be in the form of hypercellular nodules of cartilage within the tumor or as a cap on the surface. • When cartilage cap is present may be mildly hypercelllular, and the cells may show mild atypia and lack columnar arrangemet seen in osteochondroma. • Unlike fatty and hematopietic marrow, as seen in osteochondromas, there is spindle cell proliferattion between bony trabeculae. • About 15% will show high grade spindle cell sarcoma (dedifferentiation). Prognosis: • Excellent with 91% overall survival at 5 years.
PERIOSTEAL OSTEOSARCOMA Definition: • Periosteal osteosarcoma is intermediate grade chondroblastic osteosarcoma arising on the surface of the bone. Epidemiology: • Accounts for less than 2% of all the osteosarcomas. • Of the surface osteosarcomas, it is more common than surface high grade osteosarcoma, but about 1/3 as common as parosteal osteosarcoma. • The peak incidence is the 2nd and 3rd decades of life. • There is a slight male predominance. Sites of involvement: • Diaphysis or diaphyseal-metaphyseal area of long bones, with the tibia and femmur most commonly affected. Clinical features: • Painless mass or limb swelling is the most common initial finding with pain and tenderness later developing in the affected area. Imaging: • Arising on the surface of a bone, displays nonhomogenous, calcified spiculations that are disposed perpendicular to the cortex and give overall sunburst appearance. • The lesion decreases in density from the cortical base to the surface, where the tumor has a relatively well demarcated margin. • Commonly, the cortex appears thickened as a result of the production of ossified matrix. • A codman's triangle is commonly present. • CT and MRI important in the evaluation of tumor size, integrity of the cortex, and soft tissue extension. Gross: • Tumor arises from the bone surface and may involve part of the bone or the entire circumference. Histopathology: • Periosteal osteosarcoma has the appearance of a moderately differentiated chondroblastic osteosarcoma. • Ossified mass is generally found arising from the cortex, and is made up of relatively mature bone. • Cartilagenous component predominates, but elements of intermediate grade osteosarcoma are invariably present. • Cartilagenous component may show varying degrees of cytological atypia and matrix may be myxoid. • Periphery is most of the time not calcified and made of fascicles of spindle cells. Prognosis: • Better prognosis than conventional osteosarcoma, but still have tendency to recur and metastasize. • Medullary involvement of the bone may have poorer prognosis. • About 70% recurrence rate after excision. • Rate of metastasis has been reported to be about 15%.
HIGH GRADE SURFACE OSTEOSARCOMA Definition: • High grade bone forming malignancy which arises from the surface of the bone. Epidemiology: • Less than 1% of all osteosarcomas. • Peak incidence is in 2nd decade of life. • There is slight male predilection. Sites of involvement: • Femur is most commonly affected followed by frequency by the humerus and tibia. Clinical features: • Patients commonly present with the mass or pain in the area of the tumor. Imaging: • Surface mass, partially mineralised, extending to soft tissue. • The underlying cortex is commonly partially destroyed, and periosteal new bone is commonly present at the periphery of the tumor. • Cross sectional imaging may show minimal medullary involvement, but the tumor is most comonly relateively well circumscribed at its soft tissue margin. Gross: • Tumor is situated on the surface of the bone and commonly erodes the underlying cortical bone. Histopathology: • Show similar morphology to conventional osteosarcoma. • Regions of predominantly osteoblastic, chondroblastic or fibroblastic differentiation may predominate. • However, all tumors will show high grade cytological atypia and lace-like osteoid as seen in conventional osteosarcoma. Prognosis: • As in conventional osteosarcoma, prognostic feature is response to chemotherapy.
SECONDARY OSTEOSARCOMA Definition: • Bone forming sarcomas occuring in bones affected by preexisting abnormalities the most common being postradiation therapy chnges, Paget disease, and rarely various other disorders. POSTRADIATION OSTEOSARCOMA Epidemiology: • Consitute 3.4-5.5% of all osteosarcomas and 50-60% of radiation-induced sarcomas. • It is estimated thet the risk of developing osteosarcomain irradiated bone is 0.03-0.8%. • Children treated with high-dose radiotherapy and chemotherapy are at greatest risk. • The prevalence of post-radiation osteosarcomas is increasing as children survive treatment of their malignant disease. Sites of involvement: • Any irradited bone, but the most common locations are the pelvis and the shoulder region. Clinical findings: • H/O of previous radiation therapy and tumor developing in the path of radiation beam. • A symptom free latent period may be long (median of 11 years), and inversely related to the radiation dosage. • Radiation doses are usually greter than 20 Gy. • From experience I've seen few osteosarcomas in patients with h/o of synovial sarcoma radiation therapy in young children. Imaging: • Tumors are densly sclerotic or lytic lesions with a soft tissue mass. • Radiation osteitis is present in about 50% of cases (trabecular coarsening and lytic areas in cortex). Histopathology: • High grade osteosarcoma predominate (see conventional osteosarcma). Prognosis: • 5-year survival rate is of 68.2% for patients with extremity lesions, 27.3% for patients with axial lesions. PAGET OSTEOSARCOMA • Paget disease is estimated to be 0.7-0.955, and osteosarcomas represent 50-60% of Paget sarcomas. • In most series, Paget osteosarcoma is more common in man (M:F 2:1), with an overall median age of 64 years. • It is osteosarcoma of older patients, not found in pediatric population. OSTEOSARCOMA ASSOCIATED WITH FIBROUS DYSPLASIA • Most commonly associated with Albright syndrome (also called McCune-Allbright syndrome and polyostotic fibrous dysplasia = bone polyostotic fibrous dysplasia + skin pigmentation and precosious puberty (other endocrine abnormalities)
EWING SARCOMA/ PRIMITIVE NEUROECTODERMAL TUMOR (PNET) Definition: • Ewing sarcoma/PNET are defined as small round cell sarcoma (belong to group of pediatric small blue cell tumors) that show varying degrees of neuroectodermal differentiation. • Ewing sarcoma is used term for those tumors which lack neuroectodermal differentiation, and PNET has been described for tumors with neuroectodermal differentiation. Epidemiology: • Ewing sarcoma accounts for 6-8% of primary bone tumors. • It is the second most common sarcoma in bone in children. • Male:female ratio 1.4: 1. • Nearly 80% are younger than 20 y/o, and the peak incidence is during the second decade of life. Sites of involvement: • Arise in the diaphysis or metaphyseal-diaphyseal portion of long bones. • The pelvis and ribs are also common locations. Clinical features: • Pain and a mass in the involved area are the most common clinical symptoms. • Fever, anemia, leukocytosis and increased sedimentation rate are often seen. Imaging: • Ill defined osteolytic lesion involving diaphysis of long bone or flat bone is the most common feature. • Permeative or motheaten bone destruction often associated with "onion-skin" like multilayered periosteal reaction is characteristic. • The cortex overlying the ti=umor is irregulary thinned and thickened. • A large ill-defined soft tissue mass is frequently seen. • Expansile bone destruction with soap-bubble appearance might be seen. Gross: • The tumor in bone and soft tissue is tan-grey and often necrotic and hemorrhagic. Histopathology: • Most cases are composed of of uniform small round cells with round nuclei containing fine chromatin, scanty clear or eosinophilic cytoplasm, and indistinct cytoplasmic membranes, whereas in others, the tumor cells are larger, have prominent nucleoli, and irregular contours. • The cytoplasm of the tumors frequently contains PAS positive glycogen ( diastase sensitive). • In some cases Homer-Wright rosettes are present. • Necrosis is common with viable cells frequently perivascular in distribution. Immunophemotype: • Positive: Fli-1, CD99, vimentin, neuron specific enolase (NSE), PAS+ diastase sensitive. • Negative: S100, CD45, muscular and vascular markers Genetics: • t(11,22) (q24;q12) - 85% • t(21;22) (q22;q12) - 10-15% • t(7;22), t(17;22), t(2;22) - 1% Prognosis: • Has improved with adjuvant therapy. • Important prognostic features include the stage, anatomic location and the size of the tumor. • Tumors that are metastatic at the time of the diagnosis, arise in the pelvis, and when they are large tend to do poorly.
LYMPHOMA OF BONE Definition: • Malignant lymphoma is a neoplasm composed of malignant lymphoid cells, producing a intra-medullary tumor mass. Epidemiology: • Malignant lymphoma involving bone is not common, accounting for approximately 7% of all bone malignancies. • Lymphomas involving bone account for about 5% of extranodal lymphoma. • Patients may be of any age group but there is tendency to involve adults, especially older patients, although there were cases of young childrens causing difficult diagnostic differentiation from Ewing sarcoma. Sites of involvement: • Affects portion of bone with persistent bone marrow. • Femur is the most commonly involved single site. • It is extremely unusual to see malignant lymphoma involving the small bones of the hand and feet. • Clinical features: • Majority of patients present with bone pain. • Some patients may present with palpable mass. • Patients with primary lymphoma of bone rarely present with systemic symptoms like fever or night sweats. • Lymphoma involving bone may be separated into four groups: 1) an single skeletal site, with or without regional lymph node involvement; 2) multiple bones are involved, but there is no visceral or lymph node involvement; 3) patients present with a bone tumor but work up shows involvement of other visceral sites or multiple lymph node sites; 4)patient has a known lymphoma and the bone biopsy is done to r/o involvement of bone; Groups 1 and 2 are considered primary lymphoma of bone. Imaging: • In the long bones, diaphysis tends to be more involved. • Tumor tends to involve a large portion of bone; it is not unusual to see destruction of more than half of the bone. • The process is poorly demarcated with a wide area of transition from normal bone. • There may be variable sclerosis; rarely, the tumor is very sclerotic or entirely lytic. • Most of the time there is mixture of sclerotic and lytic areas. • Cortex is frequently destroyed and there is large soft tissue mass. • A purely sclerotic lesion may be mistaken for Paget's disease. • If the cortex is not involved, the marrow destruction may not be obvious on plain roentgenograms. • Radionuclide bone scan is almost always positive. Gross: • Llarge portion of bone is involved, with cortical destruction. • The lesion has the soft fish-flesh appearance of lymphoma. Histopathology: • Majority of lymphomas invoving bones show diffuse growth pattern. • Follicular small cell cleaved cell lymphoma is common in bone marrow, although in most of the cases does not present as destructive bone tumor. • Similarly, chronic lymphocytic leukemia rarely present as tumefactive process. • Consquently, most of the bone lymphomas are diffuse large cell type. • It has characteristic permeative growth pattern. • Bony trabeculae may appear normal or may appear thickened or irregular, even Pagetoid. 92% of primary non-Hodgkin lymphoma of bone was found to be of the large B cell type and only 3% diffuse follicle centre cell, #% anaplastic large cell and 2% immunocytoma. • One problem with the diagnosis of lymphoma in bone is that the calls tend to get crushed. • If a bone biopsy shows such a crush artifact, a diagnosis of malignant lymphoma should be suspected. • Hodgkin lymphoma may involve the skeleton as a manifestation of a wide spread disease and produce a tumor mass but primary manifestations are rare. Prognosis: • Prognosis of lymphoma is assocuiated with cell type and stage of disease. • Patients older than 60 y/o have a worse overall survival and a worse progression-free period. • Patients with immunoblastic subtype has a worse survival than the centroblastic mono/polymorphic subtype or the centroblastic multilobulated subtype.
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CHONDROSARCOMA Definition: • Chondrosarcoma (CHS) is a malignant tumour with hyaline cartilage differentiation. • Myxoid changes, calcification or ossification may be present. Epidemiology: • Primary CHS accounts for approximately 20% of malignant bone tumours. • It is the third most common primary malignancy of bone after myeloma and osteosarcoma. • Tumour of adulthood and old age. • The majority of patients are older than 50 years. The peak incidence is in the fifth to seventh decades of life. • There is a slight preference for male. • Very rare in younger patients, although if in younger patients usually present as high grade. Sites of involvement: • Most common skeletal sites are the bones of the pelvis (the ilium is the most frequently involved bone) followed by the proximal femur, proximal humerus, distal femur and ribs. • The small bones of the hands and feet are rarely involved by primary CHS (1% of all CHS). • Extremely rare in the spine and craniofacial bones. Clinical findings: • Local swelling and pain, alone or in combination, are significant presenting symptoms. • The symptoms are usually of long duration (several months or years). Imaging: • In the long bones primary CHS occur in the metaphysis or diaphysis were the produce fusiform expansion with cortical thickening of the bone. • CHS produce fusiform expansion with cortical thickening of the bone. • CHS present as an area of radiolucency with variably distributed punctate or ring-like opacities(mineralization). • Cortical erosion or destruction is usually present. • Cortex is often thickened but periosteal reaction is scant or absent. • MRI can be helpful in delineating the extent of the tumour and establishing the presence of soft tissue extension. • CT scans aid in demonstrating matrix calcification. Gross: • Cut surfaces of CHS tend to have a translucent, blue-grey or white color corresponding to the presence of hyaline cartilage. • Lobular growth pattern is a consistent finding. • There may be zones containing myxoid or mucoid material and cystic areas. • Erosion and destruction of the cortex with extension into soft tissue may be present expecially in CHS of the flat bones pelvis, scapula and sternum). Histopathology: • Low magnification CHS shows abundant blue-grey cartilage matrix production. • Lobules of cartilage varying in size and shape are present. • Lobules may be separated by fibrous bands or permeate bony3 trabeculae. • CHS are hypercellular when compared to an enchondroma. • Chondrocytes are atypical varying in size and shape and contain enlarged, hyperchromatic nuclei. Extent of atypia is usually mild to moderate. • Binucleation is frequently seen. • Permeation of cortical and/or medullary bone is an important characteristic of CHS that can be used to separate it from enchondroma. • Myxoid changes or chondroid matrix liquefaction is a common feature of chondrosarcomas. • Necrosis and mitoses can be seen in chondrosarcoma, particularly in high grade lesions. • CHS in a small bone of the hand and foot are different. Increased cellularity, binucleated cells, hyperchromasia and myxoid change may all be present in enchondroma in this location. • The most significant histological feature of CHS involving the small bones is permeationthrough the cortex into soft tissue and a permeative pattern in the cancellous bone. • Chondrosarcomas are graded on a scale of 1-3 • Grade 1: Tumours are moderately cellular and contain hyperchromatic plumpnuclei of uniform size. Occasionally binucleated cells are present. The cytology is very similar to enchondroma. • Grade 2: Tumours are more cellular and contain a greater degree of nuclear atypia, hyperchromasia and nuclear size. • Grade 3 lesions are more cellular and pleomorphic and atypical than grade 2. Prognosis: • Five-year survival is 89% for patients with grade 1, the combined group of patients with grade 2 and 3 have a five-year survival of 53%. • Approximately 10% of tumours that recur have an increase in the degree of malignancy.
CARTILAGE PRODUCING TUMORS