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 Soft Tissue Pathology

Pathology of Extraskeletal Chondro-Osseous Tumours

 Dr Sampurna Roy MD  

 

Pathology of Extraskeletal Chondroma 

 

Age - This tumour usually occurs in adults, between 30 and 60 years.

Site - Usually located on the hands and feet .

Gross - Firm, well demarcated, lobulated lesion, not more than 3cm in maximum diameter.

Microscopic features -

- Well circumscribed, multinodular tumour.

- Consists of mature hyaline cartilage.

- Focal fibrosis, ossification or myxoid changes may be noted in some cases.

- Richly vascular interlobular connective tissue is often noted.

- Focal or diffuse calcification may be a late feature.

- Floccular or granular calcified material may outline the chondrocytes (lace-like pattern).

- Calcification more prominent at the centre than the periphery of the tumour .

- Cacification may be accompanied by degeneration and necrosis in some cases.

- Focal granuloma like proliferation of epitheloid cells & multinucleated giant cells may be present.

- In a few cases immature cells with atypical features may be present. These lesions do not behave differently from the benign lesions with usual features.

Immunohistochemistry-  S100 protein and vimentin positive

Differential diagnosis-

Tumoral calcinosis - (no cartilage, histocytic response to calcified material),
Myxoid Chondrosarcoma (extremely rare in hands & feet);
Calcifying aponeurotc fibroma (cartilage in a dense fibrous backround)

 

Further reading

Extraskeletal chondroma of the fallopian tube.

Chondroblastoma-like chondroma of soft tissue: an underrecognized variant and its differential diagnosis.

Intracapsular and para-articular chondroma adjacent to large joints: report of three cases and review of the literature.

Extraskeletal chondroma of the hand. Case report and review of the literature.

Soft tissue chondroma of the parapharyngeal space: a case report.

Extraskeletal chondroma, a rare soft tissue tumor. Case report.

Fine needle aspiration cytology of soft tissue chondroma. A case report.

Extraskeletal chondromas.

Diagnosis and differential diagnosis of extraskeletal, para-articular chondroma of the knee.

Extraskeletal chondroma with chondroblastic and granuloma-like elements.

Childhood soft tissue chondroma: a case report.

Involvement of chromosomes 6 and 11 in a soft tissue chondroma.

 

 Extraskeletal Myxoid Chondrosarcoma (Chordoid Sarcoma)

 

Extraskeletal myxoid chondrosarcoma is a rare locally aggressive low-grade soft-tissue sarcoma with a high potential for metastasis, especially to the lungs. 

It tends to metastasize more frequently than skeletal myxoid chondrosarcoma but is biologically less aggressive.

Age - Extraskeletal myxoid chondrosarcoma usually occurs in adults. 

Site -  These are located in the deep tissue of the extremities, specially in the musculature and rarely on the trunk, neck, mediastinum and retroperitoneum. 

Gross- Lobulated, well circumscribed mass.

Microscopic features-

- Multinodular tumour.

- Consists of cords and strands of small ovoid cells with eosinophilic cytoplasm and  round nuclei set in a myxoid matrix (lace-like growth pattern).

- Hyaline rhabdoid inclusions may be present  (some of these cells are CAM5.2 and vimentin positive).     

- Hypercellular areas are noted at the periphery.

- In some cases the entire tumour is diffusely cellular and the cells are more spindle shaped.

- The tumour cells contain glycogen (PAS postive). Myxoid matrix is alcian blue positive.

Immunohistochemistry- S100 protein positive. Some cases are EMA positive.

The tumour cells are usually negative for keratins. (Synaptophysin, NSE, PGP9.5 may be positive in a few cases).

Differential diagnosis-    Myxoid Tumours of Soft Tissue

The differential diagnoses of Extraskeletal myxoid chondrosarcoma  include skeletal myxoid chondrosarcoma, chordoma, parachordoma, mixed myoepithelial tumor, and other myxoid soft tissue lesions.

Skeletal myxoid chondrosarcoma can closely mimic Extraskeletal myxoid chondrosarcoma.

Mixed tumour of soft tissue shows epithelial differentiation (keratin, actin and S100 protein-positive).  

Chordoma and parachordoma can be differentiated from Extraskeletal myxoid chondrosarcoma by the presence of physaliferous cells and epithelial markers.

Extraskeletal myxoid chondrosarcoma is distinguished from other myxoid soft tissue lesions by its location and distinctive morphologic features.

Cytogenetics- The tumour shows chromosomal translocation  t(9:22)(q22:q12).

The least cellular and most myxoid tumours carry the best prognosis.

Further reading:

Extraskeletal myxoid chondrosarcoma: Updated clinico-pathological and molecular genetic characteristics.

Extraskeletal myxoid chondrosarcoma: a clinicopathologic, immunohistochemical, and ploidy analysis of 23 cases

Extraskeletal myxoid chondrosarcoma: a reappraisal of its morphologic spectrum and prognostic factors based on 117 cases.

Extraskeletal myxoid chondrosarcoma: a light microscopic, immunohistochemical, ultrastructural and immuno-ultrastructural study indicating neuroendocrine differentiation.  

Fusion of the EWS-related gene TAF2N to TEC in extraskeletal myxoid chondrosarcoma.

Extraskeletal myxoid chondrosarcomas do not show a chondrocytic phenotype.

Extraskeletal myxoid chondrosarcoma: a clinicopathologic, immuno-histochemical, and molecular analysis of 18 cases.

 

Pathology of Extraskeletal Osteosarcoma

 

Malignant mesenchymal neoplasm that produces osteoid, bone or chondroid material and is located in the soft tissues without attachment to the skeleton.

This is an aggressive tumour with over 60% mortality rate.

Age: The tumour usually occurs in late adult life (6th and 8th decade of life).

Site: Lower extremities are most commonly affected , other sites include retroperitoneum and muscles of the pelvic and shoulder girdles.

Gross: Macroscopically the tumour is a firm to stony hard mass. Sectoning may reveal granular white with yellow flecks and multiple foci of haemorrhage.

Radiologically:  Extraskeletal osteosarcoma manifests as a soft tissue mass with spotty to massive calcification.

There is no evidence of bone involvement.   

Microscopic features:   Like osteosarcoma of the bone the histologic patterns include osteoblastic, chondroblastic, fibroblastic, MFH-like, telangiectatic and well differentiated types.

In soft tissue,  MFH-like osteosarcoma is the commonest variant.  

Differential diagnosis:  Myositis ossificans (presence of histological zoning and lack of prominent atypical features).

Soft tissue tumours with metaplastic bone formation (Synovial sarcoma;  Malignant fibrous histiocytoma ; Fibrosarcoma).

 

Further reading:

Extraskeletal osteosarcomas: a clinicopathologic study of 25 cases.

Extraskeletal osteosarcoma.

Well-differentiated extraskeletal osteosarcoma:report of 2 cases,1 with dedifferentiation.

Extraskeletal osteosarcoma histologically mimicking parosteal osteosarcoma.

A low-grade extraskeletal osteosarcoma.

Extraskeletal retroperitoneal osteosarcoma. A case report and review of the literature.

 

 

Dr Sampurna Roy  MD

Consultant  Histopathologist (Kolkata - India)


 

 

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