Soft Tissue Pathology
Pathology of Extraskeletal Chondro-Osseous Tumours
Pathology of Extraskeletal
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
Tumoral calcinosis - (no cartilage, histocytic response to calcified
| 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.
- 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.
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