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[PEComa of soft tissue: report of an articular case]
Claire Bléchet1, Brigitte Arbeille, Anne de Muret
1Anatomie et Cytologie Pathologiques, Hôpital Bretonneau, CHRU de Tours, Tours Cedex 9.
Abstract:
We report a case of PEComa (or perivascular epithelioid cell tumor) in an unusual articular localization in a 13-year-old boy. The tumor, of 4 cm in diameter, showed an infiltrative pattern and was composed of both epithelioid and spindle cells with clear to granular eosinophilic cytoplasm and some multinucleated giant cells. Focal nuclear pleomorphism was present and we found up to 2 mitotic figures /50 high power field. There was no necrosis. Immunohistochemistry showed HMB-45 and smooth muscle actin positivity. Ultrastructurally, premelanosomes were present. Some rare cases of PEComa were reported in the soft tissues. The immunohistological profile (HMB-45 and smooth muscle actin positivity and PS-100 negativity) is helpful to the diagnosis. The histological prognostic criteria of these tumors are not well established. We discuss here the differential diagnosis, notably clear cell sarcoma of soft tissue.
Insights
This study presents a rare case of perivascular epithelioid cell tumor (PEComa) in a 13-year-old boy. The tumor
Area of Science:
- Oncology
- Pathology
- Pediatric Oncology
Background:
- Perivascular epithelioid cell tumors (PEComas) are rare mesenchymal neoplasms.
- PEComas typically occur in soft tissues, with articular localization being exceptionally uncommon.
Observation:
- A 4 cm PEComa was identified in an unusual articular location in a 13-year-old male patient.
- Histological examination revealed an infiltrative pattern with epithelioid and spindle cells, multinucleated giant cells, and focal nuclear pleomorphism.
- Immunohistochemistry demonstrated positivity for HMB-45 and smooth muscle actin, with negativity for PS-100.
Findings:
- The tumor exhibited characteristics consistent with PEComa, including specific immunohistochemical markers.
- Ultrastructural analysis confirmed the presence of premelanosomes.
- The case highlights the diagnostic utility of the immunohistological profile for PEComa.
Implications:
- This case expands the known spectrum of PEComa localization, emphasizing its potential occurrence in articular sites.
- Understanding the diagnostic criteria, including immunohistochemistry, is crucial for differentiating PEComa from other soft tissue tumors like clear cell sarcoma.
- Further research into the histological prognostic criteria for PEComas is warranted given their not well-established nature.