Primary cutaneous PEComa.

Area of Science:

• Dermatopathology
• Oncology
• Surgical Pathology

Background:

• Perivascular epithelioid cell tumors (PEComas) are rare mesenchymal neoplasms.
• PEComas can occur in various organs, with primary cutaneous PEComas being exceptionally rare.
• This study focuses on a case of primary cutaneous PEComa, contributing to the limited literature.

Observation:

• A solitary cutaneous nodule on the left lower leg was examined.
• Microscopic findings revealed nests of epithelioid cells with clear cytoplasm, vesicular nuclei, and a capillary network.
• Immunohistochemical analysis showed positivity for HMB-45 and microphthalmia-associated transcription factor (MITF), with focal desmin positivity.

Findings:

• The dermal tumor exhibited an infiltrative border without epidermal involvement.
• Periodic acid-Schiff stains confirmed glycogen deposition in the clear cells.
• The tumor cells were negative for S-100 protein, alfa smooth muscle actin, HHF-35, and cytokeratins, aiding in differential diagnosis.

Implications:

• This case adds to the approximately 22 reported cases of primary cutaneous PEComas in the English literature.
• The findings alert dermatopathologists to this distinctive and unusual neoplasm.
• Limited follow-up data suggests a benign clinical behavior for primary cutaneous PEComas.