Uterine PEComas mimic leiomyosarcoma and other sarcomas. Start with morphology: epithelioid or clear cells around vessels. Then pair a sensitive marker such as GPNMB with melanocytic markers (HMB-45, melan-A, cathepsin K) and smooth muscle markers. If the picture is mixed, consider TFE3 immunohistochemistry or molecular testing for TSC2 or TFE3 rearrangement before committing.
- Look for perivascular epithelioid or clear cells on morphology first.
- Stain HMB-45, melan-A and cathepsin K alongside smooth muscle markers.
- Use GPNMB to rule out, not to confirm.
- Send TFE3 or TSC testing when markers conflict, as it can open mTOR-targeted therapy.
Why it matters
PEComa and leiomyosarcoma have different prognoses and systemic options.
Read the rest in the app
You have read your two free briefings this month. The app carries all 27 specialties, every morning, free — and this finding is waiting in it.
Scan to keep reading on your phone. No account needed to start.
Tomorrow morning, before your first patient
One edition a day for pathology, written by the desk, every claim tied to its paper. Six minutes.
Get the app — free