Schoolmeester criteria for prognosis in PEComa (from Schoolmeester et al20)
| Criteria | Cases with known metastasis meeting criteria (%) | Cases without known metastasis meeting criteria (%) | |
|---|---|---|---|
| Benign or uncertain malignant potential | Tumours with less than four features: gross size ≥5 cm, high-grade nuclear features, necrosis, vascular invasion, or a mitotic rate greater than or one per 50 HPF | 0 of 9 (0) | 7 of 7 (100) |
| Malignant | Tumours with four or more features | 9 of 9 (100) | 0 of 7 (0) |
HPF, high power field; PEComas, perivascular epithelioid tumours.