Table 1.

Classification of malignant potential for non-gynecologic PEComas (adapted from [12])

High risk features	Risk category
(1) Size > 5 cm (2) Infiltrative growth pattern (3) High nuclear grade and cellularity (4) Mitotic Rate > 1/50 HPF (5) Necrosis (6) Vascular invasion	• “Benign”: < 2 high risk features and size < 5 cm • “Uncertain malignant potential”: Size ≥ 5 cm with no other high risk features OR nuclear pleomorphism/multinucleated giant cells only • “Malignant”: ≥ 2 high risk features