Clinical characteristics and outcomes of patients with hepatic angiomyolipoma: A literature review

Table 2 Classification of perivascular epithelioid cell tumors according to their malignant potential[1,27]

Classification	Criteria
Benign	No worrisome features: (1) Tumor size < 5 cm; (2) No infiltration; (3) Non-high nuclear grade and cellularity; (4) Mitotic activity ≤ 1/50 HPF; (5) No necrosis; and (6) No vascular invasion
Uncertain malignant potential	Tumor with: (1) Pleomorphism/multinucleated giant cells only; or (2) Size > 5 cm only
Aggressive behavior	Two or more worrisome features: (1) Size > 5 cm; (2) Peripheral infiltration; (3) High nuclear grade and cellularity; (4) Mitotic activity > 1/50 HPF; (5) Ischemic tumor necrosis for large tumor; and (6) Vascular invasion
According to the WHO classification of tumors[1]	As with GISTs, the main predictors of a risk of metastatic behavior are marked nuclear atypia, diffuse pleomorphism and mitotic activity of more than 1 mitosis per 1 mm²

GIST: Gastrointestinal stromal tumor; HPF: High-power field.