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Copyright ©The Author(s) 2021.
World J Gastroenterol. May 21, 2021; 27(19): 2299-2311
Published online May 21, 2021. doi: 10.3748/wjg.v27.i19.2299
Table 2 Classification of perivascular epithelioid cell tumors according to their malignant potential[1,27]
Classification
Criteria
BenignNo 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 potentialTumor with: (1) Pleomorphism/multinucleated giant cells only; or (2) Size > 5 cm only
Aggressive behaviorTwo 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