Patient selection: women with leiomyoma and a history of recent or current therapy with a progesterone compound
Histologic features that may be confused with a malignancy:
(1) areas of necrosis (usually infarct-type but occasionally resembling tumor necrosis)
(2) mitotic activity in smooth muscle cells adjacent to the areas of necrosis
(3) increased cellularity
Key diagnostic features:
(1) history of progesterone therapy
(2) lack of true nuclear atypia
(3) low mitotic activity in the leiomyoma away from areas of necrosis
Additional features may include:
(1) cytoplasmic eosinophilia
(2) nuclear pyknosis
(3) epithelioid morphology
(4) stromal edema
(5) hemorrhage
(6) myxoid change
(7) lymphocytic infiltrate (granular cytoplasma, CD56 positive)
