[1018] Apoplectic Change in Uterine Leiomyomas: An Analysis of 70 Cases Highlighting Previously Underemphasized Aspects

CA Lamb, RH Young. Massachusetts General Hospital, Boston, MA

Background: Previous literature has drawn attention to a limited constellation of findings often seen in leiomyomas from patients who have received progestin therapy, termed apoplectic leiomyomas. These changes are stellate zones of hemorrhage with small foci of necrosis surrounded by hypercellular regions with increased mitotic rate. Our experience has indicated that additional frequent findings not emphasized to date may be a clue to the diagnosis and, if misinterpreted, may lead to an erroneous classification.
Design: All available cases of uterine leiomyoma with apoplectic change submitted to a consultant for a second opinion were reviewed.
Results: Patients ranged in age from 23-66 years (average 41). Of the 57 cases with available gross descriptions, 74% had atypical features; foci of hemorrhage (49%), discoloration (23%), softening (19%), cystic change (18%), and necrosis (18%). Microscopic findings of concern for the submitting pathologist were specified in 65 cases and included increased mitoses (66%), atypia (53%), hypercellularity (40%), necrosis (42%), pyknosis (11%), epithelioid morphology (11%), and mucinous/myxoid change (6%). Characteristic microscopic features seen in essentially all cases included multifocality, variable size, and stellate to oval configuration. Additional features frequently observed were zonal hypercellularity (81%), hemorrhage (81%), zonal necrosis (70%), individual cell necrosis/pyknosis (89%), hyalinization (81%), edema (56%), mucinous to myxoid matrix (30%), and cysts (30%). Mitotic activity in the smooth muscle at the periphery of the apoplectic regions was categorized as low (0-1/10 hpf) in 44%, moderate (2-5/10 hpf) in 30%, and brisk (>5/10 hpf) in 26%. Findings that were occasionally seen but not striking overall were slight nuclear atypia, vascular alterations, fibrin deposition, hemosiderin-laden or foamy macrophages, and tearing artifact. True epithelioid morphology was not identified.
Conclusions: Previously underemphasized findings common in apoplectic leiomyomas include lack of the characteristic hemorrhage and/or zonal hypercellularity, extensive regions of zonal necrosis, abundant pyknosis often mistaken for epithelioid morphology, central hyalinization or edema, focal mucinous to myxoid appearance (causing concern for myxoid leiomyosarcoma), cystic degeneration, and mitotic rate >5/10 hpf. Knowledge of this expanded spectrum of features is essential for recognizing variants of apoplectic change and avoiding a misdiagnosis of malignancy.
Category: Gynecologic

Tuesday, March 10, 2009 11:00 AM

Platform Session: Section D, Tuesday Morning