Tumor-like lesions of the ovary associated with pregnancy.

Six nonneoplastic ovarian lesions (or alterations) are associated with pregnancy or the puerperium, each of which can simulate a neoplasm on clinical, gross, or microscopic examination. These lesions include pregnancy luteoma, hyperreactio luteinalis, large solitary luteinized follicle cyst of pregnancy and puerperium, intrafollicular granulosa cell proliferations, hilus cell hyperplasia, and ectopic decidua. Because these lesions involute spontaneously after termination of pregnancy or are adequately treated by a conservative surgical approach, unnecessarily radical operations can be avoided if the correct diagnosis is made by the pathologist.