Perinodular hydropic degeneration of a uterine leiomyoma: a diagnostic challenge.

Perinodular hydropic degeneration of a uterine leiomyoma is a rare form of the more common hydropic change observed in leiomyomas. With minimal discussion in the surgical pathology literature, appropriate evaluation may be challenging because the differential diagnosis includes other uncommon uterine disorders such as intravenous leiomyomatosis, diffuse leiomyomatosis, myxoid leiomyosarcoma, endometrial stromal sarcoma, angiofibroma, and angiomyxoma. We describe such a diagnostic challenge in a 42-year-old woman with a left adnexal mass discovered during an annual examination. With only three cases of perinodular hydropic degeneration previously reported, this case is the first with extrauterine extension and was initially concerning for a more aggressive process.