Intravenous leiomyomatosis with atypical histologic features: a case report.

Intravenous leiomyomatosis (IVL) is a rare smooth muscle tumor. We report a case of IVL with atypical histologic features, which did not respond to gonadotropin-releasing hormone agonists and could be only partially resected due to adherence to the vessel wall. Atypical histology may signify more aggressive behavior. IVL should always be considered when a patient presents with both uterine leiomyoma and venous thrombosis, and a high index of suspicion is crucial for early diagnosis. An adequate surgical preparation including venous graft or prosthetic reconstruction is essential as difficulty in removal may arise if the intravascular tumor adheres to the vessel wall.