Intravascular Leiomyomatosis: Benign Histology with Aggressive Behavior

Intravascular leiomyomatosis is a rare benign smooth muscle neoplasm characterized by intravascular proliferation of smooth muscle tissue, with the potential to extend beyond the uterus into the pelvic venous system and, in advanced cases, the cardiopulmonary circulation. Despite its benign histologic appearance, intravascular leiomyomatosis may exhibit aggressive clinical behavior and frequently poses a diagnostic challenge. We present the case of a 27-year-old woman with no prior pregnancies underwent laparoscopic excision of a leiomyoma. Fifteen months later, MRI identified a left broad ligament mass with intermediate T2 signal intensity and cystic areas, abutting the rectosigmoid and extending into the parametrium and paracolpium, as well as a necrotic internal iliac lymph node. Restricted diffusion and heterogeneous enhancement raised concern for malignancy. Laparoscopic excision revealed masses: one extending from the left mesosalpinx into the parametrium and another from the parametrium to the vesicouterine space, with involvement of the uterine artery. Histopathology revealed smooth muscle proliferation with fascicular architecture within dilated parauterine and parametrial vessels, with hypercellular areas without atypia, necrosis or mitotic activity but extensive cystic and hydropic change confirming intravascular leiomyomatosis (IVL). Although histologically benign, intravascular leiomyomatosis may present with suspicious imaging findings and invasive biological behavior. This case highlights the importance of correlating radiologic, surgical, and histopathological findings to ensure an accurate diagnosis and appropriate therapeutic management. KEYWORDS: Uterine leiomyoma; intravascular leiomyomatosis; magnetic resonance imaging; uterine masses; vascular neoplasms.