Unusual case of uterine intravascular leiomyomatosis with lymphatic spread to pelvic lymph nodes.

Intravascular leiomyomatosis is a rare disease characterized by extension of benign smooth muscle proliferation into uterine and pelvic vessels. The involved vessels are almost always veins and rarely lymphatics. Intraarterial growth has not been described. Intravascular leiomyomatosis can show different morphologic features that are commonly described in leiomyomas. The differential diagnosis includes endometrial stromal sarcoma, lymphangioleiomyomatosis and leiomyosarcoma. Immunohistochemistry is helpful to establish a correct diagnosis. The condition is histologically benign; however, these lesions can spread by the venous system into the inferior vena cava, heart, and lungs. Treatment of this condition is surgical. The spread of intravenous leiomyomatosis exclusively by uterine lymphatics to the pelvic lymph nodes has not been previously reported.