Case Report: Pulmonary Benign Metastasizing Leiomyoma Appears 26 Years after Resection of Uterine Leiomyoma

Abstract

Benign metastasizing leiomyoma (BML) is a rare disease which usually presents as multiple pulmonary nodules several years (average 15 years) after the resection of uterine leiomyoma(s). Only about 100 cases of BML have been reported in English literature. Here we report an unusual case of BML identified 26 years after resection of uterine leiomyoma.  The patient was a 44-year-old woman who was found to have an incidental lung nodule in the left lower lobe of lung during workup for a brain lesion that was biopsy-proven astrocytoma.  A lung wedge resection was performed and a solid, well demarcated, 2.5 x 1.5 x 1.5 cm nodule was resected. The lesion was composed of bland appearing spindle cells without mitotic activity that were positive for smooth muscle actin, estrongen receptor and vimentin. CD117, S100, Synaptophysin, HMB-45, CD99, calretinin, pancytokeratin and CD10 were negative. MIB-1(Ki-67) staining showed very low proliferative index. In conclusion, the overall morphological and immunohistochemical features, and patient's remote history of primary uterine leiomyoma supported the diagnosis of pulmonary BML.