[1619] Pulmonary Smooth Muscle Neoplasms: A Clinicopathologic Study

H Mani, K Shilo, M Miettinen, JR Galvin, TJ Franks. Armed Forces Institute of Pathology, Washington, DC; University of Maryland School of Medicine, Baltimore, MD

Background: Pulmonary smooth muscle neoplasms are rare. We present a study of 51 low-grade pulmonary leiomyomatous tumors, the largest series to date.
Design: All pulmonary spindle cell tumors accessioned to our consultation service from 1972 to 2004 were retrieved. Low-grade smooth muscle tumors including leiomyomas, lipoleiomyomas and low-grade leiomyosarcomas were selected. Clinical histories, radiology reports, gross descriptions and histology slides were reviewed.
Results: Fifty-one cases included 7 men and 44 women ranging in age from 32-72 years, mean 48 years. Tumors were found incidentally in 74% (26/35) of cases. Fifty-nine percent (29/49) of patients had multiple tumors. All 7 men and 31% (13/42) of women had single tumors. Twenty-seven women had a history of uterine fibroids; 2 of these were identified following discovery of lung lesions, while in 25, the uterine fibroids had been diagnosed 2-18 years prior to lung lesions. Uterine fibroids were more commonly associated with multiple than single tumors (69% vs 23%). All patients with a history of mitotically active uterine leiomyomas (2) and/or intravenous leiomyomatosis (4) had multiple tumors. Tumors ranged in size from 0.4-10 cm, mean 2.2 cm, and were well-circumscribed. Five cases had small cystic areas visible on imaging or gross examination, while an additional 18 cases showed dilated to microcystic entrapped glands on microscopy. There were 43 leiomyomas, 7 lipoleiomyomas and 1 low-grade leiomyosarcoma. Forty-nine percent (25/51) of tumors showed prominent collagenization. Twenty cases were classified as benign metastasizing leiomyomas based on the presence of multiple tumors and a history of uterine fibroids. Among 41 patients with available demographic information, one patient died at 17 months and 8 died 14-24 years after diagnosis. Sixty-six percent (6/9) of those who died were women; all 6 had uterine fibroids and 5 had multiple lung tumors.
Conclusions: Low-grade pulmonary smooth muscle tumors are usually discovered incidentally and occur predominantly in women. Their association with uterine fibroids (recent or remote) and prolonged survival, even in the setting of multiple tumors, suggests that benign metastasizing leiomyomas are a distinct clinicopathologic entity. The solitary lesions in men likely represent primary neoplasms.
Category: Pulmonary

Monday, March 9, 2009 1:00 PM

Poster Session II # 219, Monday Afternoon