Primary smooth muscle tumor of the pleura: a clinicopathological case report with ultrastructural observations and a review of the literature.

Primary smooth muscle tumor of the pleura is exceptionally rare. The authors describe a primary smooth muscle tumor of the pleura that was discovered incidentally on chest X-ray in a 73-year-old man. Magnetic resonance imaging demonstrated a 12 x 18 x 15-cm pleura-based mass arising from the posterior mediastinum. Computerized tomography (CT) guided needle cores from the pleura showed a primary smooth muscle tumor of undetermined malignant potential. Further excision of the whole tumor showed an intimate relation to pleura, and the diagnosis of leiomyosarcoma was made. The clinical, radiological, histopathological, immunohistochemical, and ultrastuctural findings were consistent with a primary smooth muscle tumor of the pleura. This is the seventh case in the literature of a primary smooth muscle tumor of the pleura, which, to the best of the authors' knowledge, is the first such case of the pleura to be diagnosed on CT-guided needle biopsy. In conclusion, this method of investigation is recommended since it is minimally invasive but has a rewarding yield in providing the most likely diagnosis, predicting prognosis, and management planning.