[A case of pulmonary fibroma]

A 42-year-old man without symptoms was admitted to the hospital because of a well-circumscribed mass in his left upper lung field, which was found on a routine chest X-ray film. CT of the chest revealed a well-defined homogeneous mass in the left upper lobe. Bronchial biopsy yielded material unsatisfactory for diagnosis. On thoracotomy a tumor, entirely within the lung parenchyma, was found to occupy S3. Due to its size and location left upper lobectomy was done. Histologically, the tumor contained interlacing bundles of spindle cells compatible with fibroma, with no indicators of malignancy. Intrapulmonary fibromas are rare and only one report could be found in the Japanese literature.