[Pulmonary Adenocarcinoma with Heterotopic Ossification]

Although malignant tumor with heterotopic ossification have often been reported, it is very rare in lung cancer. We report a case of primary lung adenocarcinoma with heterotopic ossification.

A 43-year-old woman undergoing a health check was found an abnormal nodular lesion on chest X-ray. Chest computed tomography (CT) showed a calcified tumor, which was diagnosed adenocarcinoma by transbronchial biopsy. Right lower lobectomy and ND2a-2 lymph node dissection was done. Postoperative pathological examination identified the tumor as a bronchioloalveolar adenocarcinoma with other mixed subtypes, associated with ossification containing bone marrow tissue in the tumor. An immunohistochemical examination showed that cancer cells around the ossification expressed bone morphogenetic protein-2 and osteopontin, which generally induce and stimulate bone formation.

This finding may serve to elucidate a probable mechanism for the heterotopic ossification observed in cancer lesions.