異所性骨形成を伴った原発性肺腺癌

Pulmonary Adenocarcinoma with Heterotopic Ossification

悪性腫瘍に異所性骨形成を伴う報告が腎癌，肝癌，乳癌，皮膚癌，大腸癌などでは散見されるが1），原発性肺癌において異所性骨形成を伴うことはまれ2～10）と報告されており，そのため異所性骨形成の様式や成因，意義に関しては不明な点が多い．われわれは異所性骨形成を伴った原発性肺癌の1例を経験したので，若干の文献的考察を加えて報告する．

Background：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.

Case：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.

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