A rare case of small cell lung carcinoma combined with rhabdomyosarcoma

Abstract

Background. Combined small cell lung carcinoma (CSCLC) is histologically classified as small cell lung carcinoma (SCLC) containing non-small cell carcinoma. CSCLC mostly contains large cell neuroendocrine carcinoma or adenocarcinoma but rarely contains sarcoma. We report a rare case of CSCLC containing rhabdomyosarcoma. Case. A 75-year-old man with interstitial lung disease was diagnosed with small cell lung carcinoma (SCLC; cT2aN1M1a Stage IV) by bronchoscopy. He received a course of sequential chemotherapy (cisplatin and etoposide) and three courses of sequential chemotherapy (carboplatin and etoposide). The treatment resulted in a partial remission, and the patient was followed up. After eight months, the patient was admitted for progressive dyspnea. Chest computed tomography (CT) showed a diffuse lesion of elevated density in the left lung. He was diagnosed with an acute exacerbation of interstitial pneumonia and was treated with methylprednisolone pulse therapy (1000 mg/day). Despite being given methylprednisolone pulse therapy twice, the patient died of progressive respiratory failure. At autopsy, an examination of the lungs showed that a portion of the SCLC contained multinucleated cells; immunohistochemistry revealed that this region was positive for desmin and myoD1. These results indicated that the multinucleated cells represented rhabdomyosarcoma. Based on the results of a histopathological examination, we diagnosed CSCLC with an element of rhabdomyosarcoma. According to previous reports in the literature, cases of CSCLC containing rhabdomyosarcoma are very rare. Conclusion. It is possible for CSCLC to contain multiple types of cancer. Consequently, it is very important to diagnose CSCLC, in order to select the most appropriate therapy and to estimate the prognosis as accurately as possible.