A surgical Case of Synchronous Multiple Primary Lung Cancers with Small Cell Carcinoma and Squamous Cell Carcinoma

The incidence of synchronous multiple primary lung cancers has increased in recent years, however, there are few reports of cases involving small cell carcinoma. A 72-year-old man was referred to our department because of an abnormal shadow on chest radiography. He was receiving treatment for pulmonary fibrosis, emphysema, rheumatoid arthritis, and prostate cancer. Computed tomography revealed two lung nodules in the left lower lobe. A definitive diagnosis was unable to be made based on transbronchial lung biopsy. Positron emission tomography demonstrated abnormal fluorodeoxyglucose uptake in the two lung nodules and lung cancer (cT3N0M0) was suspected. Thoracoscopic partial resection of the left lower lobe was performed. As primary lung cancer was diagnosed using the frozen specimen, we performed left lower lobectomy with lymph node dissection. Pathological examination of the S9 and S6 tumors revealed combined small cell carcinoma and squamous cell carcinoma, respectively. Both tumors were separated and diagnosed as synchronous multiple primary lung cancers. No lymph node metastasis was found. We report a rare case of synchronous multiple primary lung cancers, including small cell carcinoma.