Desmoid tumor requiring differentiation from port-site relapse after surgery for lung cancer.

Thoracoscopic left lower lobectomy with lymph node dissection for lung cancer was performed in a 76-year-old man. The diagnosis was pT2aN2M0 adenocarcinoma. Sixteen months after surgery, CT revealed a pleural tumor measuring 38 mm at the surgical port wound. CT-guided biopsy revealed fibroma. However, the tumor size increased 4 months after biopsy, and surgery was performed. An intraoperative diagnosis revealed benign fibroma. Thoracoscopic tumorectomy was conducted. The pathological diagnosis was desmoid tumor. As the margins of the resected specimen were positive, radiotherapy was performed. During the 16-month follow-up period, there has been no relapse. Pleural desmoid tumors must be differentiated from port-site relapse.