Solitary pleural metastasis in rectal cancer.

Pleural metastasis in rectal cancer is often due to secondary invasion or dissemination from intrapulmonary metastases. To date, there are no reports on solitary pleural metastasis. Here, we report a rare case of lower rectal cancer that recurred as pleural metastasis 4 years after surgical resection of the primary tumor. He was a 65-year-old man who visited our department with an abnormal shadow on his chest X-ray. He had a history of lower rectal cancer and had undergone laparoscopic low anterior resection of the rectum and bilateral lymph node dissection after neoadjuvant chemotherapy. Pathological ypT3N1M0 stage IIIA tumor was diagnosed, and adjuvant chemotherapy was administered. According to the computed tomography scan, a pleural tumor or pulmonary metastasis was suspected. Thoracoscopic partial resection of the lung and a partial pleurectomy were performed for diagnostic and therapeutic purposes. Histopathological examination revealed a highly differentiated tubular adenocarcinoma, consistent with metastatic rectal cancer. The nodule arose from the visceral pleura and invaded the parietal pleura with few malignant cells in the lung parenchyma. The lesion was surgically resected. However, 3 months after the second surgery, tumor recurrence with pleural dissemination was observed, and chemotherapy was initiated.