[Two Patients with Ciliated Muconodular Papillary Tumor Whose Preoperative Diagnosis Was Difficult]

Ciliated muconodular papillary tumors (CMPT) are rare lung tumors characterized by the papillary proliferation of ciliated and goblet cells. We report 2 patients with CMPT following surgical resection of pulmonary nodules who showed increased shadowing after malignant tumor treatment. The first patient, a male in his 70s, was referred for an enlarging nodule in the right middle lobe of the lung detected during a postoperative follow-up for sigmoid colon cancer. Contrast-enhanced chest computed tomography (CT) revealed an 11 mm irregular nodule in the right middle lobe. Wedge resection was performed using video-assisted thoracic surgery. The intraoperative rapid diagnosis was adenocarcinoma, but the permanent specimen was diagnosed as CMPT. The second patient, a woman in her 80s with a history of left-sided breast cancer, was referred for evaluation of a nodule in the left upper lobe of the lung detected on plain CT. A plain chest CT revealed a 10 mm nodule in the left upper lobe. A segmentectomy of the upper division of the left lung was performed. Intraoperative rapid diagnosis revealed that the mass was of unknown nature, but the permanent specimen was diagnosed with CMPT. CMPT is difficult to diagnose preoperatively and intraoperatively. In patients with malignant tumors, definitive surgical resection is necessary for differential diagnosis.