Ciliated Muconodular Papillary Tumor of the Lung: A Newly Defined Low-grade Malignant Tumor with CT Findings Reminiscent of Adenocarcinoma

A ciliated muconodular papillary tumor has been reported to be a peripheral low-grade malignant tumor, consisting of ciliated columnar cells and goblet cells with basaloid cell proliferation. Although ciliated muconodular papillary tumors have not yet been classified according to the World Health Organization classification, they can pose diagnostic and therapeutic problems. Here we report a resected case of ciliated muconodular papillary tumor with computed tomography findings reminiscent of adenocarcinoma, showing a small irregular nodule adjacent to the intersegment pulmonary vein. There was no uptake of F-18 fluorodeoxyglucose positron emission tomography. The patient underwent surgical resection, and a lobectomy was performed because intraoperative needle biopsy suggested neoplastic proliferation. No EGFR mutations were detected. No recurrence was noted during 24-month follow-up after lobectomy.