Ciliated muconodular papillary tumor of the lung presenting with polymyalgia rheumatica-like symptoms: a case report.

Ciliated muconodular papillary tumors (CMPTs) of the lung have been recently characterized as low-grade malignant tumors and may be indistinguishable from adenocarcinoma in situ (AIS) because they are both abundant in mucous and spread along the alveolar walls. Herein, we report a case of CMPT with polymyalgia rheumatica (PMR)-like symptoms, which resolved after resection. After the surgery, antinuclear antibody tests were performed, but no abnormalities were noted. Furthermore, the lung tumor could not be distinguished from AIS, as revealed by a pathological examination. This case demonstrates two key points: the paraneoplastic symptoms of CMPT can indicate PMR, and it is difficult to diagnose peripheral lung tumors as CMPT unless there is a completely resected specimen available. The possibility exists that an increased number of older patients will be diagnosed with CMPT because of the increasing frequency of computed tomography performed in this population. Therefore, it is important for clinicians to obtain completely resected specimens to ensure accurate diagnosis and management of CMPT.