A rare case of ciliated muconodular papillary tumor accompanied with adenocarcinoma in situ

BACKGROUND: Ciliated muconodular papillary tumor (CMPT) is an incredibly rare pulmonary tumor. Currently, little is known about CMPT, and it has not yet been classified by the World Health Organization. The clinical manifestation of CMPT is nonspecific and the diagnosis is only based on pathology. CMPT has been documented in limited reports as a benign tumor, thus the treatment is typically with surgical excision if a solid tumor is identifiable. The prognosis of CMPT is very positive, as no recurrence has been reported in the limited literature available. However, CMPT accompanied with adenocarcinoma in situ has not been reported previously in the literature. CASE PRESENTATION: In this report, we presented a case of a 53-year-old male smoker with CMPT associated with adenocarcinoma in situ. This diagnosis was confirmed by pathological examination, including immunohistostaining. No solid resectable lesion was identified on CT scan; therefore, no surgery was performed. The patient’s adenocarcinoma in situ was disseminated in both lungs, thus chemotherapeutic treatment with cisplatin and pemetrexed was given. The patient will be continually followed up closely on a wait-and-watch basis. CONCLUSIONS: In summary, our report reveals a unique case of CMPT in conjunction with adenocarcinoma in situ, potentially revealing an association between CMPT and malignancy which has not been previously reported. More similar case studies will be beneficial to determine the authentic relationship between CMPT and adenocarcinoma in situ. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12890-021-01581-9.