Retrospective study of clinical and pathologic features of pulmonary papillary adenoma: A rare tumor and 15 cases report.

Pulmonary papillary adenoma is extremely rare. The limited number of published articles describing pulmonary papillary adenoma emphasize that it is always detected by physical examination, is difficult to diagnose, and has malignant potential. To further expand our understanding of this disease, we report on 15 cases of pulmonary papillary adenoma diagnosed from 2013 to 2019 in our hospital.The clinical and pathological data of 15 cases of pulmonary papillary adenoma were collected from the medical record system of our hospital. All the clinical data were checked by 2 independent researchers. All pathology outcomes were independently reassessed by 2 pathologists. A review of the relevant literature was performed.Of 15 patients identified, 6 were men and 9 were women, and the average age at disease onset was 61.3 years. Chest computed tomography (CT) indicated pneumonia, an isolated nodule, bronchiectasis, a mass, ground glass opacity, and local interstitial fibrosis under the pleura. Thirteen cases had benign histopathology upon microscopy and immunohistochemistry examination: a papillary morphology, grade 2 or 3 papillary branches, and a slender nipple axis composed of fibers and vessels. More than 80% of the papillary epithelial cells were columnar or cubic, and single-layered or pseudostratified, with a round nucleus at the bottom of the cell. The cytoplasm was rich in mucus and neutral mucopolysaccharides. Except the above-mentioned features, there was also local epithelial dysplasia, carcinogenesis, and interstitial infiltration in two cases. The 2 patients with a cancerous mass underwent surgical resection, whereas the other patients were kept under surveillance. While one patient with cancer is deceased, follow-up indicates that the remaining patients have experienced a good outcome.Pulmonary papillary adenoma is very rare in clinical practice, and its clinical manifestations and CT images are not specific. Some cases may be cancerous and surgical resection should be the preferred treatment.