Pulmonary papillary adenoma with malignant potential: a case report and literature review.

Background: Pulmonary papillary adenoma is a rare benign tumor in the periphery of the lung. We report a 66-year-old female patient with a tumor in the lower lobe of the right lung and present the clinicopathological features and review the literature.

Case Presentation: A tumor in the lower lobe of the right lung was found incidentally on chest X-ray during the physical examination of the patient, and the patient occasionally had a dry cough that was not treated. The tumor was clearly demarcated and lobulated on CT scan. After 2 years of follow-up, the boundary of the tumor was still clear, with more lobulations and the enhanced scan showed uniform enhancement. Grossly, the tumor had a granular cut surface and was easy to fall off, which was helpful for the diagnosis of papillary adenoma during intraoperative frozen examination. Under the microscope, most areas of the tumor had the typical morphological structure of papillary adenoma. However, the tumor locally protruded into the surrounding lung tissue, accompanied by crowded cells and high cell proliferation index. It was suggested that this case of papillary adenoma had malignant potential and needed active intervention and treatment.

Conclusion: Pulmonary papillary adenoma is a rare epithelial tumor with malignant potential. Surgical treatment should be performed as soon as possible after diagnosis to prevent malignant transformation.