A Rare Case of Pulmonary Papillary Adenoma in Old Aged Woman: A Brief Case Report

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/ by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Pulmonary papillary adenoma may be an unusual neoplasm of the lung. Since 1980 when Spencer et al. 1 first described two cases of papillary adenoma of the lung, 23 cases have been reported worldwide including one case in Korea. 2-4 Its rarity and shared histologic features of both benign and malignant tumors demand special attention for diagnosis, especially on the intra-operative consultation. 2 Herein, we report a case of papillary adenoma of the lung that histologically mimicked a carcinoid tumor and review the histologic findings with differential diagnoses. A 68-year-old female, who was undergoing preoperative evaluation for known rectal cancer, received percutaneous needle biopsy for a pulmonary nodule (Fig. 1A) and endobronchial sono-guided biopsy for enlarged mediastinal lymph nodes, which showed no evidence of metastasis. However, the core of the pulmonary nodule was composed of bland papillae-like structures lined with a single layer of uniform cuboidal cells, suspicious for carcinoid or low-grade epithelial neoplasm. On consideration of double primary pulmonary neoplasm, she received combined laparoscopic low anterior resection of the rec-tum and wedge resection of the left lobe of the lung. The resected specimen of lung contained a 2.5×1.5-cm-sized, peripherally located mass with a granular cut surface. At low power view, it is well demarcated without necrosis or hemorrhage (Fig. 1B). Microscopically, it showed dominant papil-lary architecture and focal microcystic area (Fig. 1C, D). The papillae contained prominent or delicate fibrovascular cores and were lined by monotonous cuboidal cells (Fig. 1E). The epithe-lial cells had moderate or small amount of cytoplasm and round, centrally located nuclei with inconspicuous nucleoli, and no nuclear atypia or mitosis was found (Fig. 1F). The chromatin was relatively uniformly distributed and finely granular, suspicious for neuroendocrine tumor. The microcystic area were lined with same epithelial cells and filled with amorphous eo-sinophilic material, similar to colloid or amyloid. For the differential diagnoses with papillary adenoma of lung, metastatic follicular or medullary carcinoma of thyroid gland and less likely metastatic adenocarcinoma of rectum, im-munohistochemical staining was performed. The tumor cells showed negativity for chromogranin The eosinophilic material was negative by Congo-red stain and polarizing microscopy. The patient was confirmed to have primary papillary adeno-ma of the lung and adenocarcinoma of …