Alveolar adenoma: a rare benign tumour of the lung with a challenging diagnosis

Abstract

Alveolar adenoma is a rare lung benign tumour originating from type II pneumocytes. It presents as a well-defined nodule. In some cases, it is difficult to differentiate from lung cancer. Few cases of this tumour have been reported. We describe here a case of alveolar adenoma in a 63-year-old man discovered incidentally on chest X-ray. The lesion was reported as lepidic adenocarcinoma in bronchoscopic biopsy. The patient underwent a thoracoscopic left lower lobectomy. The histopathological and immunohistochemical examinations resulted in a diagnosis of alveolar adenoma. We report this case to describe its morphological and immunohistochemical characteristics and to emphasize its diagnostic difficulties.

Enlarging pulmonary cyst: a rare form of alveolar adenoma

“…It is considered benign, and accounts for < 1% of all lung tumours [ 5 ]. Roughly 33 published reports with 60 cases have appeared in the English medical literature [ 6 , 7 ]. The first description was supplied by Yousem et al in 1986 [ 8 ].…”

“…Grossly, as in our case, these are well-demarcated subpleural or intraparenchymal lesions. Histologic preparations show ordinary cystic walls lined by flattened or cuboidal epithelial cells [ 6 ].…”

Alveolar Adenoma: A 20-Year Experience at a Western Balkan University Hospital and a Literature Review

“…4 Surgical methods were the best choice for both diagnosis and treatment. According to most cases from the literature, alveolar adenomas were treated video thoracoscopically, 2,4,10,11,14 but in some patients, thoracotomy was also performed. Usually, the reason for the thoracotomy was the anatomical localization of the tumor (central localization or the tumor was inseparable from a large blood vessel).…”

“…12 Areas of small and compacted cystic spaces in alveolar adenoma might simulate atypical adenomatous hyperplasia and adenocarcinoma in situ, but there is an absence of cytologic atypia. 10 The well-circumscribed growth pattern, lack of lepidic growth, cytologic atypia, and mitosis are helpful features that discern alveolar adenoma from lepidic predominant adenocarcinoma. The histology of atypical adenomatous hyperplasia and adenocarcinoma in situ indicates, in addition to lepidic growth, the possibility of the presence of micro-, for example, pseudo papilla which are not found in alveolar adenomas according to the literature, as well as our findings.…”

“…29 TTF-1 is the most commonly used marker for confirming that the epithelial layer is derived from type II pneumocytes. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] Keratins are also used very often to confirm the origin of epithelial components, but in some studies, keratins were negative. 9 Sak et al 8 used a broad spectrum of different keratins and all of them were positive in tumor epithelial cells (pankeratin, KRT7, KRT18, KRT19, and KRT20).…”