title: Encapsulated type II pneumocyte adenoma: a case report and review of the literature.
abstract: An unusual benign lung neoplasm, a papillary adenoma of type II pneumocytes, was resected from a 26-year-old man who showed no clinical symptoms. The tumor was 2.0 cm in diameter and was localized in the subpleural region of S7 of the right lung; the cut surface showed a spherical medullary mass encapsulated by a thin layer of connective tissue. Histologically, there were cuboidal to columnar epithelial cells with a little nuclear atypia showing a monotonous papillary pattern with a delicate stroma in most parts of the tumor. There was neither capsular invasion nor metastasis of tumor cells. Nuclear DNA analysis of the tumor cells showed a diploid pattern and a low S-phase fraction. The immunohistochemical study revealed that most tumor cells contained a large amount of surfactant apoprotein in the cytoplasm. Osmiophilic lamellar bodies characteristic of type II pneumocytes were frequently found by electron microscopy. These findings indicate that this was a benign adenoma of the lung arising from type II pneumocytes.
authors.affiliation: Department of Thoracic Surgery, University of Tsukuba, Ibaraki, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Yamamoto
authors.forename: H
authors.initials: H
authors.lastname: Horiguchi
authors.forename: T
authors.initials: T
authors.lastname: Shibagaki
authors.forename: H
authors.initials: H
authors.lastname: Kamma
authors.forename: T
authors.initials: T
authors.lastname: Ogata
authors.forename: K
authors.initials: K
authors.lastname: Mitsui
mesh_terms: D000236:Adenoma / Q000235:genetics / Q000473:pathology*; D000328:Adult; D004273:DNA, Neoplasm / Q000032:analysis; D005434:Flow Cytometry; D006801:Humans; D008175:Lung Neoplasms / Q000235:genetics / Q000473:pathology*; D008297:Male
chemical_list: D004273:DNA, Neoplasm