title: Papillary adenoma of type II pneumocytes might have malignant potential.
abstract: Papillary adenoma of type II pneumocytes is a rare tumour. It is considered to be a benign neoplasm and is derived from immature cells in the bronchioloalveolar epithelium, however, its biological nature has not been elucidated. We report a case of an adenomatous tumour; a papillary adenoma of type II pneumocytes, which we regard as possessing malignant potential. Light microscopically, as well circumscribed, papillary tumour of predominantly cuboidal cells resembling type II pneumocytes was found, but Clara type and ciliated cells were also present. Immunohistochemically, the tumour cells reacted positively with antibodies to surfactant apoproteins (A, B), carcinoembryonic antigen, cytochrome P-450 1A1-2 and 2B1-2. Ultrastructurally, many osmiophilic lamellar bodies and electron-dense granules were demonstrated. Semi-serial sections revealed signs of transbronchial dissemination and vascular invasion. Morphometry using 12-dimensional cluster analysis disclosed features of the tumour cells which resembled those of pneumocyte type II adenocarcinoma. These findings suggest that the present case has some malignant characteristics and originates from immature bronchiolar or alveolar cells, with a potential to develop into both type II pneumocyte and Clara cell type adenocarcinomas.
authors.affiliation: Department of Pathology, Tohoku University, Sendai, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Mori
authors.forename: R
authors.initials: R
authors.lastname: Chiba
authors.forename: F
authors.initials: F
authors.lastname: Tezuka
authors.forename: M
authors.initials: M
authors.lastname: Kaji
authors.forename: T
authors.initials: T
authors.lastname: Kobubo
authors.forename: T
authors.initials: T
authors.lastname: Nukiwa
authors.forename: T
authors.initials: T
authors.lastname: Takahashi
mesh_terms: D000236:Adenoma / Q000737:chemistry / Q000473:pathology*; D000328:Adult; D001059:Apoproteins / Q000032:analysis; D001189:Aryl Hydrocarbon Hydroxylases; D002272:Carcinoembryonic Antigen / Q000032:analysis; D003577:Cytochrome P-450 Enzyme System / Q000032:analysis; D006801:Humans; D007150:Immunohistochemistry; D008175:Lung Neoplasms / Q000737:chemistry / Q000473:pathology*; D008297:Male; D008854:Microscopy, Electron; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants / Q000032:analysis; D013250:Steroid Hydroxylases / Q000032:analysis
chemical_list: D001059:Apoproteins; D002272:Carcinoembryonic Antigen; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants; C046616:pulmonary surfactant apoprotein; D003577:Cytochrome P-450 Enzyme System; D013250:Steroid Hydroxylases; D001189:Aryl Hydrocarbon Hydroxylases; C025619:steroid 16-beta-hydroxylase