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pulmonary atypical adenomatous hyperplasia

Tuesday 12 March 2013

Also called in past: bronchioloalveolar adenoma, atypical alveolar cuboidal cell hyperplasia, atypical bronchioloalveolar hyperplasia, atypical alveolar epithelial hyperplasia, atypical alveolar cell hyperplasia, alveolar intraepithelial neoplasia, well differentiated bronchioloalveolar carcinoma of Clara cell type / type II pneumocyte type


Definition: Atypical adenomatous hjyperplasia (AAH) is defined in the WHO Histological Typing of Lung and Pleural Tumors 3rd Ed as follows,: "A focal lesion, often 5 mm or less in diameter, in which the involved alveoli and respiratory bronchioles are lined by monotonous, slightly atypical cuboidal to low columnar epithelial cells with dense nuclear chromatin, inconspicuous nucleoli and scant cytoplasm.

AAH is considered to be a precursor of pulmonary adenocarcinoma. It is usually an incidental finding in tumor resection specimens and is separate from the adenocarcinoma.

However, AAH changes may sometimes be encountered at the periphery of adenocarcinomas. In this case a tiny nodule of AAH was present at a distance from the adenocarcinoma.


- AAH at Yale Rosen Collection

- Invasive adenocarcinoma and atypical adenomatous hyperplasia at YRC

Differential diagnosis

- reactive atypical pneumocytic hyperplasia
- bronchiolization
- lepidic adenocarcinoma (ex non-mucinous bronchiolo-alveolar carcinoma )

Open references

- Atypical Adenomatous Hyperplasia of the Lung: A Probable Forerunner in the Development of Adenocarcinoma of the Lung. Masuko Mori et al. Mod Pathol 2001;14(2):72–84.

- DNA methylation changes in atypical adenomatous hyperplasia, adenocarcinoma in situ, and lung adenocarcinoma. Selamat SA, Galler JS, Joshi AD, Fyfe MN, Campan M, Siegmund KD, Kerr KM, Laird-Offringa IA. PLoS One. 2011;6(6):e21443. doi : 10.1371/journal.pone.0021443 PMID: 21731750 [Free]

- Bronchioloalveolar neoplasia. Kitamura H, Okudela K. Int J Clin Exp Pathol. 2010 Nov 12;4(1):97-9. PMID: 21228931 [Free]


- Cytogenetic findings in lung cancer that illuminate its biological history from adenomatous hyperplasia to bronchioalveolar carcinoma to adenocarcinoma: A case report. Bettio D, Cariboni U, Venci A, Valente M, Spaggiari P, Alloisio M. Exp Ther Med. 2012 Dec;4(6):1032-1034. PMID: 23226769

- DNA methylation profile during multistage progression of pulmonary adenocarcinomas. Chung JH, Lee HJ, Kim BH, Cho NY, Kang GH. Virchows Arch. 2011 Aug;459(2):201-11. doi : 10.1007/s00428-011-1079-9 PMID: 21494759