atypical adenomatous hyperplasia
Also found in: Acronyms.
atypical adenomatous hyperplasiaPathology lung
A term of art for what is essentially dysplassia of type-II cells in the lungs, which corresponds to a small but prominent focus of plump cells lining the air spaces. AAH is often an incidental finding in lungs resected for carcinoma, characterised by firm, 1–5-mm diameter white nodules surrounded by a polygon of interstitial fibrosis—hyperchromatic enlarged cuboidal eosinophilic pneumocytes which are neither papillary nor desquamate, sharply demarcated from surrounding lung. Some develop into bronchoalveolar carcinoma, a relatively indolent malignancy and essentially a carcinoma in situ of the lungs.
A localised proliferation of small (prostate) acini, which mimics prostate carcinoma, usually lacks cytological atypia, and has basal cells at the transition zone of the prostate. It is distinguished from well-differentiated CA by a relative lack of nuclear or nucleolar enlargement, infrequent crystalloids and a fragmented, but partially intact, basement membrane. AAH is more common in older patients with larger prostates, greater degree of nodular hyperplasia, more cancer and, if malignant, with higher Gleason scores.
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.
Atypical adenomatous hyperplasia
The over-growth of the endometrium. This precancerous condition is estimated to progress to cancer in one third of the cases.
Mentioned in: Endometrial Cancer
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.