Atypical adenomatous hyperplasia of the lung

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Atypical adenomatous hyperplasia of the lung
Diagnosis in short

Micrograph showing atypical adenomatous hyperplasia. H&E stain.

Synonyms atypical alveolar hyperplasia

LM enlarged alveolar lining cells with hobnail morphology, round or oval hyperchromatic nuclei; spaces are typically seen between the alveolar lining cells important; limited extent (must be <5 mm); +/-nuclear enlargement (mild-to-moderate), +/-multinucleation
LM DDx adenocarcinoma in situ of lung, lung adenocarcinoma, multifocal micronodular pneumocyte hyperplasia associated with tuberous sclerosis
Site lung

Prevalence relatively common
Radiology ground glass opacity (persistent)
Prognosis benign, need to exclude lung adenocarcinoma
Clin. DDx pneumonia (chronic), lung tumours
Treatment surgical excision

Atypical alveolar hyperplasia of the lung, also atypical adenomatous hyperplasia (abbreviated AAH) and atypical alveolar hyperplasia, is considered the precursor of lung adenocarcinoma. It is typically found beside lung adenocarcinoma in resection specimens.[1]




  • Enlarged alveolar lining cells with:
    • Hobnail morphology - free (luminal) surface area > attached/basal surface area.
    • Round or oval nuclei.[1]
      • Nuclear hyperchromasia.
      • +/-Nuclear enlargement (mild-to-moderate).
      • +/-Multinucleation.
  • Spaces are typically seen between the cells[1] - important.
  • Limited extent:
    • <5 mm. †






  • p53 +ve/-ve (~60% of lesions +ve).[7]
  • Ki-67 variable.
    • Up to 40% in one paper[8] - typically lower (<10%[7]).

See also


  1. 1.0 1.1 1.2 Travis, WD.; Brambilla, E.; Noguchi, M.; Nicholson, AG.; Geisinger, KR.; Yatabe, Y.; Beer, DG.; Powell, CA. et al. (Feb 2011). "International association for the study of lung cancer/american thoracic society/european respiratory society international multidisciplinary classification of lung adenocarcinoma.". J Thorac Oncol 6 (2): 244-85. doi:10.1097/JTO.0b013e318206a221. PMID 21252716.
  2. 2.0 2.1 Sakuma, Y.; Matsukuma, S.; Yoshihara, M.; Nakamura, Y.; Nakayama, H.; Kameda, Y.; Tsuchiya, E.; Miyagi, Y. (Sep 2007). "Epidermal growth factor receptor gene mutations in atypical adenomatous hyperplasias of the lung.". Mod Pathol 20 (9): 967-73. doi:10.1038/modpathol.3800929. PMID 17618248.
  3. Mori, M.; Rao, SK.; Popper, HH.; Cagle, PT.; Fraire, AE. (Feb 2001). "Atypical adenomatous hyperplasia of the lung: a probable forerunner in the development of adenocarcinoma of the lung.". Mod Pathol 14 (2): 72-84. doi:10.1038/modpathol.3880259. PMID 11235908.
  4. 4.0 4.1 Humphrey, Peter A; Dehner, Louis P; Pfeifer, John D (2008). The Washington Manual of Surgical Pathology (1st ed.). Lippincott Williams & Wilkins. pp. 114. ISBN 978-0781765275.
  5. Kobashi, Y.; Sugiu, T.; Mouri, K.; Irei, T.; Nakata, M.; Oka, M. (Jun 2008). "Multifocal micronodular pneumocyte hyperplasia associated with tuberous sclerosis: differentiation from multiple atypical adenomatous hyperplasia.". Jpn J Clin Oncol 38 (6): 451-4. doi:10.1093/jjco/hyn042. PMID 18535095.
  6. Davidson, MR.; Gazdar, AF.; Clarke, BE. (Oct 2013). "The pivotal role of pathology in the management of lung cancer.". J Thorac Dis 5 (Suppl 5): S463-S478. doi:10.3978/j.issn.2072-1439.2013.08.43. PMID 24163740.
  7. 7.0 7.1 Kerr, KM.; Carey, FA.; King, G.; Lamb, D. (Dec 1994). "Atypical alveolar hyperplasia: relationship with pulmonary adenocarcinoma, p53, and c-erbB-2 expression.". J Pathol 174 (4): 249-56. doi:10.1002/path.1711740404. PMID 7884586.
  8. Huo, Z.; Liu, HR.; Wan, JW. (May 2007). "[Atypical adenomatous hyperplasia of lung: clinicopathologic study of 8 cases and review of literature].". Zhonghua Bing Li Xue Za Zhi 36 (5): 292-6. PMID 17706134.