Discussion
Diagnosis With Brief Discussion
- Diagnosis
- Atypical Adenomatous Hyperplasia
- Radiologic Findings
- Focal area of ground glass attenuation on LUL, which shows no remarkable interval size or configuration changes on 2 months follow-up CT scan.


- Brief Review
- Atypical Adenomatous Hyperplasia (AAH) of the human lung has been recently implicated as a possible precursor lesion of bronchioloalveolar carcinoma (BAC). The atypical adenomatous hyperplasia-adenocarcinoma sequence has been likened to the adenoma-carcinoma sequence in the large intestine. AAH is proliferative lesion of atypical epithelial cell along the alveolar septa & is commonly multifocal, and may explain multicentricity that is observed with some adenocarcinomas. AAH is the earliest lesion in stepwise development of BAC. AAH has been shown to have immunohistochemical, morphometric, flow cytometric and genetic abnormalities overlapping with adenocarcinoma. Certain population of AAH cells exhibits active proliferation, aneuploidy, 3p & 9p deletions & disruption of cell cycle control but p53 gene aberration or telomerase activation is absent or rare, if any.
AAH is usually discovered incidentally at microscopic exam of surgically resected specimen.
On CT scan, AAH shows small pulmonary nodule with ground-glass attenuation (GGA) which may be due to partial reduction of alveolar air-space owing to increase in cellular component within the lesion.
- References
- 1. Kitamura H, Kameda Y, Nakamura N, et al. Atypical adenomatous hyperplasia and bronchoalveolar lung carcinoma. Am J Surg Pathol 1996;20:553-562
2. Mori M, Tezuka F, Chiba R, et al. Atypical adenomatous hyperplasia and adenocarcinoma. Cancer 1996;77:665-674
3. Mori M, Kaji M, Tezuka F, Takahashi T. Comparative ultrastrutural study of atypical adenomatous hyperplasia and adenocarcinoma of the human lung. Ultrastructural pathology 1998;22:459-466
4. Suzuki K, Nagai K, Yoshida J, et al. The prognosis of resected lung carcinoma associated with atypical adenomatous hyperplasia. A comparison of the prognosis of the well-differentiated adenocarcinoma associated with atypical adenomatous hyperplasia and intrapulmonary metastasis. Cancer 1997;79:1521-1526
5. Kitamura H, Kameda Y, Ito T, Hayashi H. Atypical adenomatous hyperplasia of the lung. Implication for the pathogenesis of peripheral lung adenocarcinoma. Am J Clin Pathol 1999;111:610-622
6. Kushihashi T, Munechika H, Kyouschichi R, et al. Bronchioloalveolar adenoma of the lung: CT-pathologic correlation. Radiology 1994;193:789-793
- Keywords
- Lung, Benign tumor,