Journal of Pathology and Translational Medicine

Case Study

Cytological features of atypical adenomatous hyperplasia and adenocarcinoma in situ of the lung: a case report: Misa Takahashi, Seiya Homma, Chisato Setoguchi, Yoko Umezawa, Atsuhiko Sakamoto; J Pathol Transl Med. 2025;59(3):195-200. Published online May 9, 2025; DOI: https://doi.org/10.4132/jptm.2025.04.09

Abstract PDF: Atypical adenomatous hyperplasia (AAH) and adenocarcinoma in situ (AIS) are generally treated as different lesions, depending on the differences in lesion size and histological findings. However, these differences are not absolute; thus, AAH and AIS are often difficult to distinguish. Moreover, whether AAH and AIS can be regarded as different lesions remains unknown because cytological specimens, especially those of AAH, are rare. In this study, we examined these uncommon cytological specimens and compared the cytological findings between AAH and AIS. We observed many common cytological features with no obvious differences between AAH and AIS. These findings suggest that these two distinct lesions can be grouped into a single category. Therefore, we propose creating a new cytological category.

Case Report

Multiple Atypical Adenomatous Hyperplasia Mimicking Lung to Lung Metastasis: A Case Report.: Sung Hwa Bae, Kyung Jae Jung, Jong Yup Bae; Korean J Pathol. 2005;39(3):203-206.

Abstract PDF: Atypical adenomatous hyperplasia (AAH) is regarded as a precancerous lesion in the multistep process for carcinogenesis of pulmonary adenocarcinoma. AAH is found in up to 25% of the lung tissue adjacent to cancer, particularly adenocarcinoma and also in 2-4% of autopsy cases. Until now, its main clinical significance is that some tumor recurrences are the lesions that have progressed from undetected AAH or they are newly developed cancers arising from AAH during the follow-up after the resection of adenocarcinoma. We present here the case of a 58-year-old woman having a large main adenocarcinoma with multiple small AAHs that mimicked lung-to-lung metastasis. AAH should be considered in the differential diagnosis of multiple small nodules during the preoperative evaluation and also during the follow-up of lung cancer patients.

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