CASE REPORT article
Front. Oncol.
Sec. Thoracic Oncology
Volume 15 - 2025 | doi: 10.3389/fonc.2025.1617720
This article is part of the Research TopicExploring Molecular Mechanisms in Cancer through Tumor Molecular PathologyView all 6 articles
Case report: Two cases of bronchiolar adenoma/ciliated muconodular papillary tumor characterized by significant basal cell hyperplasia and squamous metaplasia
Provisionally accepted
- Department of Pathology, The 920th Hospital of Joint Logistics Support Force, Kunming, China
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Background: Bronchiolar adenoma/ciliated muconodular papillary tumor (BA/CMPT) is a rare benign pulmonary tumor from the bronchiolar epithelium. Histologically, it features a continuous basal cell layer and luminal cells. Its resemblance to invasive mucinous adenocarcinoma (IMA) and acinar adenocarcinoma complicates intraoperative frozen section diagnosis. When accompanied by extensive basal cell hyperplasia (BCH) and squamous metaplasia, it may mimic sclerosing pneumocytoma or adenosquamous carcinoma. This study presents two rare BA/CMPT cases with extensive BCH and squamous metaplasia. Case presentation: Case 1: A 62-year-old female was found to have a mixed ground-glass nodule in the right lower lung lobe on CT, raising suspicion of malignancy. She received a thoracoscopic segmentectomy. Histology revealed alveolar epithelial proliferation with extensive BCH and focal squamous metaplasia. Diagnosis: distal-type BA with BCH and squamous metaplasia. Case 2: A 67-year-old female had a solid nodule in the right lower lobe detected by CT, and a thoracoscopic wedge resection was performed. Histopathological examination revealed a lesion composed of ciliated and mucinous luminal cells overlying extensive BCH and areas of squamous metaplasia, with focal atypia observed in the basal cell layer. Diagnosis: proximal-type BA with BCH and atypical squamous metaplasia. IHC demonstrated that luminal cells in both cases expressed TTF-1, while basal cells expressed CK5/6, P63, and P40. Next-generation sequencing (NGS) did not identify any mutations or fusions in common driver oncogenes such as EGFR, BRAF, or KRAS.Postoperative follow-up showed no evidence of tumor recurrence or metastasis in either case.BA with extensive BCH and squamous metaplasia is rare and presents diagnostic challenges due to overlap with conditions such as sclerosing pneumocytoma, adenosquamous papilloma, adenosquamous carcinoma, mucoepidermoid carcinoma, and epithelial-myoepithelial carcinoma. Accurate diagnosis during intraoperative frozen section analysis is crucial for guiding appropriate surgical decision-making. IHC is essential for confirming the diagnosis.
Keywords: Lung Neoplasms, Bronchiolar adenoma, Ciliated muconodular papillary tumor, Immunohistochemistry, Basal cell hyperplasia, case report
Received: 24 Apr 2025; Accepted: 07 Jul 2025.
Copyright: © 2025 Gao, Feng, Wang, Jiang, Han and XU. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Wenmang XU, Department of Pathology, The 920th Hospital of Joint Logistics Support Force, Kunming, China
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