[Case #4: Bronchiolar adenoma].

Bronchiolar adenoma/ciliated muconodular papillary tumour is a benign peripheral lung tumour. Histologically, it is characterized by a predominant papillary architecture and by a bilayered bronchiolar-type epithelium containing a continuous basal cell layer. This observation concerns a 72-year-old woman who underwent surgery for a bifocal adenocarcinoma. The peritumoral parenchyma contained BA/CMPT. The main differential diagnoses are discussed, including other benign or malignant lesions. The major criteria for diagnosis include location, architecture, cell population and immunohistochemistry profile on surgical specimens.