Lepidic predominant adenocarcinoma with aerogenous spread of mucin in a young patient — A case report

•Lepidic predominant adenocarcinoma with mucin in a young woman is rare.•We discuss the diagnosis in relation to the classification of lung adenocarcinoma.•Mucinous material filled the alveolar spaces, contributing to respiratory failure.

We present a unique case of a 26 year-old female non-smoker who expired following treatment for presumed pneumonias. At autopsy, lepidic predominant adenocarcinoma with aerogenous spread of mucin without evidence of invasion, a rare diagnosis that previously would have fallen under the umbrella of “bronchioloalveolar carcinoma,” was found. Histopathology showed mucin-secreting neoplastic cells lining the alveolar walls, as well as exfoliated and dense aggregates of mucinous debris filling the alveoli. The immediate cause of death was respiratory failure, most likely due to the significant amount of tumor-produced mucin that filled the alveolar spaces, which literally drowned the patient.