Combined large cell neuroendocrine carcinoma of the lung associated with low-grade fetal adenocarcinoma without β-catenin mutation: a case report

We report a case of combined large cell neuroendocrine carcinoma of the lung associated with low-grade fetal adenocarcinoma (LFLAC) without beta-catenin mutation in exon 3. A 33-year-old man presented at the hospital with a more than 5-month history of cough with no obvious cause. Computed tomography revealed a large, solid, round mass located in the upper lobe of the right lung. Microscopic examination showed two tumor components: large cell neuroendocrine carcinoma and low-grade fetal adenocarcinoma. Immunohistochemistry of the fetal adenocarcinoma showed abnormal nuclear/cytoplasmic expression of beta-catenin, but no exon 3 mutation in beta-catenin. Our findings provide further insight into the pathologic mechanism of FLAC.