Distinct properties of pure- and mixed-type high-grade fetal lung adenocarcinomas by genetic profiling and transcription factor expression

Clinical and Pathological Characteristics and Prognosis of Lung Adenocarcinoma With High-Grade Fetal Features: A Retrospective Analysis

Fetal adenocarcinoma of the lung is a rare tumor. The clinical and pathological characteristics, treatment, and prognosis of patients with lung adenocarcinoma with fetal lung-like morphology were retrospectively investigated. The tumors of 9 patients with lung adenocarcinoma contained fetal lung-like morphology. One patient had pure-type high-grade fetal adenocarcinoma. Two patients had more than 50% high-grade fetal adenocarcinoma. Six specimens accounted for < 50% of the high-grade fetal features. It occurred in 7 men and 2 women. The median age at diagnosis was 62.0 years. Thyroid transcription factor-1 was frequently expressed in 8 specimens. All 9 specimens showed high rates of immunopositivity for β-catenin and E-cadherin. Three specimens showed nuclear β-catenin staining. Some patients showed immune expression of CDX2, α-fetoprotein (AFP), SALL4, and Glypican-3. Three of these specimens were diffusely strongly positive for p53, including 1 mixed-type high-grade fetal adenocarcinoma and 2 lung adenocarcinomas with high-grade fetal features. However, the other 6 patients had wild-type p53, including 1 pure-type high-grade fetal adenocarcinoma. PD-L1 was not expressed in all patients. Epidermal growth factor receptor mutations were detected in 1 patient. All patients were diagnosed using surgical samples. During the follow-up period of 36 months (range: 1-92 months), 3 patients received chemotherapy. One patient underwent radiotherapy. Two patients experienced recurrences. No patient died. PD-L1 expression status suggests a poor response to immune checkpoint therapy. The prognosis of the patient was relatively good.

Frequent nuclear β-catenin expression in pulmonary enteric-type adenocarcinoma according to the current World Health Organization criteria

Based on the current World Health Organization classification criteria, five of 3895 consecutive cases of surgically resected primary lung carcinomas (0.13%) categorized as enteric-type were analyzed. Three cases completely comprised tumor cells that resemble colorectal adenocarcinoma, while the other two cases exhibited features of conventional adenocarcinomas admixed with enteric components. Immunohistochemically, all patients expressed at least three of the five intestinal markers: CDX2, CK20, HNF4α, MUC2, and SATB2. None of the patients expressed TTF-1 and NKX3.1. Three cases showed nuclear accumulation of β-catenin, indicating activation of the Wnt/β-catenin signaling pathway; APC mutations were detected in one of these cases. TP53 mutations were detected in three cases. Mutated EGFR or ALK fusions were not detected. Our study demonstrates that pulmonary enteric-type adenocarcinomas share immunohistochemical features and genetic alterations with colorectal adenocarcinomas, which are characterized by frequent activation of the Wnt/β-catenin signaling pathway and a lack of actionable mutations.