A Novel Multiple Endocrine Neoplasia Type 1 Gene Variant Found in Scalp Pulmonary Neuroendocrine Tumor Metastasis

Multiple endocrine neoplasia type 1 (MEN1) is a genetic disorder usually diagnosed following hyperparathyroidism or pancreatic and gastrointestinal neuroendocrine neoplasm (NEN). We report here a case of MEN1 that was diagnosed following cancer multigene panel testing of a scalp metastasis of small cell lung carcinoma (SCLC). A 45-year-old male had noticed weight loss 20 months before admission to our department. He was identified with multiple nodules in the lungs, and bronchoscopy permitted diagnosis of SCLC at another hospital. He was then relocated to our hospital, where he began receiving chemotherapy and radiation therapy. A metastatic lesion had appeared on his scalp 3 months before admission, which had been diagnosed as a neuroendocrine tumor (NET, corresponding to grade 2) based on histopathological examination. Cancer multigene panel testing was performed and a <i>MEN1</i> variant (c.266T > G; p.Leu89Arg) was discovered; the patient was then referred to our department. Germline genetic testing revealed the same, novel germline variant in <i>MEN1</i>, leading to his diagnosis of MEN1 and lung NEN metastases. In this case, the stage of NENs can vary between the primary tumor (SCLC) and its metastases (NET), potentially involving second-hit mutations or tumor suppressor genes.