Clinical implication of MEN1 mutation in surgically resected thymic carcinoid patients

Thymic carcinoid refers to a neuroendocrine tumour arising in the thymus, accounting for about 2–7% of anterior mediastinal masses (1,2). Approximately 40% of patients have Cushing syndrome as a result of adrenocorticotropic hormone secretion by the tumour (1). Since the initial report of thymic carcinoid by Rosai and Higa in 1972 (3), about 200 cases of thymic carcinoid have been reported in English literature so far. We describe a 62-year-old male patient with surgically resected thymic carcinoid and mutations of MEN1 gene were detected by next generation sequencing (NGS). Previous evidence indicates that thymic carcinoids occur in 1–5% of patients with multiple endocrine neoplasia type 1 (MEN1) syndrome and are a major cause of morbidity and mortality (4). We did a literature review and analyzed the clinicopathologic characteristics of all thymic carcinoid patients with the initial manifestation of MEN1 syndrome. All of thymic carcinoids patients with somatic mutation of MEN1 gene had MEN1 syndrome. Considering none of other organs involved and a negative family history of MEN1 syndrome, our patient could not be diagnosed with MEN1 syndrome at this moment. Based on the findings of our literature review, we proposed that somatic mutation test of MEN1 gene and evaluation of other organs are recommended for thymic carcinoid patients. Moreover, close follow-up of thymic carcinoid patients with somatic mutation of MEN1 gene is necessary and could help detect disease recurrence and metastases early