Cushing's syndrome secondary to typical pulmonary carcinoid with mutation in BCOR gene: A case report.

RATIONALE: Typical pulmonary carcinoid is a kind of low-grade malignancy neuroendocrine tumor. Cushing's syndrome is a very rare clinical feature of typical pulmonary carcinoid caused by hypercorticism. Complete tumor resection is the standard curative treatment for primary typical pulmonary carcinoid. However, our knowledge on the gene level of typical pulmonary carcinoid is limited.

PATIENT CONCERNS: A 42-year-old man was admitted to our hospital for progressive weight gain within one year. No other obvious symptoms were obsessed in this patient. He was clinical diagnosed with ectopic adrenocorticotropic hormone syndrome through hormonal tests and imaging exams. Positron emission tomography-computed tomography detected a pulmonary nodule localized in the middle lobe of the lung and it is thought to be the ectopic source.

INTERVENTION: This patient received a pulmonary wedge resection. After the surgery, a genetic sequencing was performed and it reported a mutation (S1240Cfs*21) in the BCOR gene.

DIAGNOSIS: Postoperative pathology confirmed the diagnosis of ACTH-producing typical pulmonary carcinoid.

OUTCOMES: The patient had a smooth postoperative course and no recurrence of the tumor was found for 3 years.

LESSONS: Mutation in BCOR gene is quite common in pulmonary neuroendocrine tumor and it has been proven to play a role in the development of some tumor. We herein first report BCOR gene mutation in Cushing's syndrome secondary to TPC and it may become a promising therapeutic target in the future.