Thymic carcinoid presenting as cushing's syndrome

Primary neuroendocrine tumors of the thymus (NETTs) are rare neoplasms and are biologically aggressive. These are more frequently seen in the third to fifth decade of life. Endocrinopathies such as Cushing's syndrome, acromegaly, or multiple endocrine neoplasia-1 are associated in 50% of cases. These tumors usually present with the invasion of surrounding mediastinal structures. The long-term outcome of NETT is poor due to high risk of recurrence or metastasis. Prognosis depends on the stage, invasion, resection, and possible association of endocrinopathies. We present this case of a 17-year-old male clinically diagnosed as Cushing's syndrome with hypothyroidism, without adrenal mass but with anterior mediastinal mass, and it histologically turned out to be carcinoid of the thymus. Although thymic carcinoids are known to present with Cushing's syndrome, we have not come across with its association of hypothyroidism. Total thymectomy was performed for the case. The patient is on regular follow-up for the past 3 years, he is totally asymptomatic and not on any medication.