Recurrent thymic carcinoid tumor in familial isolated primary hyperparathyroidism

Familial isolated primary hyperparathyroidism(FIPH) is associated with multiple endocrine neoplasia type 1 (MEN1) syndrome, primary hyperparathyroidism accompanied by jaw-tumor syndrome, and familial hypocalciuric hypercalcemia. FIPH may be an early stage of MEN1 or an allelic variant of MEN1. Thymic carcinoid tumor is a rare tumor in MEN1 syndrome. Here, the authors report the case of a 40-year-old man diagnosed with recurrent thymic carcinoid tumor and FIPH. Both the patient and his elder sister had been previously diagnosed to have FIPH with a novel frameshift mutation in the MEN1 gene. Initially, the patient underwent thymectomy because of an incidental finding of a mediastinal mass in his chest X-ray, and had remained asymptomatic over the following 4 years. Pancreas computed tomography conducted to evaluate MEN1 syndrome revealed anterior and middle mediastinal masses, and resultantly, massive mass excision was performed. Histological findings disclosed atypical carcinoids with infiltrative margins. In view of the thymic carcinoid tumor relapse that occurred in this patient, the authors recommend that regular pancreas and pituitary imaging studies be conducted for FIPH associated with a MEN1 gene mutation.