Cyclic Cushing's syndrome caused by neuroendocrine tumor: a case report.

Cushing's syndrome (CS) is a clinical syndrome characterized by hypercortisolemia. Cyclic Cushing's syndrome (CCS), which exhibits a periodic or irregular increasing pattern in cortisol, is a rare type of Cushing's syndrome. A 37-year-old man came to our hospital because of repeated dizzy spells, weakness and hypercortisolemia lasting two weeks. Endocrinological examinations indicated CCS with periodic and intermittent increases in cortisol. Enhanced computed tomography (CT) revealed space occupying lesions on the upper lobe of left lung, and biopsy eventually proved that these were pulmonary carcinoid tumors with ectopic ACTH secretion, which was subsequently manifested a Cushing's syndrome. PET-CT, ultrasound and biopsy of the thyroid gland indicated bilateral thyroid papillary carcinoma. CT scan showed bilateral nodular hyperplasia of the adrenal gland. Enhanced magnetic resonance imaging (MRI) confirmed that the high signal disappeared on the posterior lobe of the pituitary gland and that the pituitary stalk shifted left, which was suspected to be non-functional pituitary microadenoma. The patient underwent surgery involving resection of the left upper pulmonary lobe and the mediastinal lymph node around the hilus pulmonis, which resulted in complete remission of CCS. The patient then chose elective surgery for the thyroid papillary carcinoma. An analysis of the patient's genomic DNA identified a novel mutation in PDE11A: c.2032 (exon 12) G > A, which is associated with primary pigmented nodular adrenocortical disease (PPNAD). This is a novel mutation which has been no previous public clinical report on this mutation as it relates to this disease.