Abstract
Ectopic adrenocorticotropic hormone (ACTH) syndrome is usually caused by pulmonary and bronchial tumors and rarely by pheochromocytoma. To date, the majority of ACTH-secreting pheochromocytomas have been unilateral, with the exception of two cases. A 54-year-old male presented with hypertension and bilateral adrenal tumors. The patient did not report having classic cushingoid features or experience of paroxysmal headaches or sweating, but presented with a slight abdominal obesity. The patient was clinically and pathologically diagnosed with bilateral ectopic ACTH-secreting pheochromocytomas. Whole-exome sequencing demonstrated that the 19 pheochromocytoma-related genes were unmutated. The pheochromocytomas on the two sides exhibited negative ACTH staining, but the ACTH concentration was markedly higher in the tumor tissue homogenates than in those tumors of another 3 patients with non-ACTH secretion pheochromocytoma. Electron microscopy identified two types of neuroendocrine cells in the tumor tissues. Primary culture of the pheochromocytoma cells revealed that ACTH secretion was inhibited by a mechanistic target of rapamycin inhibitor, AZD8055.