Introduction: Ectopic ACTH syndrome is usually caused by pulmonary and bronchial tumors and rarely by pheochromocytoma. To date, most ACTH secreting pheochromocytomas reported are unilateral except two. Presented here is a third bilateral ACTH-secreting pheochromocytoma.
Patients and Methods: A 54-year-old male presented with hypertension and bilateral adrenal tumors. He denied having classic cushingoid features, or paroxysmal attacks of headache, palpitation and sweating. He was diagnosed with bilateral ectopic ACTH-secreting pheochromocytomas on the basis of biochemical and imaging findings. Then the tumors were removed, and pathologically diagnosed as pheochromocytomas. whole-exome of genomic DNA was sequenced, and secretion of ACTH and catecholamine were observed both in vivo and in vitro.
Results: Whole-exome sequencing showed that the 19 pheochromocytoma-related genes were all normal. The pheochromocytomas on both sides were all negatively stained for ACTH. But the ACTH concentration in the tumor tissue homogenates was much higher than that in other three pheochromocytomas without ACTH secretion. Electron microscopy identified two kinds of neuroendocrine cells in the tumor tissue. In primary culture of the pheochromocytoma cells，ACTH secretion was inhibited by mTOR inhibitor, AZD8055.
Conclusion: We reported a third bilateral ectopic ACTH-secreting pheochromocytoma. mTOR inhibitor could inhibited ACTH secretion in vitro.