Cushing's syndrome in a patient with a corticotropin-releasing hormone-producing pheochromocytoma.

OBJECTIVE: To present the first case of Cushing's syndrome attributable solely to ectopic production of corticotropin-releasing hormone by a pheochromocytoma.
METHODS: We summarize the clinical features and results of laboratory investigations in a patient with symptoms characteristic of Cushing's syndrome.
RESULTS: Although Cushing's syndrome is usually caused by ectopic production of adrenocorticotropic hormone (ACTH), our current patient had clinical and biochemical evidence of hypercortisolism in conjunction with "normal" ACTH levels and nonsuppressible serum and urinary cortisol levels on low-dose and high-dose dexamethasone suppression testing. An abdominal computed tomographic scan revealed a 7.7-cm mass in the left adrenal gland. Light microscopic examination and immunohistochemical staining showed a pheochromocytoma with mild cortical hyperplasia. Immunostaining was positive for corticotropin-releasing hormone but negative for ACTH.
CONCLUSION: To our knowledge, this is the first case of Cushing's syndrome in a patient with pheochromocytoma caused only by ectopic secretion of corticotropin-releasing hormone without accompanying secretion of ACTH.