Objective: The coexistence of silent pheochromocytoma (PHEO) and subclinical Cushing’s syndrome (SCS) of the same adrenal gland has not been reported in the English literature.

Case: We describe an adult case of clinically silent PHEO combined with SCS incidentally diagnosed by abdominal ultrasonography in a 51-year-old female patient. Physical examination revealed that her blood pressure (BP) and tension Holter monitoring were normal. Computed tomography and magnetic resonance imaging showed a solid tumor (3.53.02.5 cm) in the right adrenal gland, consistent with a nonadenomatous mass. Urinary levels of catecholamines and their metabolites were elevated. SCS was suggested by the failure to obtain adequate cortisol suppression (less than 1.8 µg/dl) following dexamethasone administration in single-dose 1-mg overnight dexamethasone suppression test (DST) and low-dose 2-mg DST. Right adrenalectomy was performed for treatment purposes. The histological diagnosis of the resected tumor was typical adrenal PHEO with adrenocortical hyperplasia.

Conclusion: Pheochromocytoma combined with SCS in the same adrenal gland is a rare entity and preoperative diagnosis of these combined tumors is difficult. Its hormonal activity and imaging characteristics are frequently very similar to those of other adrenal tumors, especially pure PHEO. Therefore, careful evaluation by endocrine tests and multiple imaging procedures are needed to provide a differential diagnosis. However, definitive diagnosis is established by histological and immunohistochemical studies. To our knowledge, the present case is the first case report that describes clinically silent PHEO combined with SCS in the same adrenal gland in the English literature. We discuss this case and review the literature on this unusual entity.

Corticomedullary mixed adrenal tumor Silent pheochromocytoma Subclinical Cushing’s syndrome Incidentaloma