We report three cases of
Cushing's syndrome (CS) with bilateral adrenal
tumors. When bilateral adrenal
tumors are encountered, a differential diagnosis is difficult to make, especially in the case of functioning bilateral
adrenocortical adenoma. Adrenal scintigraphy has become a standard technique to determine the laterality of excessive
hormone secretion; however, this examination results in bilateral adrenal activity in the functioning bilateral
adrenocortical adenoma. Our three patients were diagnosed with
adrenocorticotropic hormone (
ACTH)-independent CS based on biochemical testing, and an abdominal computed tomography (CT) scan detected bilateral adrenal
tumors. Adrenal scintigraphy showed bilateral adrenal activity in all cases. However, adrenal venous sampling (AVS) demonstrated three different
hormone-excess patterns (case 1: bilateral
cortisol-excess secretions; case 2: unilateral
cortisol-excess secretion and bilateral
aldosterone-excess secretions; and case 3: bilateral
cortisol-excess secretions and bilateral
aldosterone-excess secretions). Based on these findings, we could select optimal treatment for each case. Therefore, AVS is useful to obtain a definitive diagnosis and adequate
therapy for CS with bilateral adrenal
tumors.