Pheochromocytomas occur in the adrenal medulla and present with various symptoms associated with excessive catecholamine production. Although pheochromocytomas associated with ectopic ACTH-producing tumors and hyper-interleukin-6emia (hyper-IL-6emia) have been reported, those associated with both diseases simultaneously have not been reported. In pheochromocytomas with ectopic ACTH-producing tumors and hyper-IL-6emia, the disease characteristics and relationship between each hormone and cytokine are unknown. Herein, we report a case of a 56-year-old woman with stroke whose computed tomography scans of the abdomen revealed a right adrenal tumor on systemic examination. Endocrinological examination revealed elevated plasma levels of catecholamines and their metabolites in the urine and elevated levels of plasma ACTH, serum cortisol, and serum dehydroepiandrosterone sulfate, leading to a diagnosis of right pheochromocytoma and associated ectopic ACTH-producing tumor. Furthermore, hyper-IL-6emia was detected as a key indicator of anemia due to inflammatory hematopoietic disorders. The patient's general condition improved with drug therapy, including 1,000 mg/d of metyrapone, 2 mg/h of phentolamine, 8 mg/d of doxazosin, and systemic management. Dexamethasone suppression tests demonstrated suppressed serum cortisol and IL-6 levels, and dexamethasone dose-dependently increased plasma adrenaline and noradrenaline levels. These findings indicate that excess glucocorticoids play a stimulatory role in catecholamine secretion and a concentration-suppressive role in serum IL-6 levels in pheochromocytomas associated with ectopic ACTH-producing tumors and hyper-IL-6emia. The presence of rare comorbidities should be considered if the clinical findings cannot be explained by the pathophysiology of a pheochromocytoma alone because pheochromocytomas can be associated with the production of other hormones and cytokines.