A 72-year-old Japanese man presented with fatigue and skin pigmentation. Physical examination showed hyperpigmentation of the dorsum of his hands and fingernails (Fig. 1A) and hyperpigmentation and rigidity of the ear cartilage (Fig. 1B). While he had a low serum cortisol level in the morning (3.1 µg/dL; normal range, 6.2–19.4 µg/dL), his adrenocorticotropic hormone (ACTH) level was markedly elevated at 1160 pg/mL (normal range, 7.2-63.3 pg/mL). There was no increase in serum cortisol level (3.0 µg/dL) after a rapid ACTH stimulation test.