Hyperpigmentation
Hyperpigmentation can be a sign of ACTH-independent (primary) adrenal insufficiency. High levels of ACTH found in these patients stimulate the melanocortin-1 receptor in the skin, resulting in hyperpigmentation. It tends to first occur in areas of the skin under pressure, including elbows, knuckles, palmar creases, lips, and buccal mucosa.
Patient 1:
This is a previously healthy middle-aged man who presented with severe abdominal pain, hypotension, and colitis on cross-sectional imaging. He described many years of skin darkening, fatigue, and abdominal pain. After the history and examination, the patient was suspected to have adrenal crisis, which was confirmed with biochemical testing. Prior to this presentation, the patient had seen several doctors over the years, including a dermatologist, but he remained undiagnosed.
Patient 2:
This is a previously healthy young woman who was diagnosed with primary adrenal insufficiency. Hyperpigmentation can be seen over the knuckles. The astute observer will also note that the patient has about 3 mm of fingernail growth since she last painted her nails. Fingernails grow at rate of approximately 1 mm per week, and so the illness was predicted to have began approximately 3 weeks prior to presentation, which was corroborated by the patient.
