Mucocutaneous Hyperpigmentation as the Diagnostic Clue to Autoimmune Polyglandular Syndrome Type 2: A Case Report

Autoimmune polyglandular syndrome type 2 (APS-2) is a rare autoimmune disorder characterized by the coexistence of primary adrenal insufficiency with autoimmune thyroid disease and/or type 1 diabetes mellitus. Because its initial manifestations are often nonspecific, diagnosis may be substantially delayed until advanced disease or adrenal crisis develops. We report the case of a 28-year-old Portuguese woman living in California who presented with a nine-month history of progressive fatigue, unintentional weight loss, nausea, vomiting, abdominal pain, and a previous syncopal episode. Recognition of diffuse mucocutaneous hyperpigmentation involving the palmar creases and tongue prompted targeted endocrine investigation. Laboratory evaluation confirmed autoimmune primary adrenal insufficiency and autoimmune hypothyroidism, establishing the diagnosis of APS-2. Treatment with intravenous hydrocortisone and fluid resuscitation was followed by levothyroxine and fludrocortisone replacement, resulting in rapid clinical improvement, the normalization of biochemical abnormalities, and complete recovery. This case highlights the diagnostic value of meticulous physical examination in patients presenting with otherwise unexplained constitutional symptoms. Recognition of these characteristic physical findings may facilitate the early diagnosis of autoimmune primary adrenal insufficiency, enabling appropriate hormone replacement before progression to adrenal crisis.