Reversible cutaneous hyperpigmentation often occurs in the setting of nutritional deficiencies and protein energy malnourishment, with atypical presentations arising from autoimmune disease. Here, we present a 52-year-old female with hypertension, type 1 diabetes, and Hashimoto's thyroiditis, under the diagnosis of polyglandular autoimmune syndrome type II, referred for evaluation of asymptomatic hyperpigmentation of the palms, soles, hard palate, and tongue for 6 months. The patient underwent a significant work-up, including esophagogastroduodenoscopy, which revealed hypertrophic gastropathy as well as evidence of acquired B12 deficiency secondary to pernicious anemia. The patient was initiated on B12 supplementation, with eventual resolution of mucocutaneous findings.