A hidden deficiency unveiled by hyperpigmentation: a case report of vitamin B12 deficiency

Vitamin B12 deficiency is a common nutritional disorder that frequently manifests with hematologic and neurologic symptoms. Dermatologic signs, such as hyperpigmentation, can occur as an early sign of deficiency but are less commonly recognized, potentially leading to delayed diagnosis. This is particularly relevant in regions with a high prevalence of nutritional deficiencies, like Nigeria. A 35-year-old Nigerian woman presented with a one-year history of progressive, non-scaly hyperpigmentation on her hands and feet, primarily affecting the palms, soles and knuckles. She had no underlying medical condition typically associated with vitamin B12 deficiency and her symptoms persisted due to misdiagnosis for presumed skin allergies by several doctors. Upon proper diagnosis, the patient received standard vitamin B12 supplementation, resulting in marked improvement in her condition. Importantly, pernicious anaemia was demonstrated as the cause of vitamin B12 deficiency, necessitating long-term treatment. This case underscores the importance of recognizing early dermatologic signs like hyperpigmentation as potential indicators of vitamin B12 deficiency. Increased awareness among healthcare providers can facilitate early diagnosis, allowing timely intervention to prevent irreversible neurological damage and ensuring potential for full recovery.