Knuckle Hyperpigmentation as a Preliminary Marker of Vitamin B12 Deficiency: A Case Series

This case series highlights knuckle hyperpigmentation as an early cutaneous marker of vitamin B12 deficiency, particularly in the vegetarian population in India. While vitamin B12 deficiency commonly presents with systemic manifestations such as megaloblastic anemia, pancytopenia, and neurological deficits, knuckle hyperpigmentation can serve as a preliminary dermatological sign. Recognizing this symptom can provide an important clue towards diagnosing the underlying cause of megaloblastic anemia.