{Reference Type}: Case Reports {Title}: Knuckle hyperpigmentation in a young male: A clinical sign of B12 deficiency not to be missed. {Author}: Singh H;Subramanian A;Dibhar DP;Suri V;Bhalla A; {Journal}: Trop Doct {Volume}: 54 {Issue}: 3 {Year}: 2024 Jul 29 {Factor}: 0.828 {DOI}: 10.1177/00494755241234081 {Abstract}: Vitamin B12 and folate deficiency are reversible causes of megaloblastic anemia. Strict vegetarians are at risk of megaloblastic anemia due to low cobalamin in their diet. Knuckle hyperpigmentation in patients with megaloblastic anemia is due to excess melanin synthesis in skin. Here we present a case of a young vegetarian male with megaloblastic anemia with knuckle hyperpigmentation managed successfully with intravenous followed by oral vitamin b12 and folate supplementation.