Vitamin B12 Deficiency Presenting as Pyrexia of Unknown Origin: A Case Report.

Vitamin B12 deficiency is an uncommon cause of fever. Here we describe a case of a 16- year-old male who presented with pyrexia of unknown origin from one and half month subsequently on investigation patient diagnosed to nutritional megaloblastic anemia secondary to severe vitamin B12 deficiency after exclusion of other infective, neoplastic or inflammatory causes. Megaloblastic anemia (vitamin B12, folate deficiency) is a reversible cause of pyrexia that should be considered in any patient who presents with pyrexia from long time and pancytopenia.