Acute psychosis: a presentation of cyanocobalamin deficiency megaloblastic anemia.

Cyanocobalamin deficiency is not rare in India. Patients present with megaloblastic anemia, pancytopenia and sometimes neuropsychiatric manifestations. Subacute combined degeneration of the cord, peripheral neuropathy, dementia, psychotic depression and paranoid schizophrenia are well reported. We are reporting a case of cyanocobalamine deficiency anemia who presented with acute psychosis which readily reversed on cyanocobalamin replacement.