Blood smear of a patient with hemoglobin Southampton (Casper)

This blood smear is from a patient who presented for a routine annual examination and was found to have mild macrocytic anemia. On the peripheral blood smear, some red blood cells (RBCs) showed pleomorphic ring-like forms with purple dots, resembling a parasitic infection by Babesia or Plasmodium species (refer to inset).

She reported a diagnosis of Hemoglobin Southampton (Casper) at 1 year of age and had undergone splenectomy. Hemoglobin Southhampton is a rare unstable hemoglobin variant that causes altered hemoglobin structure and hemolysis, with macrocytosis in some individuals. Other common features include hepatosplenomegaly and methemoglobinemia.