Leptocytosis is seen in :

Leptocytosis is the presence of unusually thin red cells. Leptocytes are seen in severe iron deficiency and thalassaemia. Target cell is a form of leptocyte in which there is central round stained area and a peripheral rim of haemoglobin. Target cells are found in iron deficiency, thalassaemia, chronic liver disease, and after splenectomy.