Best Answer: The spleen is in your body as a filter and it becomes enlarged when there has been a problem like an infection or disease process going on, for instance, a respiratory infection.eport Abuse. An enlarged spleen or splenomegaly is common in many blood disorders. The most common would be different types of haemolytic anaemia, where something is causing the red blood cells to rupture & these pieces get trapped in the spleen as it 'cleans' the blood.