Non-parasitic splenic cysts may be epithelial (true) cysts or pseudocysts (false cysts). Epithelial (primary) Cysts of Spleen: The true splenic cysts are usually solitary and more commonly seen in children and young adults. They are often filled with serous fluid and have a heavily trabeculated inner wall. The lining epithelium is columnar, cuboidal, or squamous epithelium. Immunoreactivity for CEA and CA19.9 is seen in the epithelial cells. Most epithelial cysts of spleen are large, often symptomatic, and require splenectomy. There are rare cases of mucinous epithelial cysts with associated pseudomyxoma peritonei. Pseudocysts of Spleen: Pseudocysts make up about 75% of non-parasitic cysts of spleen. Most are solitary and asymptomatic and usually the result of trauma. By definition, they lack epithelial lining. Some of them might be true epithelial cysts in which the lining has been destroyed over time. The cyst wall is composed of fibrous tissue which may undergo calcification. They are usually filled with blood and necrotic debris.