Pappenheimer bodies are lumps of iron and can be seen as dark blue/purple inclusions. They result from ineffective erythropoiesis or iron metabolism, as in sideroblastic anemia. Morphologically, they can be distinguished from Howell-Jolly corpuscles (DNA fragments) by their number and shape. Pappenheimer corpuscles are irregular and may occur with several at a time, while Howell-Jolly corpuscles are usually round, sharply circumscribed and often occur in singular form.