Extra-pulmonary locations of the adult worms result in more severe manifestations, especially when the brain is involved. Extra-pulmonary paragonimiasis is rarely seen in humans, as the worms nearly exclusively migrate to the lungs. Despite this, cysts can develop in the brain and abdominal adhesions resulting from infection have been reported. Cysts may contain living or dead worms; a yellow-brownish thick fluid (occasionally hemorrhagic). When the worm dies or escapes, the cysts gradually shrink, leaving nodules of fibrous tissues and eggs which can calcify.