Cysticercosis
(Outside the Central Nervous System)

Radiological Diagnosis

The calcified cysticercus produces single (rarely) or multiple (often several hundred) calcifications in the soft tissues, which are linear or oval in shape and usually measure 4-10 mm or more in length and 2-5 mm in width. Cysts as large as 23 mm have been reported. The calcified cysts will have their long axes in the plane of the surrounding muscle bundle. In some series, calcified larvae have been demonstrated in up to 97% of patients examined 5 or more years after infection; such a high rate of detection is not to be expected routinely. Some patients with cerebral cysticercosis will have no evidence of calcified cysts in the muscles and are unaware of their infection.

Partially calcified cysts and even noncalcified cysts have been demonstrated by soft tissue radiography. The technique is useful when there is a localized (clinical) swelling, but as a method of "search" it is unreliable and unjustified.

Cysticerci may be seen in the lungs, where they are about 3-6 mm in diameter. The outer shell is calcified, with a somewhat lighter and softer center. In the lungs, the cysts remain more nearly round compared with the oval or elongate calcified cysts in muscle. In the liver, the cysticercus is larger and has been described as the size of a cherry (1 cm in diameter). If a cyst is seen in the liver and there are other calcified cysts in the muscles or lungs, the diagnosis is reasonably reliable; but if cysts are seen in either the lung or liver solely (a rarity), they cannot be differentiated from other causes of small calcified nodules.