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Imaging 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 (Figs. 7.11-7.14).

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Fig. 7.11 A-C. Cysticercosis in three patients showing typical rice grain calcifications in the soft tissues and muscles of the lower extremities. Note that the oval and linear cysticerci are aligned with their long axes in the plane of the muscle bundles of the legs. Note also the variation in size and shape of the cysticerci, although the majority are approximately 10 mm in length by 4 mm in width.

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Fig. 7.12 A, B. Cysticercosis of the muscles of the back, abdomen, buttocks, and lower extremity of another patient. Note the alignment of the calcified cysticerci in the axes of the muscle fibers and their variation in shape from elongate and linear to more plump oval or elliptical configurations. Many of the calcifications have a small lucent center and, when viewed from the side, may resemble ring calcifications.

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Fig. 7.13 A-D. Extensive cysticercosis of the soft tissues, muscles, diaphragm, and lungs in a 13-year-old Colombian woman. Note in B-D that the rice grain calcifications overlying the abdomen are actually in soft tissues and muscles of the buttocks, flanks, anterior abdominal wall, and back. In C and D calcified larvae can be seen in the diaphragm as well as in the muscles of the chest and abdominal wall, axillae, and neck. (Courtesy of Dr. William Thomas, McLean).

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Fig. 7.14 A,B. Cysticercosis involving the muscles of the neck, axillae, and chest wall (A) and the back, buttocks, abdominal wall, and thighs (B) of another patient.

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.

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