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Clinical Characteristics

The more common nonproliferative form of sparganosis is clinically the same whether caused by S. mansonoides or S. mansoni. There is usually a single discrete, tender, slowly growing subcutaneous nodule, which may migrate over a considerable distance. These nodules can persist for a long time, but patients usually request that they be excised. Spargana in the subconjunctiva cause considerable pain and irritation, edema, and excess tears. If they are in the periorbital tissues, there will be swelling and occasional proptosis which may result in blindness. Most spargana, however, are in the subcutaneous tissues or muscles of the chest and abdominal walls or limbs. Others may be in the scrotum and epididymis. Following ingestion, any of the abdominal viscera and the pleura may be affected. Peritonitis has occurred when the intestine has been perforated.

Sparganosis has caused eosinophilic cystitis with a localized mass in the bladder wall. The histopathology was similar to infections elsewhere, with a sinuous necrosis following the track of the worm. The tunnels were plugged with an amorphous necrotic eosinophilic mass; Charcot-Leyden crystals were present. On cystoscopy the bladder was hyperemic and the mass was movable. At surgery there were adhesions and necrosis between the vesicoureteric pouch and colon. Contrast urography showed the mass in the wall of the bladder, which was confirmed on CT as being 3 cm in size. The serum IgG titers and the peripheral blood eosinophilia returned to normal after surgical removal of the mass.

The route by which the sparganum reaches the CNS is unknown, but may be through the skull foramina or in the connective tissue surrounding vessels and nerves. The clinical presentation depends on the site and size of the lesion. A seizure, often without localizing neurological signs, is the most common presentation, but there may be gradual onset of hemiparesis, progressing over several years. Similarly, severe headaches may persist for years or there may be sensory changes and, in some patients, memory loss, mental deterioration, dizziness, difficulty with speech and swallowing, hemianopsia, and other CNS symptoms.

Proliferative sparganosis is rare, with probably less than 20 confirmed cases. The majority have occurred in Japan and Southeast Asia. The sparganum of S. proliferum is very invasive and spreads throughout the body by continuous branching and budding; even small pieces of tapeworm left behind after attempted excision may spread and infect distant sites. S. proliferum is most common in the CNS, but is also found in skeletal muscle and elsewhere. Because there are sometimes thousands of spargana, the clinical presentation is often of slowly growing multiple nodules, most of which are painful; there may also be a single branching lobulated mass that is highly invasive. Later in the infection, the skin and fascia over the worm become thickened, resembling elephantiasis and containing thick slimy lymph. Massive infiltration can cause disintegration and failure of the infected organs. Because the larvae can live for 10 or 20 years and the worm may continue to infiltrate tissues, death is virtually inevitable. Attempts at surgical removal of the S. proliferum are unsuccessful because of the ability of the spargana to proliferate so widely. Some unexpected clinical presentations have included pulmonary embolism and intestinal obstruction. While surgical removal of the sparganum (provided it is complete) can cure the nonproliferative form, there is as yet no way to treat proliferative sparganosis.

Sparganosis can be avoided by not eating raw fish, frogs, or snakes, by drinking only clean water, by deworming pet cats and dogs, and, of course, by choosing a poultice which does not include raw flesh.

Imaging Diagnosis

Except in the CNS, imaging shows no specific findings. Calcification has occurred in some of the spargana granulomas, and can be mistaken for cysticercosis. It is probable that the larger larvae could be recognized within a subcutaneous nodule by ultrasonography, but no reports of this have been found. An uncommon clinical presentation is eosinophilic urinary cystitis, with a localized mass (the granuloma around the worm) that can be recognized on ultrasonography, urography, or CT/MR scanning. Worm granulomas have also occurred in the testes and epididymis, presenting a difficult differential diagnosis unless movement and change in position on rescanning are recognized. Indeed, wherever the "mass" is recognized clinically or by imaging, its mobility helps to establish the diagnosis (although sparganosis is not the only parasitic infection in which the area of interest moves around). The clinical finding of raised peripheral eosinophilia and serum titers will confirm the diagnosis in these patients.

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Copyright: Palmer and Reeder

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