A large subcutaneous cyst in a Haitian man. (Pathologic Quiz Case).
Operative findings revealed a 16-cm, cystic, subcutaneous, interscapular mass that was adherent to the underlying musculature, but showed no intrathoracic or intraspinal component. Grossly, the cystic mass was multiloculated and filled with clear, straw-colored fluid. A thickened membrane with abundant loose folds and smaller adherent cystic structures was noted (Figure 1, arrow). The largest of these cystic structures measured approximately 2 cm. No organisms or foreign material were identified. The overlying skin was unremarkable.
[FIGURE 1 OMITTED]
Microscopically, a granulomatous host response with numerous foreign body-type giant cells and eosinophils was noted. The cyst revealed multiple convoluted folds and cystic spaces. A microvillous tegument was appreciated overlying a thin layer of smooth muscle and a single row of stromal cells. The stroma itself was myxomatous with numerous calciferous bodies and occasional ganglion cells in clusters (Figures 2 and 3).
[FIGURES 2-3 OMITTED]
What is your diagnosis?
The classic intestinal infection with Taenia solium results when humans ingest pork with viable cysticerci that exocyst in the small intestine. They then attach to the jejunal wall and approximately 3 months later grow into the adult tapeworm.
The aberrant life cycle occurs when humans ingest the eggs and take the role of intermediate host. Oncospheres can then hatch within the bowel and from there seed remote tissue, where they develop into cysticerci. In this case, the oncospheres were most likely directly introduced into the wound, where they excysted. Over time, the scolex degenerated and the aberrant larval form proliferated.
Proliferating acephalic larval cestode infections have been described since 1908. (1) Specific species designation has been difficult, but generally 3 distinct types can be identified. In some cases, Sparganum proliferum is favored, while in others racemose cysticercus or undifferentiated sparganum or tetrathyridium is thought to represent the aberrant cestode larva. The racemose cysticercus is generally regarded as an aberrant cysticercus of Taenia solium. (2)
Human cysticercosis is primarily a disease of underdeveloped countries. Although it has been considered rare in the United States, the neurologic manifestations have been reported to account for approximately 2% of neurologically related admissions in southern California. (3) In an autopsy series of approximately 190 000 cases, Schenone (4) reported the occurrence of neurocysticercosis in 116 otherwise asymptomatic patients.
Others have reported that in endemic areas 82% of patients with cysticercosis present with subcutaneous nodules, as present in our case. (3) Cysticercosis can develop in almost any tissue, with the clinical sequelae reflecting the affected site. (4) Diagnosis rests on histopathologic evaluation of affected tissues, particularly in subcutaneous nodules in patients from endemic areas. (5) Although not usually performed for diagnosis, culture was first accomplished in 1979. Three flattened pieces of racemose cysticercus were obtained from a neurosurgical patient. These tissues were cultured in supplemented RPMI, and after 3 months of culture were observed to be motile. A fluid-filled bladder measuring 2 cm was subsequently formed. (6)
(1.) Jung RC, Rodriguez MA, Beaver PC, Schenthal JE, Levy RW. Racemose cysticercus in human brain. Am J Trop Med Hyg. 1981;30:620-624.
(2.) Beaver PC, Rolan FA. Proliferating larval cestode in a man in Paraguay. Am J Trop Med Hyg. 1979;30:625-637.
(3.) Amatya BM, Kimula Y. Cysticercosis in Nepal. Am J Surg Pathol. 1999;23: 1276-1279.
(4.) Schenone H. Cysticercosis and hydatidosis do not always bring about detectable pathology in humans. Bol Chil Parasitol. 1989;44:63-65.
(5.) Brown ST, Brown AF, Filippa DA, Coit D, Armstrong D. Extraneural cysticercosis presenting as a tumor in a seronegative patient. Clin Infect Dis. 1992; 14:53-55.
(6.) Bruckner DA. In vitro growth of racemose cysticercosis of Taenia solium from human brain. J Parasitol. 1979;65:450.
Accepted for publication February 5, 2001.
From the Department of Pathology, Wilford Hall Medical Center/ Brooke Army Medical Center, San Antonio, Tex.
Reprints not available from the authors.
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|Author:||Baptista, Matt; Smith, Michael E.; Burton, Mark|
|Publication:||Archives of Pathology & Laboratory Medicine|
|Article Type:||Brief Article|
|Date:||Oct 1, 2001|
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