Gnathostomiasis: clinicopathologic study.

Gnathostomiasis is a systemic parasitic disease that is caused by the ingestion of contaminated raw fish, the intermediate host. Involvement of the skin is a common event, and when it does happen, it can produce a superficial or creeping eruption, pseudofurunculosis, and nodular migratory panniculitis. We carried out a retrospective study of 946 cases of gnathostomiasis; 66 of them had skin biopsies. The diagnosis was made based on clinical and epidemio-logic findings as well as the therapeutic response. The most common skin finding was nodular migratory panniculitis affecting the trunk. Most of the patients were males between 20 and 40 years of age. Histopathologically, we were able to see the larva and make a definitive diagnosis in 15 cases, and in 12 cases, the worm was retrieved during the surgical procedure. In remaining cases, despite of our inability to identify the larva, the histopathologic changes were quite characteristic and included: dermal and hypodermal edema with dense mixed infiltrates composed of eosinophils admixed with lymphocytes and neutrophils, eosinophilic vasculitis, flame figures, areas of necrosis, and hemorrhage. Thus, the presence of these histopathologic features in the context of a clinical picture suggestive of gnathostomiasis allows the pathologist to make the correct diagnosis.