Subcutaneous dirofilariasis in Collier County, Florida, USA.

A 10-year review of the surgical pathology files of the Department of Pathology at Naples Community Hospital (Naples, FL, U.S.A.) revealed 10 cases of Dirofilaria tenuis and one of Dirofilaria ursi infection. The review consisted of only those lesions for which the pathologists had recorded the presence of a worm in the lesion. Therefore, an unknown number of subcutaneous lesions without parasites were not reviewed. Nine of the 11 cases of Dirofilaria were diagnosed as Dirofilaria or Dirofilaria tenuis originally. An additional case, previously diagnosed as Dirofilaria, was found to be a sparganum larva on review. This finding indicates that, because of the unfamiliarity of pathologists with the diagnostic characteristics of these nematode parasites, infections with Dirofilaria are underdiagnosed or misdiagnosed. If pathologists were more familiar with these parasites, their prevalence and the medical cost of this zoonosis in the southeastern United States could be determined more accurately.