A 10-year review of the surgical pathology files of the Department of
Pathology at Naples Community Hospital (Naples, FL, U.S.A.) revealed 1
0 cases of Dirofilaria tenuis and one of Dirofilaria ursi infection. T
he review consisted of only those lesions for which the pathologists h
ad recorded the presence of a worm in the lesion. Therefore, an unknow
n number of subcutaneous lesions without parasites were not reviewed.
Nine of the 11 cases of Dirofilaria were diagnosed as Dirofilaria or D
irofilaria tenuis originally. An additional case, previously diagnosed
as Dirofilaria, was found to be a sparganum larva on review. This fin
ding indicates that, because of the unfamiliarity of pathologists with
the diagnostic characteristics of these nematode parasites, infection
s with Dirofilaria are underdiagnosed or misdiagnosed. If pathologists
were more familiar with these parasites, their prevalence and the med
ical cost of this zoonosis in the southeastern United States could be
determined more accurately.