The excisional biopsy specimen of the subcutaneous nodule demonstrated granulomatous inflammation with numerous filariae that had thick cuticles with annulations (eccentric ringlike projections) and contained abundant microfilariae. The skin overlying the nodule displayed dermal microfilariae with lymphoeosinophilic infiltration.
Onchocerciasis, caused by the filarial nematode Onchocerca volvulus, is the second leading infectious cause of blindness worldwide. Nearly all of the world's estimated 18 million infected persons live in sub-Saharan Africa.1,2 Onchocerciasis is easily misdiagnosed owing to its long incubation period and its unfamiliarity to physicians working in nonendemic areas.