gms | German Medical Science

Dirofilariae are threadlike worms (nematodes) that belong to the Filarioidea family. The genus Dirofilaria consists of many species. Humans are incidental hosts for some of these, most frequently D. immitis, D. repens and D. tenuis. The natural hosts are domestic and wild carnivores, mainly dogs and cats for D. repens, dogs for D. immitis, and racoons for D. tenuis. D. immitis infection in humans usually is associated with pulmonary lesions. Subcutaneous dirofilariasis is most frequently caused by D. repens and in some cases by D. tenuis or other species. D. repens is present parts of Europe and Asia, whereas infections with D. tenuis are observed in North America.

We present two cases of subcutaneous dirofilariasis seen at the Department of Infectious Diseases and Tropical Medicine in Munich. Besides a painless subcutaneous nodule at the décolleté the patients had no other complains. Serology showed a highly positive result for filarial antibodies in one patient and negative result in the other using an Enzyme Linked Immunosorbent Assay with D. immitis antigen. Histopathological examination of the surgically excised nodules revealed the presence of Dirofilaria sp., most likely D. repens or D. tenuis. Molecular analysis of the specimens was performed at the Bernhard Nocht Institute for Tropical Medicine in Hamburg. The results of sequence analysis of mitochondrial 12S rRNA confirmed D. repens infection in both cases.

With increasing travel activity imported cases of dirofilariasis to countries without autochthonous transmission can become an important consideration in differential diagnosis in patients with subcutaneous tumors.