1. Raccoon Heartworm Causing a Leg Mass
- Author
-
J. Lesher, M.L. Warthan, and Molly M. Warthan
- Subjects
Pathology ,medicine.medical_specialty ,Histology ,Necrosis ,biology ,medicine.diagnostic_test ,Dermatology ,Anatomy ,biology.organism_classification ,medicine.disease ,Dirofilaria tenuis ,Pathology and Forensic Medicine ,Nematode ,medicine.anatomical_structure ,Dermis ,Subcutaneous nodule ,Dirofilariasis ,parasitic diseases ,Biopsy ,medicine ,medicine.symptom ,Dirofilaria - Abstract
A 29-year-old man from east texas presented with a 3-month history of a large, isolated, painful subcutaneous nodule on his lower right leg. An excisional biopsy showed zones of necrosis in the epidermis, dermis, and subcutaneous adipose tissue with a neutrophilic infiltrate. The dermis showed a mixed infiltrate with necrotic debris and a non-gravid adult female filarial nematode with a thick, multi-layered cuticle, paired uteri, and an intestine. The histologic features were diagnostic for dirofilaria tenuis, the raccoon heartworm. Dirofilaria tenuis causes heartworm infection in raccoons and infrequently causes human disease. When humans do contract dirofilariasis, the mode of transmission is via a bite from a mosquito infected with dirofilaria larvae. Humans are a dead end host and dirofilaria cannot reproduce in humans, but they do cause various lesions at the site of the mosquito bites. We report a very rare case of human dirofilaria tenuis infection manifesting as a subcutaneous nodule. Dirofilaria tenuis infections are very rare in the U.S., and usually occur in the Southeastern U.S.
- Published
- 2008