title: Marked subcutaneous mast cell and eosinophilic infiltration associated with the presence of multiple Dirofilaria repens microfilariae in 4 dogs.
abstract: Dirofilaria repens is a parasitic nematode in the subcutaneous tissue of carnivores, including dogs and cats, transmitted by mosquitoes. Human beings may be accidental hosts. Infection of a dog with D repens was first reported in Palestine in 1934, and 2 additional cases were reported in dogs in Israel to date. This report describes D repens infection in 4 dogs in Israel that presented with subcutaneous masses, which were cytologically characterized by marked mast cell and eosinophil infiltration. In 3 cases, multiple microfilariae were present in the lesions; rare microfilariae were present in the 4thcase. In all 4 dogs, PCR of fine-needle aspirates from the lesions were positive for D repens. The mast cells observed in all lesions were uniform and highly granulated, and with the presence of the microfilariae, a mast cell tumor was considered less likely. This report suggests that D repens infection-associated subcutaneous lesions, characterized cytologically by massive mast cell and eosinophil infiltration, should be considered a differential diagnosis for mast cell tumor, especially in geographic locations endemic for this nematode. Notably, all 4 dogs were infected with D repens despite a routine prophylactic doramectin therapy administered every 3 months, probably due to the relatively long time interval between treatments.
authors.affiliation: Koret School of Veterinary Medicine, Hebrew University of Jerusalem, Rehovot, Israel.
authors.forename: Michal
authors.initials: M
authors.lastname: Mazaki-Tovi
authors.affiliation: Ramat Hasharon Veterinary Center, Ramat Hasharon, Israel.
authors.forename: Michal
authors.initials: M
authors.lastname: Reich
authors.affiliation: Karnieli Vet Ltd., Molecular Veterinary Diagnosis, Tivon, Israel.
authors.forename: Adva
authors.initials: A
authors.lastname: Karnieli
authors.affiliation: Koret School of Veterinary Medicine, Hebrew University of Jerusalem, Rehovot, Israel.
authors.forename: Sharon
authors.initials: S
authors.lastname: Kuzi
authors.affiliation: Koret School of Veterinary Medicine, Hebrew University of Jerusalem, Rehovot, Israel.
authors.forename: Itamar
authors.initials: I
authors.lastname: Aroch
mesh_terms: D000818:Animals; D060348:Dirofilaria repens / Q000302:isolation & purification*; D004184:Dirofilariasis / Q000175:diagnosis* / Q000469:parasitology* / Q000473:pathology; D004283:Dog Diseases / Q000175:diagnosis* / Q000469:parasitology; D004285:Dogs; D004804:Eosinophils / Q000473:pathology; D005260:Female; D007249:Inflammation / Q000662:veterinary; D007557:Israel; D008297:Male; D008407:Mast Cells / Q000469:parasitology / Q000473:pathology; D008842:Microfilariae; D012876:Skin Diseases, Parasitic / Q000175:diagnosis / Q000469:parasitology / Q000662:veterinary*; D040521:Subcutaneous Tissue / Q000469:parasitology / Q000473:pathology
keywords: 
  Cutaneous dirofilariasis
  ; Canine; cytology; eosinophil; mast cell