Immunohistochemical and molecular investigation on the presence of Leishmania spp. in the skin of cats with head and neck ulcers

Background: Head and neck ulcers in cats are frequently due to allergic disorders but are also reported in feline leishmaniosis, a disease in which drugs used to treat allergy are contraindicated. Prevalence of Leishmania infection in cats from endemic regions is not negligible and parasitic DNA, but not amastigotes, was recently demonstrated in diseased and normal feline skin. Objective: The aim of this study was to investigate, through immunohistochemical and molecular techniques, the presence of Leishmania in skin of cats with head and neck ulcers. Methods: A retrospective histopathological, immunohistochemical and molecular study was conducted on paraffinembedded skin samples from 29 cats, most of them living in areas of Italy at potential risk for leishmaniosis, presenting head and neck ulcerative dermatitis. Specimens were routinely stained with haematoxylin-eosin, immunostained using a polyclonal anti-Leishmania antibody and subjected to real-time Leishmania qPCR, including an internal reference. Along with other historical and clinical data, living conditions and sampling season were recorded. Results: All specimens showed perivascular-to-interstitial, predominantly mastocytic, and to a lesser extent eosinophilicneutrophilic inflammatory infiltrate, with moderate-numerous macrophages in 19 samples. Immunostaining and PCR were all Leishmania-negative. Eighteen cats lived in Central-Southern Italy, 23 had outdoor access and 15 were sampled in Spring-Summer. Conclusion: Despite lifestyle potentially associated with infection, Leishmania was not detected in skin lesions and parasites didn’t seem to play a contributory role to head and neck ulcers in studied cats.