First case of feline leishmaniosis caused by genotype E in a cat with a concurrent nasal squamous cell carcinoma

Case summary This is the first clinical report of feline viscerocutaneous leishmaniosis caused by Leishmania infantum genotype E associated with an invasive squamous cell carcinoma (SCC) in a domestic cat from Portugal. Initially, the cat presented a single cutaneous lesion in the right nostril. A fine-needle aspiration was performed and Leishmania amastigotes were observed without the presence of cells compatible with neoplasia. Systemic treatment with allopurinol was started. One year later, the cat presented a crateriform non-encapsulated and badly delineated mass in the nasal planum, with naso-oral fistulation and nasal destruction. Histologically, the skin mass consisted on an ulcerative plaque-like lesion with a nasal SCC. Leishmania infantum MON-1 parasites were detected by histopathology, culture and PCR of the skin mass, submandibular and popliteal lymph nodes, liver and spleen. Restriction enzyme analysis revealed genotype E, previously identified in humans and dogs living in the same region. Relevance and novel information This is, to the best of our knowledge, the first clinical report of feline viscerocutaneous leishmaniosis caused by L infantum genotype E. The detection and isolation of parasites from a cat that are genetically identical to the ones obtained from humans and dogs with visceral leishmaniosis highlights the need to clarify whether cats play a role in the epidemiology of this parasitic zoonosis. From a clinical point of view, this case reinforces the importance of including leishmaniosis in the differential diagnoses of feline pathology, especially in cats with cutaneous lesions.