Atypical feline sporotrichosis resembling vaccine-induced sarcoma: clinical and histopathological aspects

Abstract

A 7-year-old Siamese cat presenting with three ulcerated cutaneous nodules in the lumbosacral region was seen at the Laboratory for Clinical Research on Dermatozoonoses in Domestic Animals in Rio de Janeiro, Brazil. Histopathological analysis showed that the lesions consisted of polyhedral and spindle-shaped voluminous mononuclear cells with loose chromatin and clearly visible nucleoli, few giant cells, and foci of coagulative and caseous necrosis -- findings suggestive of a vaccine-induced sarcoma. No significant mitotic rate, cytological atypias or asteroid bodies were observed. Special histopathological staining with periodic acid-Schiff and Grocott's silver stain demonstrated the presence of small yeast cells characterized by simple and narrow-base budding compatible with Sporothrix schenckii. Mycological culture grew S schenckii. Cytopathology was negative for yeast cells. These atypical clinical and histopathological signs support the importance of histopathological analysis with special staining techniques, in addition to mycological culture in the diagnosis of feline sporotrichosis.

Clinical manifestation of an amelanotic Sporothrix schenckii complex isolate in a cat in Germany

“…Clinical symptoms of feline sporotrichosis can vary and include cutaneous, lymphocutaneous and systemic forms (Schubach et al, 2004). Cutaneous lesions in particular are described as multiple, often-ulcerating nodules and are associated with a high fungal load (dos Santos et al, 2013;Miranda et al, 2013). Assuming a cutaneous form of feline sporotrichosis in this case, inoculation of conidia after a trauma of the skin seems to be rational.…”