EXPRESS: Perirenal cyst-like lesions associated with Feline Infectious Peritonitis in a Maine Coon cat

CASE SUMMARY A 7-month-old intact male Maine Coon was presented because of intermittent pyrexia, hyporexia and lethargy. On abdominal palpation, both kidneys appeared to be enlarged with an irregular shape. Hematology and serum biochemistry showed anemia, hypoalbuminemia and hyperproteinemia. Ultrasonographic findings included multiple perirenal cyst-like lesions, heterogenous cortices with cortical striation, a medullary band sign, as well as renomegaly. The cat was euthanized and a limited necropsy of the kidneys revealed pyogranulomatous lesions, which were confirmed to be related to Feline Infectious Peritonitis (FIP) by immunohistochemistry. RELEVANCE AND NOVEL INFORMATION To the authors knowledges, this is the first published report describing perirenal cyst-like lesions of the kidneys related to FIP.