Ultrasound diagnosis of cystic cystitis with von Brunn's nest in two cats.

Case series summary: Two cats were initially evaluated for recurrent dysuria and haematuria, which were unresponsive to antibiotic and anti-inflammatory treatments. An abdominal ultrasound revealed focal wall thickening with a severe hypoechoic multicystic parietal lesion at the bladder apex. Surgical excision of the lesion (apical cystectomy) led to complete resolution of the clinical signs in both cases. The histological findings were consistent with large cystic von Brunn's nest hyperplasia, along with foci of small glandular metaplasia. Urine and tissue cultures were negative. Cystitis cystica was diagnosed. No recurrence was reported within 2 years of surgery in both cases. Relevance and novel information: This case series illustrates the occurrence and ultrasonographic features of a type of cystitis rarely described in animals: cystic cystitis with von Brunn's nest hyperplasia. These lesions result from chronic irritation and can lead to recurrent cystitis if not excised. Cystic cystitis has previously been described histologically in cats. To the authors' knowledge, this is the first report of macroscopic apical cystic cystitis with pre-treatment ultrasound diagnosis. Surgical resection of the hyperplastic von Brunn's nests appeared to be curative in both cases.