Ultrasonographic features of a urinary bladder leiomyoma in a cat.

Case summary: Leiomyoma of the urinary bladder in cats is infrequently documented in the literature, and a description of the ultrasonographic appearance has never been reported. A 9-year-old female spayed cat presented with a 6-month history of intermittent hematuria and progressive pollakiuria. On abdominal ultrasound, a large ovoid mass of mixed echogenicity was seen originating from the ventral apical bladder wall. The mass had faint peripheral hyperechoic radiating striations and was mildly vascularized, especially at its 1.5 cm point of origin from the wall. A partial cystectomy was performed to remove the mass that filled the bladder lumen. Microscopically, the well-demarcated mass extended from the inner muscular layer of the wall into the submucosal layer and was diagnosed as a leiomyoma. Surgical excision was curative.

Relevance and novel information: This is the first ultrasonographic description of a bladder leiomyoma in a feline patient. Smooth muscle tumors should be included on the differential diagnosis list in future cases with similar ultrasonographic features and chronic lower urinary clinical signs.