Nephroblastoma Associated with Chronic Ulcerative Cystitis in a Bitch

Abstract

Background: Nephroblastoma, a rare neoplasm of embryonic origin, is primarily reported in animals aged <2 years. This neoformation clinically manifests as hematuria, polyuria and a palpable abdominal mass, and surgical removal is recommended. This report describes a case of a bitch with a neoplasm in the right kidney and ureter. Nephrectomy associated with partial cystectomy was performed; however, after 2 days she presented with uroperitoneum. The emergency surgery revealed a left ureteral rupture secondary to obstruction of the left ureteral ostium as a result of bullous edema of the urinary vesicle mucosa. The clinical-surgical approaches were efficient, leading to a survival of 27 months. 

Case: A 7-year-old bitch American Pit bull Terrier who was examined in April 2021 with pelvic limb lameness for approximately 2 years, showing reluctance to move, was diagnosed with chronic rupture of the bilateral cranial cruciate ligament. Bilateral TPLO surgery improved her mobility. However, in September of the same year, she presented dysuria for 2 weeks followed by hematuria and was diagnosed with a right renal neoplasm on abdominal ultrasound with concurrent ipsilateral ureteral obstruction, characterized by a neoformation extending through the urinary vesicle. She underwent nephrectomy combined with partial cystectomy for removing the neoplasm, which was macroscopically present up to the right ureteral ostium. After 2 days, she presented with abdominal effusion (uroperitoneum) and underwent emergency surgery, which revealed a left ureteral rupture secondary to obstruction of the left ureteral ostium as a result of bullous edema of the urinary vesicle mucosa, without suture dehiscence associated with the partial cystectomy. Total cystectomy associated with left ureterostomy was performed. No adjuvant treatment such as chemotherapy or radiotherapy was performed, and the patient had a survival time of 27 months. The histopathological findings were compatible with nephroblastoma in the right kidney and chronic-ulcerative, hemorrhagic, and edematous cystitis. 

Discussion: This case underscores the complexity of diagnosing and treating nephroblastoma in dogs. Although the tumor is more common in young animals, it can also occur in adults, as observed in this patient. Initial suspicion is difficult due to the nonspecific clinical signs, such as lethargy, hematuria and weight loss. Ultrasound was indispensable for identifying the renal mass and bladder alterations. The combination of nephrectomy and partial cystectomy was effective, although 2 days later the patient developed uroperitoneum. While this is a recognized complication in cases of urinary vesicle suture dehiscence, in this case it resulted from rupture of the left ureter. Reintervention was necessary, and preservation of the urinary vesicle was deemed unfeasible. A total cystectomy with ureterostomy to the abdominal wall was performed. It was not possible to determine whether the chronic ulcerative cystitis was associated with reduced mobility due to joint disease or represented a concurrent condition with the renal neoplasm, although such an association is uncommon. Histopathological examination confirmed the diagnoses of nephroblastoma and chronic-ulcerative cystitis. No metastatic lesions were found in other organs. Even without adjuvant chemotherapy, the patient showed good progress, with a 27-month survival, which emphasizes the importance of local control and individualized assessment.

Keywords: canine, neoplasm, surgery, effusion, cystectomy, ureterostomy.

Título: Nefroblastoma associado à cistite crônica ulcerativa em uma cadela

Descritores: canino, neoplasia, cirurgia, efusão, cistectomia, ureterostomia.