Polypoid eosinophilic cystitis with pseudosarcomatous proliferative tissue in a dog

Area of Science:

• Veterinary Pathology
• Canine Urology

Background:

• Urinary bladder masses in dogs can present with varied clinical signs, including hematuria.
• Accurate histopathological diagnosis is crucial for differentiating benign conditions from neoplastic processes.

Observation:

• Two small polypoid masses were identified in the urinary bladder mucosa/submucosa of a dog presenting with hematuria.
• Histological examination revealed a proliferation of spindle-shaped, round, and pleomorphic cells with atypical nuclei and eosinophil infiltration.

Findings:

• Immunohistochemical staining confirmed the presence of fibroblasts, myofibroblasts, and macrophages within the masses.
• The masses were characterized by a diverse cell population and rare mitotic figures, leading to a diagnosis of eosinophilic polypoid cystitis with pseudosarcomatous proliferative tissue.
• The low growth activity and specific cellular composition were key diagnostic factors.

Implications:

• This case highlights the importance of thorough histopathological and immunohistochemical analysis for diagnosing unusual bladder conditions in dogs.
• Understanding pseudosarcomatous changes in benign conditions like eosinophilic polypoid cystitis is vital for appropriate clinical management and prognosis.
• The findings contribute to the veterinary literature on non-neoplastic urinary bladder masses in companion animals.