Follicular cystitis (FC) is a rare inflammatory disorder of the bladder that primarily affects women. The precise cause of FC remains largely unclear, although it has been linked to inflammatory processes and bacterial infections, particularly following urinary tract infections. In the context of orphan diseases like follicular cystitis, where large-scale clinical trials are often unfeasible, case reports play a crucial role in guiding the scientific community toward effective treatment strategies.

We present the case of an 87-year-old female patient who arrived at the emergency department with significant hematuria that could not be managed through catheterization and continuous bladder irrigation. Consequently, she required surgical intervention in the operating room, where a transurethral resection of the bladder tumor was performed, along with the evacuation of blood clots. Histopathological analysis revealed the rare diagnosis of follicular cystitis.

As a rare inflammatory condition of the bladder, the pathophysiology of FC remains unknown. While inflammatory processes and bacterial infections are frequently mentioned, they have not been conclusively proven. We provide an overview of this unusual condition, including its histological diagnosis, differential diagnoses, and potential treatment options.

Various management strategies have been proposed for treating FC. Given the condition's rarity, large population-based studies are unlikely to yield recommendations, highlighting the importance of case reports in guiding urologists in clinical practice.