Introduction: According to the literature of recent years, there has been an increased interest in non-oncological diseases of the bladder, between which differential diagnostics have to be carried out in order to determine a plan for the diagnosis and treatment of patients with these nosologies. There are often certain difficulties in the differential diagnosis of some forms of viral cystitis and leukoplakia
Objective: to determine pathomorphological criteria for the differential diagnosis of leukoplakia and chronic recurrent papillomavirus cystitis.
Materials and methods: The prospective study included 85 sexually active patients aged 20–45 years, who were divided into two groups depending on the etiological factor. Patients of group I (n=70) – with chronic recurrent cystitis (CRC) of papillomavirus (PV) etiology, group II (n=15) – with leukoplakia. All patients were examined in accordance with the recommendations of the European Association of Urology (EAU) and the Russian Society of Urology (ROU); an additional endoscopic examination of the bladder (cystoscopy) was performed, followed by a morphological examination of the bladder
biopsy.
Results: A morphological examination of biopsy tissue in all patients of group I revealed koilocytic transformation of the urothelium combined with non-keratinizing metaplasia of the urothelium, and in patients of group II, in all cases, keratinizing metaplasia of the urothelium with hyperkeratosis was detected.
Conclusion: Morphological examination is the gold standard in differential leukoplakia and chronic recurrent papillomavirus cystitis

Keywords: leukoplakia, chronic recurrent cystitis, papillomavirus infection