We report the case of a 76 ys-old woman with overactive bladder syndrome, determined by an histological exam of interstitial cystitis with plasma cell infiltration. To the best of our knowledge, in literature only a similar case has been described. The patient has been treated with corticosteroid therapy allowing a transitory benefit; despite this fact, after side effects have been shown, this therapy has been interrupted leading to the worsening of the previous sintomatology. Therefore the patient has undergone to radical cystectomy with orthotopic ileal neobladder. The phlogistic infiltration of the bladder wall is represented by the plasma cells for over 90% of the whole population. In addition, blood specimen was positive for perinuclear antineutrophil cytoplasmic antibodies (p-ANCA). All these elements could hint at a chronic cystitis due to autoimmune aetiology.