Hunner lesion versus non-Hunner lesion interstitial cystitis/bladder pain syndrome

Background Global consensus on the standardization of terminology for interstitial cystitis/bladder pain syndrome is lacking and is in the formative stages. The Workshop on Hunner lesion versus non-Hunner lesion at the 2018 International Consultation on Interstitial Cystitis Japan discussed prevalence, performance and outcome of endoscopy, the role of histopathology, and markers. Methods A panel of experts reviewed the literature regarding Hunner lesion vs. non-Hunner lesion interstitial cystitis/bladder pain syndrome. Results The prevalence of Hunner lesion has been reported to be 5-57%. Older age and smaller anatomic bladder capacity were associated with Hunner lesions. Cystoscopy using local anesthesia is not adequate in diagnosing interstitial cystitis but is needed to rule out confusable diseases. Cystoscopy with hydrodistention and redistention of the bladder is considered standard. A Hunner lesion is visualized as a quite typical inflammatory reaction: a reddened mucosal area with small vessels radiating towards a central scar, splitting at distension, usually associated with a waterfall bleeding pattern. Biopsies from the inflamed area show inflammatory infiltrates, granulation tissue, detrusor mastocytosis, and fibrin deposits. Ablation of Hunner lesions includes transurethral resection of lesions, fulguration, laser ablation, and cortical steroid injections. Mast cell density is a somewhat controversial matter, described differently in different studies: marked increase in Hunner lesion vs. non-Hunner lesion in the majority of studies, no difference in a few. Nitric oxide appears to be a definitive marker in distinguishing Hunner lesion vs. non-Hunner lesion disease. Macrophage migration inhibitory factor is elevated in Hunner lesion patients. Increased level of urinary proinflammatory genes expression has also been found in Hunner lesion subjects. Conclusions Hunner lesion patients are clinically and pathologically distinct from non-Hunner lesion bladder pain syndrome patients.