Phenotyping of interstitial cystitis/bladder pain syndrome

Interstitial cystitis/bladder pain syndrome is a chronic, potentially debilitating condition characterized by pain perceived to be related to the bladder in conjunction with lower urinary tract symptoms, and includes a wide variety of clinical phenotypes with diverse etiologies. Currently the only clinically relevant proven phenotype of interstitial cystitis/bladder pain syndrome is the Hunner lesion. Whether the presence of Hunner lesions is a hallmark of a distinct disease cohort or a potentially transient feature of non‐Hunner lesion phenotype has been debated but remains controversial. There are few documented examples of a patient converting between the two forms. Growing clinical and basic evidence supports eliminating the Hunner lesion phenotype from the bladder pain syndrome umbrella and considering it a distinct disease. The Hunner lesion phenotype is characterized by distinct bladder histology, including subepithelial chronic inflammatory changes and epithelial denudation, and specific clinical characteristics (older onset age, severe bladder‐centric symptoms, reduced bladder capacity, and favorable response to the lesion‐targeted therapies). To define the Hunner lesion phenotype, it is necessary to develop an atlas of standardized images of cystoscopic (and, if possible, pathological) appearances of Hunner lesions. A true potential and clinically relevant phenotype of interstitial cystitis/bladder pain syndrome may be patients with non‐bladder‐centric symptoms, characterized by the affect dysregulation and somatic symptoms, and a greater bladder capacity in absence of Hunner lesions. In the present workshop, we concluded that the Hunner lesion is a valid phenotype and can reasonably be considered a disease in its own right. Assessment of bladder capacity and the extent of symptoms (bladder beyond or bladder centric) may help phenotyping of interstitial cystitis/bladder pain syndrome. Proper phenotyping is essential for the diagnosis and treatment of interstitial cystitis/bladder pain syndrome, and for facilitating research.