ESSIC uses the name bladder pain syndrome (BPS) instead of interstitial cystitis (IC) and/or painful bladder syndrome (PBS):
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Bellocq JP, Lassabe-Roth C, Viville C, et al. J Urol (Paris) 1982;88:255-60
the authors emphasize the difficulties of the pathological diagnosis on biopsy samples and relate the usual behaviour of carcinoma in situ who may often simulate an interstitial cystitis