Intestinal metaplasia of the bladder with dysplasia: A risk factor for carcinoma?

Aims: Intestinal metaplasia (IM) of the bladder is a benign glandular proliferation, where the urothelium becomes lined by intestinal-type epithelium. There is no association between IM and an increased risk for the development of adenocarcinoma. However, in rare cases IM shows dysplasia, similar to that of the gastrointestinal tract. We evaluated the significance of urothelial IM with dysplasia. Methods and results: Consultation cases were searched for IM of the bladder with dysplasia. We identified 20 cases, including 17 males and females, aged 31-85 years (mean 60 years). Twelve (60%) patients had low-grade dysplasia and eight (40%) patients had high-grade dysplasia. Focal dysplasia was found in eight (40%) patients and non-focal dysplasia in 12 (60%) patients. IM with dysplasia was found with concurrent adenocarcinoma in eight (40%) cases. Five of these patients (63%) had disease recurrence and three (38%) patients died from their disease. IM with dysplasia was found with concurrent urothelial carcinoma in one case. Eleven patients had IM with dysplasia without evidence of malignancy. Of these, one went on to develop non-invasive, high-grade papillary urothelial carcinoma. Conclusions: Clinical follow-up is recommended in cases of IM with dysplasia, as a significant number of these cases are associated with concurrent carcinoma.