Neuroendocrine cell hyperplasia in colonic tissue used for long term augmentation cystoplasty

A case is described of neuroendocrine cell hyperplasia in intravesical colonic mucosa, implanted previously during augmentation cystoplasty. The patient was a 28 year old man born with posterior urethral valves, a non-functioning right kidney, and a poorly functioning dilated left kidney. The hyperplasia consisted of pure neuroendocrine acini and tubules within the lamina propria, separate from the normal intestinal glands. Adjacent intraepithelial colonic neuroendocrine cells were increased diffusely. Rectal biopsy and previous biopsies of intravesical colonic tissue contained normal neuroendocrine cell populations. Implantation of gut segments into the urinary tract predisposes to late neoplasia, but there is only one report of carcinoid tumour in uroenteric tissue. Intestinal neuroendocrine cell hyperplasia usually occurs diffusely rather than as aggregates, except when associated with adjacent carcinoid tumour. Both diffuse and nodular hyperplasia were present in this case, with an unusual and striking morphology. This is the first report of neuroendocrine cell hyperplasia in gastrointestinal tissue implanted into the urinary tract; this raises the possibility of a risk of late carcinoid tumour in uroenteric segments.