Pseudomembranous trigonitis of the bladder: hormonal aetiology.

Fourteen formalin fixed and paraffin wax embedded biopsy specimens from 10 women (age range 34-68) presenting with pseudomembranous trigonitis were studied using a combination of anti-oestrogen receptor monoclonal antibodies in an avidin-biotin immunoperoxidase technique. All epithelial areas showing vaginal metaplasia exhibited staining confined to the nucleus in the basal and parabasal layers of the squamous epithelium while no staining was encountered in adjacent trigonal transitional epithelium included in nine of the biopsy specimens. The selective expression of nuclear oestrogen receptor in trigonal epithelium affected by vaginal metaplasia in a distribution similar to that reported in vaginal epithelium by other workers lends further support to oestrogen mediated aetiology in this condition and is consistent with an embryological derivation of the trigone, distinct from that of the rest of the bladder.