Insights into the Pathophysiology of Urethral Stricture Disease due to Lichen Sclerosus: Comparison of Pathological Markers in Lichen Sclerosus Induced Strictures vs Nonlichen Sclerosus Induced Strictures.

Abstract

We evaluated the pathophysiology of lichen sclerosus and nonlichen sclerosus urethral stricture disease by comparing protein expression related to inflammation, cell cycle disruption, oxidative stress, hormone receptor status and infection. Tissue samples were collected from the urethral strictures of 81 patients undergoing urethroplasty. Clinical and demographic data were obtained by chart review. After identifying areas pathognomonic for lichen sclerosus a tissue microarray was created with cores from each sample and immunohistochemistry was performed. Patients had similar baseline demographics and comorbidities. Of the 81 strictures 58 were and 23 were not due to lichen sclerosus. Lichen sclerosus strictures were significantly longer and showed higher levels of inflammation. The proportion of T cells which stained positive for CD8 was significantly higher in strictures due to lichen sclerosus (50% vs 13%, p = 0.004). CCL-4 was expressed significantly more in strictures due to lichen sclerosus (76% vs 42%, p = 0.01). Several other inflammatory markers were only found in strictures due to lichen sclerosus. Block-like p16, a surrogate for high risk human papillomavirus infection, and varicella zoster virus were found only in lichen sclerosus urethral stricture disease samples, although both were rare. Epstein-Barr virus RNA was found in significantly more lichen sclerosus samples (37% vs 10%, p = 0.024). To our knowledge this is the first study to evaluate protein expression in lichen sclerosus urethral stricture disease. These strictures demonstrate increased inflammation compared to nonlichen sclerosus urethral strictures. Markers of oxidative stress, cell cycle dysregulation and the androgen receptor do not appear to be uniquely associated with lichen sclerosus urethral stricture disease. Positive staining for several viruses in samples of lichen sclerosus urethral stricture disease suggests a possible infectious etiology.