PURPOSE To evaluate histological changes in stenotic urethral tissue post-radiation therapy. Treatment of prostate cancer by radiation therapy carries a risk of off-target injury to the membranous urethra causing urethral stenosis. Limited characterization of post-radiation urethral stenosis exists in the literature. We hypothesize that specific histopathologic parameters distinguish this stricture etiology. METHODS Eighty-two consecutive patients with membranous urethral stenosis underwent urethroplasty between 2013 and 2018. Seventy specimens (86.4%) were available for evaluation: 51 from patients without radiation exposure and 19 from patients with history of radiation therapy for prostate cancer. All specimens were reviewed by a pathologist blinded to patient/stricture information. Histological scoring system was used for the quantification of collagen density, collagen organization, hyalinized fibrosis, vascular density, spindle-cell change, necrosis, hemorrhage, fat entrapment, vacuolation, acute and chronic inflammation, and foreign-body giant cells. Differences in histologic outcomes between groups were statistically analyzed. RESULTS Post-radiation specimens had a higher collagen density (p = 0.01), higher collagen organization (p = 0.001), increased hyalinized fibrosis (p = 0.03), fat entrapment (p = 0.005) and spindle cell change (p = 0.005) when compared to membranous specimens without prior exposure to radiation. Post-radiation specimens also had a significantly decreased vascularity compared to specimens of non-radiated etiology (p = 0.0005). Fibrous connective tissue degenerative change with vacuolation was pronounced in post-radiation specimens and seldom seen in those without radiation (p = 0.0001). CONCLUSIONS Membranous urethral stenosis following radiation demonstrates specific histologic characteristics including vascular loss and increased scarring (collagen density, organization). This histologic grading system may be used in grading severity of radiation damage, and conceivably adopted for correlation with clinical outcomes.

中文翻译：

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接受前列腺癌治疗的男性放射后尿道狭窄的组织学特征。

目的评估放射治疗后狭窄的尿道组织的组织学变化。通过放射疗法治疗前列腺癌存在脱膜损伤尿道膜膜尿道引起尿道狭窄的风险。放射后尿道狭窄的特征有限。我们假设特定的组织病理学参数区分这种狭窄的病因。方法2013年至2018年间，连续对82例膜性尿道狭窄患者进行了尿道成形术。共有70份标本（占86.4％）可供评估：51例未接受放射治疗的患者和19例有放射治疗史的前列腺癌患者。病理学家对所有标本进行了检查，不了解患者/狭窄信息。组织学评分系统用于定量胶原蛋白密度，胶原蛋白组织，透明化纤维化，血管密度，梭形细胞变化，坏死，出血，脂肪滞留，空泡化，急性和慢性炎症以及异物巨细胞。统计分析各组之间的组织学结果差异。结果放射后标本具有较高的胶原蛋白密度（p = 0.01），较高的胶原蛋白组织（p = 0.001），透明化纤维化（p = 0.03），脂肪滞留（p = 0.005）和梭形细胞变化（p = 0.005）与未事先暴露于辐射的膜状标本相比。与非放射病因标本相比，放射后标本的血管也明显减少（p = 0.0005）。放疗后纤维结缔组织发生空泡变性的变化非常明显，而未放疗的纤维结缔组织变性则很少见（p = 0.0001）。结论放射后的膜性尿道狭窄表现出特定的组织学特征，包括血管丢失和疤痕增加（胶原蛋白密度，组织）。该组织学分级系统可以用于对放射损伤的严重性进行分级，并且可以想象地用于与临床结果相关。