Análise estereológica e bioquímica do tecido conjuntivo e muscular no corpo cavernoso adjacente à placa fibrosa da doença de Peyronie

Abstract

Studies on Peyronie disease (PD) usually focus the analysis on the fibrous plaque that forms in the tunica albuginea (TA). Because this fibrotic reaction is mediated by various inflammatory soluble factors adjacent connective tissues might also be affected. This secondary effect might explain, for example, the erectile dysfunction that occurs in this disease. We thus investigated the structural organization of the connective tissue in the corpus cavernosum (CC) adjacent to the fibrous plaque using stereological and biochemical techniques:During surgery of 7 PD patients (mean age 48.3 years), biopsies were obtained from the CC adjacent to the fibrous plaque and from the plaque itself. All patients had normal erection. Controls were similarly located samples from normal penises obtained during autopsy of 5 individuals (mean age 52.3 years). Tissue samples were stained with Weigert's stain (elastic fibers), Van Gieson's stain (connective tissue), and Sirius red (collagen). Stereological analysis was done using a 42-point grid to determine volumetric densities (Vv). Total collagen content was estimated as µg hyroxyproline per mg dry CC. Vv of elastic fibers was significantly reduced by 17.3% in PD compared with controls (19.49%±3.27% vs 23.56%±1.87%; p<0.05), while SMC (34.46%±2.06%) and connective tissue (35.39%±6.15%) Vv in this disease were not significantly different from those of controls (38.38%±3.17% and 38.02%±5.03%, respectively). Vv of elastic fibers in the fibrous plaque was decreased by 38.3% compared with the normal TA (20.25%±5.49% vs 32.81%±4.75%; p<0.02), and collagen concentration in the CC from controls (77.94±24.26 µg/mg) and PD (66.57±19.39 µg/mg) did not differ significantly. Sirius red-stained sections under polarized light revealed that, in the normal CC, collagen-associated colors were homogeneously distributed. In PD, stained collagen had a disrupted orientation and had a more heterogeneous birefringence, which imply looser collagen bundles. The quantitative analyses indicated that collagen in the CC close to the fibrous plaque was not affected, although its organization was noticeably altered. Cavernosal elastic fibers were reduced though, and a similar change was found in the fibrous plaque of the TA. These results suggest that, although occurring primarily in the TA, the PD fibrous plaque may induce changes in the adjacent CC.