Histopathological evaluation of urethroplasty with dorsal buccal mucosa: an experimental study in rabbits

Histological Comparison of Buccal and Lingual Mucosa Grafts for Urethroplasty: Do They Share Tissue Structures and Vascular Supply?

Comparable outcomes were published using a buccal mucosa graft (BMG) from the cheek and a lingual mucosa graft (LMG) from the sublingual area, for urethral augmentation or substitution. To date, no histological comparison between both grafts has been conducted. We histologically assessed BMG and LMG harvested during urethral surgeries, aiming to compare graft properties and vascular support. We conducted a prospective single cohort study, including oral mucosa urethroplasty patients. During surgery, graft dimensions and donor sites were collected, and a 0.5 × 0.5 cm sample was obtained from the prepared graft. Formalin-fixed paraffin-embedded samples were sliced at 4 micrometres (µm) and hematoxylin-eosin stained. Using a telepathology tool, all slides were digitalized and measured from 10× to 40× magnification. In each graft, global and individual layers thicknesses were assessed, including vascular density and area. Descriptive and comparative (parametrical and non-parametrical) statistical analysis occurred. We collected 57 grafts during 33 urethroplasties, with 30 BMG and 22 LMG, finally, included. The mean age was 56.6 (SD 15.2) years, and the mean graft length was 5.8 (SD 1.7) cm and the width was 1.7 (SD 0.4) cm. The median graft thickness was 1598.9 (IQR 1200–2100) µm, the mean epithelium layer was 510.2 (SD 223.7) µm, the median submucosa was 654 (IQR 378–943) µm. the median muscular was 477.6 (IQR 286–772) µm, the median vascular area was 5% (IQR 5–10), and the median adipose tissue area was 5% (IQR 0–20). LMG were significantly longer and narrower than BMG. Total graft thickness was similar between LMG and BMG, but the epithelium and submucosa layers were significantly thinner in LMG. The muscular layer was significantly thicker in LMG. Vascular density and vascular areas were not significantly different between both types of grafts. LMG showed significantly less adipose tissue compared with BMG. Our findings show LMG and BMG for urethroplasty surgeries share the same thickness and blood supply, despite having significantly different graft sizes as well as mucosal and submucosal layers thickness.

Bracka's Method of Proximal Hypospadias Repair: Preputial Skin or Buccal Mucosa?

OBJECTIVE

To analyze treatment results of staged surgical repair of proximal forms of hypospadias according to Bracka's technique using preputial vs buccal grafts.

MATERIAL AND METHODS

We retrospectively reviewed 220 patients with proximal forms of hypospadias treated with Bracka's urethroplasty technique. They were divided into 2 groups: Group I-108 patients treated with preputial skin grafts in 2001-2013; Group II-112 patients who underwent urethroplasty with buccal mucosa grafts in 2013-2016.

RESULTS AND DISCUSSION

Of the Group I patients with preputial skin grafts, complications were obtained in 33 (31%) cases; in Group II-23 (20%) cases. Complications include fistulas, defects of urethra, and scar contraction of grafts. The cosmetic results according to Hypospadias Objective Penile Evaluation scale were more satisfactory when buccal mucosa grafts were used. Further studies are needed to analyze the long-term changes posturethroplasty with both preputial skin and buccal mucosa grafts.

CONCLUSION

This is one of the only studies to compare complications and histology of the 2 free grafts: preputial skin and buccal mucosa. This study affirms that a staged surgical method with the use of free grafts according to Bracka's technique is a successful method of treatment of proximal forms of hypospadias in children achieving good functional and cosmetic results with a relatively low rate of complications.

Histopathological changes in oral mucosa in cases of failed augmented urethroplasty

OBJECTIVE

Histopathological changes in oral (buccal or lingual) mucosa after exposure to urine are still not completely understood. We evaluated these changes in free oral mucosal graft integrated in human urethra.

MATERIAL AND METHODS

Total 19 patients with recurrent urethral stricture after oral mucosa urethroplasty (buccal 12 and lingual 7) were prospectively evaluated. Intraoperatively integrated buccal or lingual mucosal graft sample that was previously engrafted to urethra was completely excised along with healthy oral mucosa, and it was sample processed for histopathological evaluation by dedicated pathologist. Preoperative clinical data were properly collected from all the study participants.

RESULTS

The mean age of the patients was 30 years, and the mean preoperative peak flow rate was 4.2 mL/s. Etiology of initial stricture was idiopathic in 13 (68.42%) patients and traumatic urethral catheterization in 6 (31.58%) patients. Mean interval from previous buccal mucosal urethroplasty to current urethroplasty was 21.9 months (range 12-46 months). On repeat urethroplasty, the mean stricture segment length was 59.2 (38-77) mm [60.08 (38-74.6) mm buccal, and 58.32 (39.6-77) mm lingual]. These integrated oral mucosal grafts maintained their histopathological characteristics in all patients except some kind of changes like submucosal fibrosis in seven (58.33%) cases of buccal and vacuolar degeneration in five (71.42%) cases of lingual mucosal urethroplasty.

CONCLUSION

Histopathological characteristics of integrated oral (buccal and lingual) mucosal grafts were maintained even on exposure to urine except some changes like submucosal fibrosis and vacuolar degeneration. Impact of these changes require further research.

Can a graft be placed over a flap in complex hypospadias surgery? An experimental study in rabbits

Purpose:

To develop a rabbit experimental study to test the hypothesis that surgical repair of hypospadias with severe ventral curvatures might be completed in one stage, if a graft, such as buccal mucosa, could be placed over the tunica vaginalis flap used in corporoplasty for ventral lengthening, with the addition of an onlay preputial island flap to complete the urethroplasty.

Materials and methods:

The experimental procedure with rabbits included a tunica vaginalis flap for reconstruction of the corpora after corporotomy, simulating a ventral lengthening operation. A buccal mucosa graft was placed directly on top of the flap, and the urethroplasty was completed with an onlay preputial island flap. Eight rabbits were divided into 4 groups, sacrificed at 2, 4, 8 and 12 weeks postoperatively, and submitted to histological evaluation.

Results:

We observed a large number of complications, such as fistula (75%), urinary retention (50%) and stenosis (50%). There were two deaths related to the procedure. Histological evaluation demonstrated a severe and persistent inflammatory reaction. No viable tunica vaginalis or buccal mucosa was identified.

Conclusions:

In this animal model, the association of a buccal mucosa graft over the tunica vaginalis flap was not successful, and resulted in complete loss of both tissues.

Buccal mucosal graft interposition in the treatment of recurrent vesicovaginal fistula: A report on two cases

OBJECTIVE

To present the use of autologous buccal mucosa graft (BMG) in the treatment of recurrent vesicovaginal fistula (VVF).

CASE REPORTS

In 2011, two women, aged 45 years and 56 years, were admitted due to recurrent VVF. Both women had previously undergone abdominal hysterectomies for benign conditions and, subsequently, vaginal VVF repair due to vaginal urine leakage. On admission, the younger woman had a round fistula, with a diameter of 1.5 cm, located on the left side, supratrigonally; the other woman had an ellipsoidal fistula measuring 2.5 cm × 1.5 cm, located medially and supratrigonally. Both women underwent suturing of the VVF with the interposition of BMG. After the last treatment, both women were cured.

CONCLUSION

Treatment of recurrent VVF with the interposition of BMG is a good alternative to the use of other tissue grafts. Larger series are needed to confirm the advantages of this method.

Onlay foreskin flap anastomosed directly to the tunica albuginea: a short-term experimental study in rabbits

INTRODUCTION

In severe hypospadias, urethral plate division is necessary for curvature correction. To configure the new urethra, an approach has been described using a foreskin flap directly anastomosed in an 'onlay' fashion to the tunica albuginea of the corpora cavernosa. Results suggest that it is possible to use the corpus cavernosum albuginea as the posterior wall of the neourethra without the need of a dorsal graft.

OBJECTIVE

The present experimental study aimed to evaluate the histological characteristics and healing pattern of this procedure.

STUDY DESIGN

Sixteen New Zealand male rabbits were divided into two groups of eight animals. Eight animals underwent 1-cm longitudinal dorsal incision of the penile urethra and the edges were anastomosed to the tunica albuginea (Group 1). Eight other animals underwent complete excision of 1.0 cm of penile urethra. Urethroplasty was performed using a foreskin flap directly anastomosed as an onlay to the albuginea, as shown in the figure (Group 2). Sacrifice and histological assessment was performed 2, 4, 8 and 12 weeks postoperatively.

RESULTS

In Group 1, a mild inflammatory process was noted that became almost imperceptible at 12 weeks. Fibrosis was mild at all stages in this group. Over time, a regenerative epithelium covered the corpus cavernosum. Immunohistochemistry using specific CK-7 and CK-20 confirmed the presence of urothelium. No complications were microscopically detected in this group. Group 2 presented with a more intense inflammatory infiltrate, which also resolved over time. Fibrosis was slightly more intense in this group, especially in animals that had urethral strictures. Group 2 presented with three fistulas, two were associated with urethral stricture. Histological evaluation showed the presence of epithelization over the albuginea, which turned out to be similar to the normal urothelium over time and was confirmed by immunohistochemistry. Non-keratinized stratified squamous epithelium of the foreskin flap showed good integration to the urethra.

DISCUSSION

Microscopic analysis showed that inflammation, fibrosis and complications were similar to previous studies. At 12 weeks there was a well-developed epithelium similar to normal urethra, which was confirmed by immunohistochemistry; this was similar to what occurs in the TIP technique, as previously demonstrated. It was hypothesized that the epithelium regeneration developed from the urethral edges, as demonstrated in other experimental studies.

CONCLUSION

The albuginea was covered by mature urothelium after 12 weeks, which presumably grew from the urethral edges. The foreskin flap onlay that was directly anastomosed to the albuginea completely integrated and constituted the roof of the neourethra.

Histopathological characteristics of buccal mucosa transplants in humans after engraftment to the urethra: a prospective study

PURPOSE

Histopathological changes in buccal mucosa transplants after engraftment to the urethra and exposure to urine remain nebulous. We investigated histopathological changes in buccal mucosa transplants integrated into the urethra in humans.

MATERIALS AND METHODS

We prospectively evaluated 22 patients with recurrent urethral stricture after buccal mucosa urethroplasty between November 2012 and October 2013. All patients underwent repeat buccal mucosa urethroplasty performed by a single surgeon. Intraoperatively we harvested a sample of the integrated buccal mucosa transplant previously engrafted to the urethra, a sample of healthy urethra, a sample of freshly harvested buccal mucosa from the contralateral inner cheek and a sample of fibrotic tissue from the area of the current stricture. A dedicated uropathologist performed meticulous histopathological examination of all tissue samples using hematoxylin and eosin staining. Preoperative clinical data were also collected on all patients.

RESULTS

The mean interval from previous to current buccal mucosa urethroplasty was 22.2 months (range 4.1 to 76.0). Mean stricture length at repeat urethroplasty was 52.7 mm (range 30.0 to 70.0). Histopathological characteristics of the integrated buccal mucosa transplants were completely preserved in all patients, consisting of thick sheets of stratified nonkeratinized squamous epithelium with a stratum spinosum. Transplants were not partially or entirely overgrown with urothelium.

CONCLUSIONS

Buccal mucosa transplants retain their histopathological characteristics and are not overgrown with urothelium after urethral engraftment and urine exposure in humans. These findings may explain the superiority of buccal mucosa transplants on the outcome of substitution urethroplasty compared to that of other materials.

A retrospective evaluation of challenges in urethral stricture management in a tertiary care centre of a poor resource community

Background

Management of urethral stricture has evolved over the years with better understanding of the pathology, advancement in imaging, and introduction of several techniques of urethral reconstruction. In sub-Saharan Africa, advancement in management of urethral stricture may not be comparable with what obtained in most developed nations because of problems like late presentation and persistence of rare complications still reported in recent literature from the region.

Objectives

We set to evaluate the challenges faced by urologists involved in the management of urethral strictures in Osogbo, a poor resource community in south western Nigeria.

Patients and Methods

A retrospective study was performed in the urology unit of Ladoke Akintola University of Technology Teaching Hospital, Osogbo, Nigeria between July 2007 and July 2012. Information was retrieved from patients’ clinical notes and analyzed using statistical package for social sciences (SPSS) version 16.0.

Results

Eighty-four patients were treated during the period of study, their ages ranged between 19 and 89 years with the mean age of 52.3 years. The mean duration of symptoms before presentation was 3 years and 1 month. Inflammation resulting from sexually transmitted infection was the commonest etiology and more than 50% of the patients presented with complications. Sixteen patients (19.1%) received no treatment due to lack of fund. More than 90% were dependent, unemployed or underemployed. Single stage reconstruction by urethral substitution was the commonest form of repair with the restenosis rate of 4.4%.

Conclusions

Prevalent socio-cultural and economic situation in south western Nigeria have added some peculiar challenges to the management of urethral stricture in the region.

Histological and immunohistochemical changes in the rat oral mucosa used as an autologous urethral graft

PURPOSE

The purpose of this study was to determine the histological and functional (immunohistochemical) changes that take place in oral mucosa grafts implanted in the rat urethra.

METHODS

Urethroplasty was performed in 26 male Wistar rats weighing 250 g. All animals received autologous oral mucosa urethra grafting under general anesthesia. Samples were analyzed 10, 20, 30, 40, 50, 60, 90, and 120 days after surgery using light and scanning electron microscopy and immunofluorescence for the determination of the expression of epithelial markers (pancytokeratin, cytokeratin 1, 4, 13, and filaggrin).

RESULTS

Grafted oral mucosa tissues were subjected to significant histological changes from the beginning with the formation of a well-developed epithelium whose structure was comparable to the native urethra from day 60 of the surgical implant. The immunofluorescence analysis demonstrated that the cytokeratin expression profile tended to mimic the pattern of the native urethra. These data suggest that the oral mucosa is able to efficiently transdifferentiate to the urethral environment.

CONCLUSIONS

The efficient transdifferentiation process of the grafted oral mucosa at both the histological and immunofluorescence levels, and the absence of local complications confirm the clinical usefulness of this type of tissues for the repair of the urethra.

Long-term angiogenic activity of free grafts and pedicle flap in a rabbit urethroplasty model

PURPOSE

We studied the late angiogenic activity of free grafts and a pedicle flap in a rabbit urethroplasty model to determine whether angiogenic activity plays a role in late outcomes of urethral reconstruction in rabbits.

METHODS

Twenty-eight rabbits were randomly divided into five groups according to the method used to bridge a urethral defect as an onlay patch: Control, simple closure of urethral defect (Group O1); free penile skin graft (FPSG, Group A1); buccal mucosal graft (BuMG, Group B1); bladder mucosal graft (BlMG, Group C1); and pedicle penile skin flap (PPSF, Group D1). Angiogenic activity of the patch on postoperative day 84 was assessed by immunohistochemistry.

RESULTS

The angiogenic activity in Groups O1, A1, B1, C1, and D1 was 23.33 ± 4.92 (means ± SD), 42.89 ± 6.52, 55.78 ± 3.46, 53.61 ± 6.17, and 24.11 ± 9.07 vessels per optical field, respectively. There were statistically significant differences (p < .001) between Group O1 and A1 B1, C1, Group A1 and B1, C1, D1, Groups B1 and D1 and Groups C1 and D1, but not between Groups O1 and D1 (p = 1.000) and Groups B1 and C1 (p = .872). The long-term angiogenic activity of all the groups was significantly lower (p < .001) than in the corresponding early groups.

CONCLUSIONS

Although the angiogenic activity of all the groups decreased in the late assessment, the buccal mucosal graft continued to exhibit elevated angiogenesis above bladder or skin (free or pedicle) graft. Therefore, buccal mucosal patch graft might be preferable because of its easier harvesting.

Long-term results with a one-stage complex primary hypospadias repair strategy (the three-in-one technique)

PURPOSE

Complex primary hypospadias repair that warrants urethral plate division is treated mostly in two steps, not necessarily in two surgeries. Our aim was to review long-term results with a one-stage strategy based on reconstruction of the urethral plate with buccal mucosa graft and onlay transverse preputial flap anastomosis protected by a tunica vaginalis flap (the three-in-one concept).

MATERIAL AND METHODS

We were able to report on 35 patients operated for primary scrotal, penoscrotal and perineal hypospadias between March 2002 and June 2008. We reviewed all charts and had phone interviews with patients not seen for the last 24 months. We investigated parameters such as UTI occurrence, fistula, residual curvature, meatal stenosis, urethral diverticula, dehiscence, orchitis and parental perception.

RESULTS

Surgical complications occurred in 13 patients (37%): 4 meatal stenosis, 4 diverticula, 5 fistulae and 2 residual penile curvatures (total 42%). Meatal dilatation was successful in 2 cases, reflected in fistula resolution. The reoperation rate was 31.5% consisting mostly of simple procedures like fistula closure, meatotomy and penile curvature release, and complex diverticula repair in 4 cases. Parental perception was excellent for 57% (20 patients) and good or acceptable for the remaining. Mean follow-up was 4.6 years.

CONCLUSIONS

The one-step strategy is associated with 68.5% success in a single operation, whereas 31.5% will need a second repair. We recognize that meatal problems are mostly associated with fistulae and diverticula; therefore, we recommend a final acceptable proximal glandar opening that will not compromise the neourethra.

One-stage complex primary hypospadia repair combining buccal mucosa graft, preputial flap and tunical vaginalis flap (the three-in-one technique)

OBJECTIVE

Complex hypospadia repair can be performed according to different strategies, mostly in one or two stages. We present a detailed video of one patient operated according to the three-in-one technique, which combines dorsal buccal mucosa grafting for reconstruction of the incised urethral plate and a preputial flap onlay urethroplasty covered by a tunica vaginalis graft.

METHOD

After sectioning of the urethral plate to correct ventral curvature, the original plate is anchored to the proximal penile shaft. Buccal mucosa is harvested from the lower lip and sutured to the ventral penile shaft area. A transverse preputial flap is obtained and anastomosed 'onlay' to the reconstructed neouretha. The scrotal fascia is opened at the site opposite to the placement of the pedicle of the preputial flap and a careful dissection of the tunica vaginalis and cremasteric tissue is performed. This second flap is used to cover the neourethra and is fixed to the corpora by angular interrupted 6-0 PDS sutures.

RESULTS

Our series of 35 patients resulted in 68.5% success after a single operation, whereas 31.5% needed a second repair.

CONCLUSION

The technique gives excellent results and can be considered an alternative to one-stage repair in primary cases.

Critical outcome analysis of staged buccal mucosa graft urethroplasty for prior failed hypospadias repair in children

PURPOSE

Although staged buccal mucosa graft urethroplasty is a well accepted technique for salvage urethroplasty, there are few reports on this procedure for redo hypospadias repair in children.

MATERIALS AND METHODS

We reviewed patients who underwent staged buccal mucosa graft urethroplasty for redo hypospadias repair. Age, quality of graft before tubularization, meatal position, presence of balanitis xerotica obliterans and complications were recorded.

RESULTS

A total of 30 patients underwent 32 repairs during a 5-year period. Mean age at first stage was 7 years (range 1 to 17) and mean interval between stages was 9.3 months (5 to 13). Mean followup after second stage was 25 months (range 10 to 46). Meatal position before first stage was proximal in 44% of patients, mid shaft in 39% and distal in 16%. Nine patients had biopsy proved balanitis xerotica obliterans. There were no donor site complications. Four patients underwent a redo grafting procedure. Complications after second stage occurred in 11 of 32 repairs (34%), consisting of urethral stenosis in 5, glanular dehiscence in 3 and urethrocutaneous fistula in 3. A third of the patients had some degree of graft fibrosis/induration after the first stage. These patients were prone to more complications at second stage (9 of 11, 82%), compared to patients without these unfavorable findings (4 of 21, 19%; p<0.001). Presence of balanitis xerotica obliterans and meatal position were not significant factors associated with adverse outcomes.

CONCLUSIONS

Staged buccal mucosa graft urethroplasty is a suitable technique for salvage urethroplasty. Complications after second stage were seen in approximately a third of patients, mainly those with fibrotic/indurated grafts.