Urethral preservation by direct anastomosis to bilateral gracilis myocutaneous flaps after distal urethrectomy for extramammary Paget disease: A case report

Abstract

A 47-year-old woman with a 6-year history of vulvar pruritus was diagnosed with vulvar extramammary Paget's disease extending to the urethra, vaginal introitus, and anal canal. Cystoscopy showed irregular mucosa limited to several millimeters from the external urethral meatus. The tumor and distal urethra were resected en bloc with a negative frozen section margin, preserving the urethral sphincter. Reconstruction used bilateral pedicled gracilis myocutaneous flaps, with the residual urethral mucosa directly anastomosed to the flap. Postoperatively, spontaneous voiding was maintained without residual urine or incontinence. At 3 years and 5 months, continence persisted without urethral stenosis or local recurrence.

Highlights

• •Extramammary Paget's disease is a malignant epithelial neoplasm.
• •Resection with urethral involvement is challenging.
• •The residual urethra was anastomosed to pedicled gracilis flaps.
• •Spontaneous voiding and continence were preserved.

1. Introduction

Extramammary Paget's disease (EMPD) is a malignant epithelial neoplasm that predominantly arises in apocrine gland-bearing regions, including the vulva and perianal areas. EMPD can spread horizontally through the epidermis beyond the clinically visible margin, producing subclinical extension.^1,2 Surgical resection remains the principal curative treatment; however, defining the resection margin can be difficult when the lesion is poorly demarcated or extends onto mucosal surfaces.¹ Urethral involvement presents the additional challenge of balancing oncologic control with the preservation of urinary continence.

We report a case of vulvar EMPD involving the distal urethra in which the patient underwent en bloc distal urethrectomy and direct anastomosis of the residual urethra to bilateral pedicled gracilis myocutaneous flaps, with preservation of spontaneous voiding and continence.

2. Case presentation

A 47-year-old woman with no relevant medical history presented to our dermatology department with vulvar pruritus for approximately 6 years. The patient repeatedly received topical treatments at other dermatology clinics because of persistent symptoms. A skin biopsy revealed intraepidermal EMPD.

To determine the extent of resection required, 50 mapping biopsies were obtained under general anesthesia from (1) the main tumor, (2) the clinically visible tumor margin, (3) sites 10 mm outside the margin, (4) the urethra, (5) the vaginal introitus, and (6) the anal canal. Paget cells were detected at sites (1), (4), (5), and (6) (Fig. 1). Cystoscopy revealed irregular mucosa extending several millimeters proximal from the external urethral meatus, with no evidence of tumor proximal to the urethral sphincter or within the bladder (Fig. 2). Urinary cytology results were negative. Imaging revealed no apparent lymph node or distant metastases. We planned to perform tumor resection with distal urethrectomy, reconstruction using bilateral gracilis myocutaneous flaps, and colostomy. Urinary diversion was reserved for intraoperative findings that precluded the preservation of an adequate urethral sphincter.

Fig. 1.

Distribution of vulvar extramammary Paget disease. The red dotted line delineates the tumor boundary determined by clinical examination and mapping biopsies. Mapping biopsies also demonstrated involvement of the urethra, vaginal introitus, and anal canal.

Fig. 2.

Cystoscopic findings in the distal urethra. The normal-appearing proximal mucosa and irregular tumor-involved distal mucosa are labeled in the image.

A multidisciplinary team comprising urologists, gastrointestinal surgeons, dermatologists, and plastic surgeons performed the surgery under general anesthesia in the lithotomy position. The skin incision followed sites confirmed to be negative on preoperative mapping biopsies, and dissection proceeded through the superficial to the middle subcutaneous fat layer. The perianal lesion was excised while preserving the external anal sphincter, and a colostomy was performed.

After cystoscopic reassessment of the proximal extent of urethral involvement, the vulvar lesion was retracted, and the periurethral tissue was dissected (Fig. 3). The urethral sphincter was preserved. Therefore, the urethra was transected approximately 1.5 cm proximal to the external urethral meatus, and intraoperative frozen section examination confirmed a negative urethral margin. The vulvar, vaginal, and perianal lesions were removed en bloc with the distal urethra.

Fig. 3.

Intraoperative dissection of the distal urethra. The vulvar lesion was retracted during periurethral dissection. The urethra and tumor-bearing tissue are labeled, and black dotted lines delineate their boundaries.

A 16 × 9-cm pedicled gracilis myocutaneous flap was designed on each medial thigh. After confirming flap perfusion, both flaps were rotated 90° to cover the extensive vulvar defect. Six 4-0 absorbable sutures were placed circumferentially at the 2-, 4-, 6-, 8-, 10-, and 12-o'clock positions on the residual urethra. After trimming the subcutaneous fat at the intended neomeatus, the urethral mucosa was passed through and directly anastomosed to a flap. The mucosal margins of the vaginal and anal canals were sutured to the flaps (Fig. 4). The total operating time was 14 h 9 min, including 1 h 29 min for the urological procedure. Blood loss was 352 g, and no transfusion was required.

Fig. 4.

Reconstruction and direct urethral anastomosis using bilateral gracilis myocutaneous flaps. (A) Before approximation of the wound edges, six 4-0 polyglactin 910 traction sutures were placed circumferentially at the 2-, 4-, 6-, 8-, 10-, and 12-o'clock positions around the residual urethra. (B) Schematic appearance after direct sutured anastomosis of the residual urethral mucosa to the reconstructed surface and closure of the surrounding skin with surgical staples. (C) Immediate postoperative appearance after completion of the reconstruction.

Histopathological examination revealed Paget cells with large round nuclei and abundant cytoplasm, predominantly within the epidermis, extending into the cutaneous adnexa and periurethral glands. A 2.3 × 1.8-mm focus of invasion was identified in the periurethral gland, leading to a final diagnosis of microinvasive primary EMPD. No lymphovascular or perineural invasion was observed. Additional frozen section analysis confirmed negative skin, urethral, vaginal, and anal margins. Immunohistochemistry revealed positive staining for alpha-methylacyl-CoA racemase, cytokeratin 7, and GATA-binding protein 3, and negativity for cytokeratin 20 and prostate-specific antigen, supporting primary cutaneous gland-derived EMPD rather than secondary involvement from a urothelial or gastrointestinal malignancy.

A flap infection developed on postoperative day 1, and wound culture yielded extended-spectrum beta-lactamase-producing Escherichia coli. Piperacillin/tazobactam and wound irrigation were administered on postoperative days 2–19, leading to resolution of the infection. The urethral catheter was removed on postoperative day 26. Uroflowmetry on postoperative day 27 showed a maximum flow rate of 24.9 mL/s, a voided volume of 175 mL, and a post-void residual volume of 0 mL. Urinary incontinence was not observed. The patient was discharged on postoperative day 44.

Approximately 5 months after surgery, lymph node metastases in the left inguinal-to-external iliac region were treated with lymph node dissection. Adjuvant therapy was not administered. At the last follow-up, 3 years and 5 months after the initial operation, no local recurrence, new lymph node metastasis after lymph node dissection, or distant metastasis was noted. The colostomy remained in place at the last follow-up. Based on the clinical interviews, spontaneous voiding and urinary continence were maintained without symptoms suggestive of urethral stenosis.

3. Discussion

EMPD may extend beyond its clinically visible boundary, and the mucosal margins of the urethra, vagina, and anal canal are particularly important for vulvar disease. Japanese guidelines suggest mapping biopsy when a curative excision is planned, although evidence defining an appropriate mucosal resection distance remains limited.¹ In this patient, extensive mapping biopsies and intraoperative cystoscopy indicated that the urethral disease was confined to the distal urethra. Frozen section assessment of the urethral margin allowed oncologically appropriate resection while preserving the sphincter.

Clinical guidelines recommend curative surgery for resectable invasive EMPD and careful follow-up for at least 5 years.² European consensus guidance similarly emphasizes that vulvar Paget's disease often extends beyond visible disease and requires continued evaluation, including biopsy of suspicious areas after treatment.³ The National Comprehensive Cancer Network guidelines categorize EMPD as a rare histologic type of vulvar cancer but do not provide a specific reconstructive strategy for urethral involvement.⁴ Therefore, reconstructive decisions should be individualized according to the extent of the disease and the amount of functional urethra and sphincter that can be preserved.

Mucosal invasion has been associated with poor long-term survival in EMPD, and oncologic control should not be compromised.⁵ Conversely, total urethrectomy with urinary diversion can substantially affect quality of life. When the disease is confined to the distal urethra, sphincter preservation may allow continence maintenance. In two reported cases with urethral involvement, advancement urethral meatoplasty using buccal mucosa after distal urethrectomy preserved urinary function without urethral stenosis or incontinence during 1–2 years of follow-up.⁶ In another case series of four patients, transurethral resection and oral mucosal grafting preserved urinary function in all patients, although two required dilation for urethral stenosis.⁷

In the present case, bilateral pedicled gracilis myocutaneous flaps simultaneously covered an extensive vulvoperineal defect and provided a well-vascularized surface for direct circumferential anastomosis of the residual urethral mucosa. This approach avoids the need for additional buccal mucosal harvesting. More than 3 years after surgery, the patient continued to void spontaneously and reported maintained continence without any symptoms of urethral stenosis. In our literature review, we found no previous reports describing direct anastomosis of the residual urethra to a gracilis myocutaneous flap after distal urethrectomy for EMPD.

In concert with our findings, a retrospective series of 230 patients suggested that function-preserving surgery may be acceptable in selected patients.⁸ The present reconstruction approach may be considered when urethral involvement is limited distally, the proximal urethral margin is histologically negative, and an adequate urethral sphincter can be preserved. Multidisciplinary assessment remains essential in these cases.

This study has several limitations. First, an early flap infection prolonged hospitalization. In addition, regional lymph node metastasis required resection approximately 5 months after the initial surgery, underscoring the need for careful nodal surveillance, even when local margins are negative and the invasion is microscopic. Finally, long-term function was assessed clinically, and repeat uroflowmetry, post-void residual measurements, and validated continence questionnaires were not obtained at the last follow-up. Therefore, functional preservation should be interpreted with caution.

4. Conclusion

After distal urethrectomy for vulvar EMPD with urethral involvement, the residual urethra was directly anastomosed to bilateral pedicled gracilis myocutaneous flaps. In carefully selected patients with distal disease, a negative urethral margin, and adequate sphincter preservation, this technique may offer a reconstructive option to avoid urinary diversion.

CRediT authorship contribution statement

Toshiki Matsushima: Investigation, Conceptualization, Data curation, Visualization, Writing – original draft, Writing – review & editing. Kensuke Mitsunari: Methodology, Conceptualization, Investigation, Project administration, Supervision, Writing – review & editing. Yuichiro Nakamura: Investigation, Writing – review & editing. Masami Ashizuka: Investigation, Writing – review & editing. Yutaka Kuwazuka: Investigation, Writing – review & editing. Ryoichi Imamura: Supervision, Writing – review & editing.

Ethics declaration

Written informed consent was obtained from the patient for the publication of this case report and any accompanying images.

This study was performed in compliance with relevant laws, regulatory frameworks and guidelines where the research took place. Ethics committee approval was not required under relevant laws and institutional guidelines. Ethics committee approval was not required because this article describes a single patient case managed in routine clinical practice. Written informed consent for publication was obtained from the patient.

This research follows the CARE guidelines and the CARE checklist.

Patient consent

Written informed consent was obtained from the patient for publication of this case report and the accompanying images.

Data availability

The data underlying this case report are not publicly available because they contain information that could compromise patient privacy. De-identified data may be available from the corresponding author upon reasonable request, subject to institutional and ethical requirements.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.