Perianal Endometriosis Mimicking Recurrent Perianal Abscess

Endometriosis presenting as a perianal abscess: case report

Endometriosis is common benign disorder characterized by the presence of endometrial glands and stroma outside the uterine cavity. Endometriosis of perianal region is a rare condition. We report a case of perianal endometriosis presenting initially as a perianal abscess. Transperineal ultrasound showed a 1.5 cm size irregular mixed echogenicity lesion without involving anal sphincters. Complete surgical excision was performed. The histopathological examination confirmed as endometriosis.

Perianal endometrioma presented as perianal abscess: report of two cases

Perianal endometriosis is a rare clinical presentation of the extrauterine appearance of endometrium reported in <1% of the cases. The condition is accompanied by perianal cyclic pain and a palpable mass. If diagnosed by physical examination only, the condition may be easily misinterpreted as a perianal abscess and treated improperly with incision, thus resulting in "abscess recurrence." Additional diagnostic imaging such as endoanal ultrasonography and magnetic resonance imaging should be mandatory to provide an accurate diagnosis and proper treatment resulting in low recurrence rates. We present two cases of perianal endometriomas initially diagnosed and treated as perianal abscesses.

Perianal Endometriosis: An Uncommon Site for a Common Problem

Endometriosis is the presence of uterine glands and stroma outside of the uterus. It is highly prevalent in women of reproductive age. It is usually found in the pelvis, with most cases being found on the peritoneum, ovaries, or deep in the pelvis. Extraperitoneal endometriosis is uncommon. Perianal endometriosis has an incidence of only 0.2%. We present the case of a 37-year-old woman with recurrent pain and swelling in the perineum at the site of a previous episiotomy scar. Initial imaging and assessment determined this to be scar tissue. Following re-presentation, it was mistakenly diagnosed as a perianal abscess, and the patient underwent incision and drainage. The wound failed to heal with significant induration. Further assessment of the wound was undertaken under general anesthesia. An excision of the affected area was performed, with histological analysis confirming endometriosis. This case highlights that extra-peritoneal endometriosis is a rare but treatable cause of recurrent, cyclical pelvic pain and swelling in the perineum. A high index of clinical suspicion is required due to its ability to mimic other pathologies, including abscesses and cysts. The primary management of perianal endometriosis is surgical excision. Where complete excision is not possible, medical management with hormone therapy should be considered.

Clinical presentation of perineal endometriosis and prognostic nomogram after surgical resection

Background

This retrospective study evaluated the clinical features of perineal endometriosis (PEM) and established a prognostic nomogram for recurrence probability in patients treated with surgical resection.

Methods

This study enrolled 130 PEM patients who had received surgical treatment in Peking Union Medical College Hospital (PUMCH) between January 1992 and September 2020. We collected their clinical features and conducted outpatient or telephone follow-up. The predictive nomogram was constructed based on 104 patients who had completed follow-up by July 2021. The Cox proportional hazards regression model was used to evaluate the prognostic effects of multiple clinical parameters on recurrence. The Index of concordance (C-index) and calibration curves were used to access the discrimination ability and predictive accuracy of the nomogram respectively, and the results were further validated via bootstrap resampling. Calculating the area under the curve (AUC) via risk scores of patients aimed to further access the predictive power of the model. In addition, the survival curve was depicted using Kaplan–Meier plot and compared by log-rank method.

Results

Most PEM patients had been symptomatic for 24–48 months before the lesion resection. With a median 99.00 (interquartile range: 47.25–137.50) months of postoperative observation, there were 16 (15.1%) out of 104 cases who finished follow-up reported symptomatic recurrence. On multivariate analysis of derivation cohort, multiple lesions, microscopically positive margin (mPM) and anal sphincter involvement (ASI) were selected into the nomogram. The C-index of the nomogram for predicting recurrence was 0.84 (95% CI 0.77–0.91). The calibration curve for probability of recurrence for 36, 60 and 120 months showed great agreement between prediction by nomogram and actual observation. Furthermore, the AUCs of risk score for 36, 60 and 120 months were 0.89, 0.87 and 0.82 respectively.

Conclusions

PEM is a rare kind of endometriosis and surgery is the primary treatment. Multiple lesions and ASI are independent risk factors for postoperative recurrence, and wide resection with more peripheral tissue could be preferred. The proposed nomogram resulted in effective prognostic prediction for PEM patients receiving surgical excision. In addition, this predictive nomogram needs external data sets to further validate its prognostic accuracy in the future.

Diagnosis and Treatment of Vulvo-Perineal Endometriosis: A Systematic Review

Objective: To describe the available knowledge on vulvo-perineal endometriosis including its diagnosis, clinical management and recurrence rate.

Methods: We followed the PRISMA guidelines for Systematic Reviews and our study was prospectively registered with PROSPERO (CRD42020202441). The terms “Endometriosis” and “Perineum” or “Vulva” were used as keywords. Cochrane Library, Medline/Pubmed, Embase and Clinicaltrials.gov were searched. Papers in English, Spanish, Portuguese, French or Italian from inception to July 30, 2020 were considered. Reference lists of included articles and other literature source such as Google Scholar were also manually scrutinized in order to identify other relevant studies. Two independent reviewers screened potentially eligible studies according to inclusion criteria.

Results: Out of 539 reports, 90 studies were eligible including a total of 283 patients. Their mean age was 32.7 ± 7.6 years. Two hundred sixty-three (95.3%) presenting with vulvo-perineal endometriosis have undergone either episiotomy, perineal trauma or vaginal injury or surgery. Only 13 patients (4.7%) developed vulvo-vaginal endometriosis spontaneously i.e., without any apparent condition favoring it. The reasons that motivated the patients to take medical advice were vulvo-perineal cyclical pain increasing during menstruations (98.2% of the patients, n = 278). Out of the 281 patients for whom a clinical examination was described, 274 patients (97.5%) showed a vulvo-perineal nodule, mass or swelling while six presented with bluish cutaneous lesions (2.1%) and 1 with bilateral polyps of the labia minora (0.4%). All but one patients underwent surgical excision of their lesions but only 88 patients (28.1%) received additional hormonal therapy. The recurrence rate was 10.2% (29 patients) considering a median follow-up period of 10 months (based on 61 studies).

Conclusion: In conclusion, vulvo-perineal endometriosis is a rare entity with approximately 300 cases reported in the literature since 1923. With the available knowledge shown in this systematic review, we encourage all practitioners to think about perineal endometriosis in case of perineal cyclical pain with or without previous perineal damage. Diagnosis should be done with clinical exam, perineal ultrasound and pelvic MRI when available. In case of anal sphincter involvement, perianal ultrasound should be performed. Surgical excision of the lesion should be realized in order to remove the lesion and to confirm the diagnosis histologically. Hormonal treatment could be proposed to attempt to decrease the size of a large lesion before surgery or to avoid recurrence of the lesion. As evidence-based approach to the diagnosis, treatment and recurrence rate of affected patients remains a challenge given its low prevalence, the variations in management found in the articles included and the limited quality of available studies, we suggest that a prospective database on vulvo-perineal endometriosis should be generated to increase knowledge but also awareness among healthcare professionals and optimize patients' care.

Systematic Review Registration:https://www.crd.york.ac.uk/prospero/, identifier: CRD42020202441.