Unraveling Inguinal Endometriosis Disguised as Hernia: A Case Report

Endometriosis (EM) is characterized by the abnormal growth of endometrial-like tissue outside the uterus, leading to a persistent inflammatory response. It predominantly affects women in their reproductive years, with an occurrence rate of 6–10% among healthy women. While it usually manifests within the pelvic region, extra-pelvic endometriosis has been documented in various anatomical sites, including the bladder, intestines, surgical scars, and hernial sacs. Inguinal endometriosis (IEM), a rare subtype involving the extraperitoneal segment of the round ligament, affects 0.3 to 0.6% of EM patients. This condition is often misdiagnosed as other groin disorders and is typically confirmed through histological analysis [1]. IEM was first reported in 1986, and cases remain scarce in the medical literature. It commonly presents in the right groin as a mass, which may cause cyclical pain or remain asymptomatic with menstrual-related symptoms. The mass size may fluctuate with menstrual phases or tend to bleed. Approximately, half of the patients report catamenial symptoms. The exact origins of IEM are not fully understood, but proposed mechanisms include mesothelial metaplasia, retrograde menstruation with hernial seeding, oxidative stress, and inflammatory and autoimmune responses [2]. The rarity of IEM and its frequent association with pelvic EM complicate its diagnosis, especially when it co-occurs with inguinal hernia and other groin lesions [1]. This case report contributes valuable information to the growing knowledge of the diverse clinical presentations of EM. It underscores the importance of prompt identification and individualized treatment strategies to improve outcomes for patients with extra-pelvic endometriotic conditions. Case Report A middle-aged multiparous woman presented with a six-month history of gradually increasing right groin swelling accompanied by pain that coincided with her menstrual cycle. Previously, she experienced regular menstrual cycles without dysmenorrhea, dyspareunia, or infertility. Her surgical history included prior caesarean sections. On physical examination, the patient had a soft, non-distended abdomen that was tender upon palpation in the right lower quadrant. Notably, an irreducible, relatively mobile, firm mass measuring 6 cm by 4 cm was found in her right inguinal region. The absence of a cough impulse and bowel sounds suggested an irreducible inguinal hernia. Ultrasound imaging revealed multiple hypoechoic lesions with solid and liquid components in the pelvis, indicative of pelvic EM and a complex cystic formation extending through the right inguinal canal. This cyst closely followed the round ligament and showed no peri-lesional fat stranding. Her baseline biochemical parameters were within normal ranges. After discussing with the patient, it was decided to perform an elective total abdominal hysterectomy with bilateral salpingo-oophorectomy to treat the pelvic EM, along with the excision of the groin mass. During surgery, after completing the hysterectomy and salpingo-oophorectomy, careful exploration of the right inguinal canal revealed a cystic structure measuring 6 cm by 4 cm extending along the round ligament towards the mons pubis, as shown in Fig. 1. The cyst was dissected from the round ligament and excised. Upon incision, it contained a clear liquid. The patient’s postoperative period was uneventful, and she was discharged on the third day post-surgery. Histopathological examination of the excised specimen showed endometrial glandular epithelium with hemosiderin-laden macrophages and fibrosis, confirming EM in the right inguinal canal, as depicted in Fig. 2. The patient was referred to gynaecological care for further evaluation and management. A three-month follow-up showed no recurrence, and the patient remained asymptomatic.

Identifying IEM is challenging and often confused with common conditions such as hernias, tumours, cysts, lymphadenopathy, granulomas, and hydroceles. Approximately, half of IEM patients exhibit catamenial symptoms, such as changes in size and tenderness, which should alert clinicians to the possibility of IEM. The rarity of IEM, its unusual location, variable pain patterns, and inconclusive ultrasound results contribute to frequent misdiagnosis, often as inguinal hernia. IEM is predominantly found in the right groin, possibly due to the clockwise circulation of peritoneal fluid, obstruction by the sigmoid colon, and the round ligament’s role as a conduit from pelvic EM to the groin. Pathological examination is crucial, revealing endometrial glands and stromal cells within connective tissue. The pathogenesis of IEM still needs to be fully understood, and its association with cesarean delivery is unclear [1]. Preoperative diagnosis is difficult due to the non-specificity of catamenial symptoms and the tendency of patients to consult general surgeons rather than gynaecologists. Imaging techniques like ultrasound and magnetic resonance imaging can aid in diagnosis, but histological examination is definitive. A patient’s history of menstrual-related groin swelling or uterine surgery can be indicative, yet histological confirmation is necessary. While pelvic EM is common, extra-pelvic manifestations are significant and often associated with previous surgeries. IEM lesions rarely occur without prior surgery [1]. Ultrasound is the initial imaging choice for inguinal lesions but has limited value for diagnosing IEM. IEM often appears as indeterminate hypoechoic, heterogeneous, or cystic masses in the ultrasound, resulting in a low preoperative diagnosis rate. Drug treatment for IEM needs to be well documented and remains debatable. Hormone suppression therapy is generally reserved for patients with pelvic EM-treated laparoscopically and is not deemed necessary for isolated pelvic ectopic EM cases. In most cases, the primary treatment for IEM involves surgical intervention, focusing on thorough lesion excision to prevent recurrence. During IH surgery, if a surgeon encounters signs suggestive of IEM, such as thickened hernia sac walls or purple-blue lesions, a gynaecologist should be consulted for further assessment and potential complete removal of the IEM lesion. This is particularly crucial for patients with infertility, where laparoscopic examination may also be warranted [1]. To reduce the risk of EM implantation during surgery, it is advised to irrigate the site with saline and change surgical materials before closing the wound. Post-surgery, especially in infertile women, a gynaecological evaluation is essential due to the potential coexistence of pelvic EM. Treatment should be coordinated between general practitioners and gynaecologists. Preoperative hormone therapy may be considered for larger suspected IEM lesions to facilitate complete removal. Some experts suggest concurrent laparoscopy to assess for pelvic EM, given its association with IEM [1, 3, 4]. The comprehensive removal of the round ligament and hernia sac is vital to prevent recurrence, although more clinical evidence is needed to confirm this. Since IEM can coexist with IH and conditions like peritoneal pseudomyxoma or malignancies might be present, wide removal and pathological examination of the hernia sac are recommended [1]. Gynaecological assessment is crucial, particularly for infertile patients, to manage pelvic EM concurrently. Effective treatment includes complete surgical excision, cautious management to prevent recurrence, and hormonal therapy. Referral to gynaecology is advised as pelvic EM often accompanies IEM. After proper surgical resection, IEM seldom recurs, and postoperative hormonal therapy is generally not necessary for isolated pelvic EM cases [1–4].

The present case report contributes to the growing body of knowledge surrounding the diverse presentations of EM, emphasizing the critical role of early recognition and individualized management in optimizing patient outcomes in extra-pelvic endometriotic manifestations. Author contributions S Aishwarya, K B Ranjith, M A Balakrishna, S Chandrashekar: diagnosis, surgical management and histopathological assessment, conceived the idea, review of literature, drafting the manuscript, revision of manuscript and final approval. Funding The authors wish to confirm that there is no external source of funding to disclose pertaining to this study. Data availability This study encompasses all data generated or scrutinized within its scope, comprehensively integrated within this case report. Declarations Conflict of interest The authors declare that they have no conflict of interest or competing interests. Ethical approval Approval was obtained from the Institutional Ethics Committee. The procedures used in this study adhere to the tenets of the Declaration of Helsinki. Consent to participate Written informed consent was obtained from the participant. Consent to publish The participant has consented to the submission of the case report to the journal. Footnotes S. Aishwarya is a Post Graduate Resident; K. B. Ranjith is a Associate Professor; M. A. Balakrishna is a Professor and Head; and S. Chandrashekar is an Assistant Professor. Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

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