Primary Inguinal Endometriosis: Neuroanatomy Beyond the Pelvis

INTRODUCTION: Primary inguinal endometriosis represents a rare manifestation of deeply infiltrating disease occurring outside the true pelvis. This was first described by Frederick Christopher in 1927, and since then fewer than 150 publications have been cited in peer-reviewed literature. Because of its atypical location, inguinal endometriosis often poses diagnostic challenges, with symptoms commonly misattributed to hernia, lymphadenopathy, or other groin pathology. Historically, surgical management has been performed through an abdominal or groin approach, often in collaboration with general surgery due to familiarity with the anatomy or need for fascial repair. These approaches may be limited by reduced visibility of adjacent neurovascular structures, potentially impacting the ability to resect the entire lesion. OBJECTIVE: We present an unusual case of primary inguinal endometriosis managed laparoscopically, demonstrating how this approach allows for improved neuroanatomic visibility and facilitates a more comprehensive, yet safe resection that reduces the surgical risk and perhaps recurrent pain. Our objectives are to focus on targeted groin anatomy using known landmarks to guide the dissection, and techniques to minimize neurovascular injury. METHODS: A reproductive-aged patient presented with dysmenorrhea previously managed with traditional combined oral contraceptive pills, and progressively worsening right groin pain and swelling. Clinical examination revealed a large, firm, and tender nodule in the inguinal canal. Imaging with ultrasound and magnetic resonance imaging demonstrated a heterogeneous lesion in the inguinal canal infiltrating the surrounding abdominal wall musculature. She was initially treated with a gonadotropin-releasing hormone antagonist, which resulted in significant volume reduction of the lesion. She then underwent laparoscopic surgical excision. Intraoperative video captured the dissection and highlighted critical anatomic landmarks, focusing on the lateral and medial nerves originating from the lumbar spinal nerve roots. RESULTS: The perioperative course was uneventful, with significant reduction in pain symptoms and minimal subjective impact from intentional transection of the femoral branch of the genitofemoral nerve that would have limited complete excision. No recurrence in pain has been observed to date. CONCLUSIONS: Primary inguinal endometriosis is an uncommon but important diagnostic consideration in patients with cyclical groin pain. Laparoscopy provides very clear visualization of the inguinal canal and surrounding neurovascular anatomy, allowing for comprehensive and safe excision of disease. This minimally invasive approach may reduce operative risk and recurrence while allowing for management of other pelvic disease. This case underscores the importance of anatomic awareness and surgical innovation in managing rare manifestations of endometriosis.