It is not very common for women to have inguinal endometriosis, a complication in which the groin is affected by strange lumps in women with endometriosis. In fact, it is projected that fewer than 1% of all patients with endometriosis are affected by inguinal endometriosis. The largest study to date investigating patients with inguinal endometriosis was conducted in seven hospitals in France and Lebanon, where only 42 cases of the condition were identified.

These rare reportings were published in the article, “The Groin: An Unusual Location of Endometriosis–A Multi-Institutional Clinicopathological Study,” which appeared in Journal of Clinical Pathology. The research team combed through their hospitals’ surgical pathology database and considered only patients with non-cutaneous and non-lymph node inguinal endometriosis. The average age of the 42 patients identified was 35 years of age.

Interestingly, only 31% of the patients were suspected to have endometriosis before undergoing surgery. The remaining patients were suspected to have a hernia (19%), a cyst (10%), an enlarged lymph node (10%), a tumor (2%), bladder diverticulum (2%), or a lump of some other origin. Lumps in the groin, as well as menstrual tenderness, were symptoms that affected the patients and caused the patients’ visits to the hospitals.

Upon resection, patients’ lumps were shown to be no more than 2 inches in diameter, but the lumps were firm and multinodular. The majority had these lumps on the right side of their body, perhaps due to asymmetric lymphatic drainage.

Due to the low rate of proper diagnosis, the researchers are urging clinicians who see patients with inguinal masses to consider the differential diagnosis of inguinal endometriosis. “Endometriosis should be included in the differential diagnosis of all inguinal masses in women of reproductive age,” they wrote. If this diagnosis is made, and patients undergo surgery, there is a high rate of success. According to the authors, “Wide surgical resection is usually curative.” By removing these lumps, clinicians can also ensure that the lumps are not becoming malignant and use the samples for future research to understand why the lumps form and negatively affect some patients with endometriosis.