Uncommon Presentations of Endometriosis: Clinicopathological Features of Abdominal Wall and Extrapelvic Lesions.

Background/Objectives: Abdominal wall and extrapelvic endometriosis are uncommon entities that may mimic other surgical conditions and delay diagnosis. This study evaluated their clinicopathological, diagnostic, and surgical features in a single-center case series. Methods: This retrospective study included 29 patients with histopathologically confirmed abdominal wall or extrapelvic endometriosis treated at a tertiary referral center between 2009 and 2025. Demographic and clinical characteristics, surgical history, CA-125 levels, imaging findings, lesion size, and surgical features were analyzed. Abdominal wall cases were further evaluated based on the presence of muscle or fascial invasion. Results: Abdominal wall lesions comprised 93.1% of cases, while extrapelvic lesions (6.9%) were all vaginal. Most cases had a history of cesarean section; however, one patient had no prior abdominal surgery, consistent with spontaneous disease, with concomitant endometrioma and deep infiltrating endometriosis. Muscle or fascial invasion was observed in 63.0% of cases. Both CA-125 levels (p = 0.005) and CA-125 positivity (≥35 U/mL) (p = 0.029) were significantly higher in patients with invasion. Cyclic symptoms were present in 89.7% of patients, and mesh repair was required in two cases with large lesions. Conclusions: Abdominal wall endometriosis should be suspected in patients with cyclic pain or swelling at surgical sites, particularly after cesarean delivery, although it may occur without prior surgery. Deep muscle and fascial invasion may be associated with elevated CA-125 levels and increased CA-125 positivity, sometimes requiring wider excision and mesh repair. These findings may support earlier diagnosis and surgical planning.