Abdominal wall endometriosis in a postcesarean patient: A case report and comprehensive review of diagnostic approaches and management strategies

We report the case of a 43-year-old female patient with no significant medical history, except for a prior C-section. In 2018, she sought medical attention for an 18-month history of cyclic pain in the left iliac fossa, occurring 8 days after menstruation. She had no other associated symptoms and no history of abnormal uterine bleeding. Over time, the pain progressively increased in intensity and duration, prompting her to seek evaluation at our institution. Physical examination revealed a palpable mass over the rectus abdominis muscle in the left suprapubic region, with no signs of skin inflammation. A soft tissue ultrasound was subsequently performed ( Fig. 1 ). Based on the presence of a solid mass in the deep soft tissues of the hypogastrium, a contrast-enhanced pelvic MRI was performed ( Fig. 2 ). Fig. 2 Contrast-enhanced pelvic MRI. MRI reveals a well-defined, fusiform mass in the suprapubic region, located along the midline and left paramedian area of the abdominal wall, predominantly involving the left rectus abdominis muscle. The lesion appears isointense on the T1-weighted sequence with fat saturation (A), hypointense on T2-weighted images (B and C), and demonstrates central diffusion restriction (D). After contrast administration, homogeneous enhancement is observed (E). The mass spans the entire anteroposterior diameter of the left rectus abdominis muscle, without involvement of the deep adjacent fat or evidence of subcutaneous tissue infiltration. Fig 2: Contrast-enhanced pelvic MRI. MRI reveals a well-defined, fusiform mass in the suprapubic region, located along the midline and left paramedian area of the abdominal wall, predominantly involving the left rectus abdominis muscle. The lesion appears isointense on the T1-weighted sequence with fat saturation (A), hypointense on T2-weighted images (B and C), and demonstrates central diffusion restriction (D). After contrast administration, homogeneous enhancement is observed (E). The mass spans the entire anteroposterior diameter of the left rectus abdominis muscle, without involvement of the deep adjacent fat or evidence of subcutaneous tissue infiltration. The patient underwent an ultrasound-guided biopsy, which yielded a histopathological diagnosis of endometriosis with scar fibrosis, negative for malignancy or granulomas ( Fig. 3 ). Immunohistochemical staining confirmed the diagnosis ( Fig. 4 ). Fig. 3 Microscopic histological description (Hematoxylin-Eosin, 10X). The specimen consists of mature fibroadipose tissue with well-circumscribed foci of glandular structures lined by pseudostratified columnar epithelium, featuring ovoid nuclei with homogeneous chromatin and occasional mitotic figures. These glands are surrounded by endometrial-type spindle cell stroma without cytologic atypia, along with areas of focal interstitial hemorrhage. Fig 3: Fig. 4 Immunohistochemistry (10X). (A) Estrogen receptors show positive immunoreactivity in both the glandular structures and the endometrial-like stroma. (B) CD10 exhibits positive immunoreactivity in the endometrial-type stroma. Fig 4 Microscopic histological description (Hematoxylin-Eosin, 10X). The specimen consists of mature fibroadipose tissue with well-circumscribed foci of glandular structures lined by pseudostratified columnar epithelium, featuring ovoid nuclei with homogeneous chromatin and occasional mitotic figures. These glands are surrounded by endometrial-type spindle cell stroma without cytologic atypia, along with areas of focal interstitial hemorrhage. Immunohistochemistry (10X). (A) Estrogen receptors show positive immunoreactivity in both the glandular structures and the endometrial-like stroma. (B) CD10 exhibits positive immunoreactivity in the endometrial-type stroma. Given the patient's clinical stability, she was scheduled for elective outpatient surgical resection of the abdominal wall endometrioma.

The reported case was reviewed and approved, and individual patient consent was obtained following institutional guidelines.

Endometriosis is a gynecological disorder that affects a significant proportion of women of reproductive age. It is characterized by the presence of endometrial tissue outside the uterine cavity, potentially involving the urinary tract, gastrointestinal tract, respiratory system, and abdominal wall [13] . Abdominal wall endometriosis (AWE) is a rare condition first described by Meyer in 1903 [14] . It is the most common site of extrapelvic endometriosis, with an incidence ranging from 0.03% to 1% [4] , although more recent studies suggest rates between 0.3% and 3.5% as noted in the introduction [ [1] , [2] , [3] ]. Cesarean section scars are the most common site of occurrence, followed by the anterior pelvic wall [5 , 6 , 15] . However, it has also been reported in laparoscopic trocar sites, Bartholin's gland incision sites, and perianal episiotomy scars [7 , 8] . In the absence of a prior surgical history, the umbilicus is the most common site of abdominal wall involvement [4 , 9] . This form of endometriosis is challenging to diagnose due to the nonspecific clinical presentation of abdominal wall pain associated with menstruation. The pathognomonic triad mentioned in the introduction—cyclic abdominal pain, palpable mass, and history of abdominal surgery—while helpful, is not always present. However, up to 57% of patients are asymptomatic and have no history of peritoneal endometriosis [16] . This finding supports the theory that its pathophysiology is linked to the migration of endometrial cells into the surgical wound at the time of the procedure [16] . Abdominal wall endometriosis is considered a benign condition, with a risk of less than 1% for developing clear cell carcinoma [17] , However, advanced age, postmenopausal status, and tumor size greater than 9 cm are considered risk factors for malignant transformation [17] . The imaging diagnosis of abdominal wall endometriosis (AWE) relies on a combination of imaging modalities. Ultrasound is the first-line diagnostic tool, as it typically reveals hyperechoic or isoechoic masses with peripheral vascularization. Computed tomography (CT) is useful for assessing disease extent, with lesions often appearing as slightly hyperdense relative to the muscle and exhibiting irregular margins. Magnetic resonance imaging (MRI) plays a key role in detecting small lesions and peritoneal endometriosis, particularly for nodules larger than 3 cm as mentioned earlier, with T1-weighted sequences demonstrating hyperintensity due to the hematic content of the lesions [18] . Among the differential diagnoses of abdominal wall lesions involving the muscular plane, desmoid tumors should be considered. These benign fibroblastic neoplasms account for approximately 0.03% of all tumors and are more commonly observed in individuals between 20 and 40 years of age. On imaging, they typically appear as well-circumscribed, homogeneous masses across various modalities. They may exhibit a muscle-like appearance, show vascularity on color Doppler, and demonstrate variable contrast enhancement patterns [12] . The optimal treatment for abdominal wall endometriosis is wide local excision with tumor-free margins of at least 1 cm to minimize the risk of recurrence and malignant transformation [13] . This surgical approach was successfully implemented in our reported case of the 43-year-old female patient with postcesarean AWE. In conclusion, abdominal wall endometriosis presents a diagnostic challenge in clinical practice, requiring a multidisciplinary approach for both diagnosis and treatment. Early and accurate identification can significantly improve patients' quality of life, while effective communication among specialists is essential for the successful management of complex cases and the continuous advancement of clinical practice.

Endometriosis is characterized by the ectopic presence of endometrial glands and stroma outside the uterine cavity, affecting up to 10% of women of reproductive age [1 , 2] . Abdominal wall endometriosis (AWE) is a distinct form of extrapelvic endometriosis, first described by Meyer in 1903, with a reported incidence ranging from 0.3% to 3.5% [ [1] , [2] , [3] ]. It commonly affects cesarean section scars, anterior pelvic wall [ [4] , [5] , [6] ], laparoscopic trocar sites, and episiotomy scars [7 , 8] , while the umbilicus is the most frequent location in patients without surgical history [8 , 9] . The pathognomonic triad of abdominal wall endometriosis consists of cyclic abdominal pain, a palpable mass, and a history of abdominal surgery [3] . A history of abdominal surgery, particularly C-section, is the most significant risk factor for developing abdominal wall endometriosis [1 , 10 , 11] . Fig. 1 Soft tissue ultrasound of the abdominal wall. Ultrasound imaging of the muscular plane in the hypogastrium, corresponding to the cesarean section scar, reveals a solid lesion with heterogeneous echogenicity, predominantly hypoechoic, and an oval shape. Color Doppler evaluation demonstrates minimal vascular flow. The lesion measures 43 × 13 × 35 mm in longitudinal, anteroposterior, and transverse diameters, respectively. Fig 1: Soft tissue ultrasound of the abdominal wall. Ultrasound imaging of the muscular plane in the hypogastrium, corresponding to the cesarean section scar, reveals a solid lesion with heterogeneous echogenicity, predominantly hypoechoic, and an oval shape. Color Doppler evaluation demonstrates minimal vascular flow. The lesion measures 43 × 13 × 35 mm in longitudinal, anteroposterior, and transverse diameters, respectively. Abdominal ultrasound is the first-line imaging modality recommended for diagnosing abdominal wall endometriosis. Computed tomography (CT) is valuable for assessing disease extent, while MRI is preferred for nodules larger than 3 cm to optimize surgical planning [1 , 10] . Differential diagnosis should consider other abdominal wall lesions, particularly desmoid tumors in patients between 20 and 40 years of age [12] . We report the case of a 43-year-old female patient with a history of C-section who presented with cyclic pain in the left iliac fossa, progressively increasing in intensity and duration over 18 months. Clinical evaluation revealed a solid mass in the deep soft tissues of the hypogastrium, with subsequent histopathological confirmation of abdominal wall endometriosis. This case highlights the diagnostic challenges and management considerations for this rare condition, which requires a multidisciplinary approach.