Abdominal scar endometriosis: A case report and review of literature

Endometriosis is a clinical entity characterized by the abnormal presence of endometrial-like tissue implanted outside the uterine cavity. Although etiology remains unknown, it is considered to be hormone mediated and is associated with menstruation. It is the most common cause of chronic pelvic pain in females. With an estimated prevalence of 1-2% in women of reproductive age, it is more commonly seen in (15-25%) women with infertility problems.[] Depending on the location of ectopic endometrial tissue, it can be either endopelvic or extra-pelvic. The most common sites within the pelvis are the ovaries, fallopian tubes and uterosacral ligaments, whereas the extrapelvic endometriosis usually affects the abdominal wall, episiotomy scars, urinary and gastrointestinal tract, nasal mucosa, and the thorax.[] Abdominal wall endometrioma is one such variety of extrapelvic endometriosis having an incidence of less than 1%.[] Abdominal wall endometriosis mostly occurs following obstetrical and gynecological surgeries and is often confused with other surgical or dermatological conditions. CASE REPORT A 30-year-old multiparous woman presented to our gynecology out-patient department with chief complaints of gradually increasing swelling and pain at the left side of the previous caesarean scar for the past 1 year. The pain was continuous, dull aching type and typically increased in severity during her menses. The patient had consulted several physicians, general surgeons and dermatologist in the past 1 year for the same and was prescribed medications but she did not find any symptomatic relief. She gave history of previous two cesarean sections and her last child birth was 4 years back. Her menstrual cycles were otherwise regular and there was no complaints of urinary or bowel disturbances. Her general examination was within normal limits and vitals were stable. Abdominal examination revealed a circumscribed mass of 2 × 2 cm at the left end of the Pfannenstiel scar which was firm in consistency, with minimal tenderness and restricted mobility. An ultrasound abdomen revealed an ill-defined hypoechoic lesion measuring 2.0 × 1.9 × 1.3 cm with no significant vascularity on color Doppler in the subcutaneous plane at the left side of the scar region suggestive of scar endometriosis. MRI Pelvis showed a T2 hypo-intense irregular well defined lesion of the same size in the left antero-lateral lower abdominal wall, involving the deep subcutaneous plane as well as the superficial part of the left lower rectus abdominis muscle [Figure 1]. The lesion also showed multiple subcentimeter cysts with internal foci of blooming which was suggestive of endometriosis. She underwent surgical excision under spinal anesthesia. Intraoperative findings revealed a 3 × 2.5 cm firm mass in the subcutaneous plane infiltrating the rectus sheath and penetrating the left rectus abdominis muscle to a depth of about 1 cm. Wide surgical excision of the endometriotic mass was performed. Grossly, the specimen measured approximately 3.5 cm in its entirety and the cut section revealed a red-white, hemorrhagic, and mottled surface [Figure 2]. Histopathological examination showed muscle bundles, endometrial glands, endometrial stroma and occasional hemosiderin containing macrophages [Figures 3 and 4], thereby confirming the diagnosis of scar endometriosis. She had an uneventful postoperative period and is on regular follow-up.

Cutaneous scar endometriosis is a rare entity developing after gynecologic surgeries and caesarean sections. The incidence of scar endometriosis following a Cesarean section ranges from 0.2 to 0.8%.[,] The time interval between the operation and onset of symptoms usually varies from 3 to 6 years.[] The most common clinical symptom is a constant localized abdominal pain which typically exacerbates with the onset of menstruation. Sometimes a palpable mass can also be felt in the affected area. The pathogenesis of abdominal wall endometrioma is complicated and various theories have been proposed of which the most accepted is the “implantation or reflux theory” wherein the endometrial tissue passes through the fallopian tubes and attaches at ectopic sites. The refluxed extrauterine endometrial tissue can then be iatrogenically transplanted during gynecologic or obstetric procedures, such as during a Cesarean section.[] The “inoculation or the direct transport theory” states that, scar endometriosis is thought to result from direct transportation of endometrial tissue during surgical procedures wherein bits of endometrial tissue gets trapped in the incision site at the time of surgery giving rise to endometriotic deposits and subsequently under estrogen stimulation produces an endometrioma.[] Some other theories include the “coelomic metaplasia” theory which proposes that primitive pleuropotential mesenchymal cells lining the pelvic peritoneum undergo differentiation and metaplasia resulting in development of abdominal wall endometriomas.[] Ultrasonography with color Doppler reveals a solid, hypoechoic lesion with internal vascularity containing cystic spaces. CT and MRI though nonspecific can guide us in preoperative determination of the extent of involvement of deeper subcutaneous plane and rectus sheath infiltration. MRI has better contrast resolution than CECT and can detect even smaller lesions and hemorrhage within the endometrial lesion.[] Medical treatment is not effective in scar endometriosis and can only partially alleviate the symptoms. Wide surgical excision with at least 1 cm clear resection margin is considered the treatment of choice for scar endometriomas in order to prevent recurrence as well as to avoid possible malignant transformation from repeated recurrences. The risk of malignant transformation to endometrioid and clear cell carcinoma is up to 1% in recurrent cases.[] Depending on the extent of resection, a skin flap transplantation or mesh-reconstruction to cover the fascial defect might be required. Incomplete surgical resection or accidental exposure of the endometriotic tissue during surgery might result in recurrences. High pressure saline irrigation of the wound edges during abdominal closure at the time of the primary surgery can prevent the future development of endometrioma. Postoperatively, hormonal therapies such as GnRH agonists, gestrinone, danazol, or oral contraceptives could be considered to provide symptomatic relief and reduce recurrence though they are not much effective.

We have reported a case of abdominal scar endometriosis at previous cesarean scar site, wherein the diagnosis was unduely delayed due to lack of awareness of this condition among physicians, dermatologists, and general surgeons. One should have a high index of suspicion of scar endometriosis when a woman presents with a painful swelling on the abdominal scar especially with a history of previous gynecological or obstetrical surgery, in order to timely diagnose and treat this condition. Contributions VS and VK managed the case. VK, AS, & VS did literature search and drafted the manuscript. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

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