Endometriosis is defined as finding the functional endometrial layer outside the uterine cavity. It is one of the common gynecological disorders in women of reproductive age group. Its prevalence in the general population varies between 0.7% and 44%  . The common sites of occurrence of endometriosis are in the pelvis and especially the ovaries, uterosacral ligaments and round ligaments. Extra pelvic endometriosis is rare and it affects between 0.03% and 1.7% of reproductive age women. The most common sites are bladder, gastrointestinal tract, lungs, under the skin especially after obstetric surgical interventions  .
2. Case Report
A 37-year-old woman, Para 1 + 0, presented in emergency room with the complaint of pain and swelling on the Caesarean scar for one year. She had undergone one Caesarean section 2 years ago. She described pain above the right lateral one third of Caesarean scar that increased during the menstruation period.
Examination revealed an approximately 3 cm wide, tender, strict, and immobile right subcutaneous mass beneath the right third of Caesarean scar (Figure 1). Trans abdominal ultrasound showed ill-defined heterogeneous hypo echoic subcutaneous mass lesion measures approximately 3.5 × 2.3 × 3 cm (Figure 2). By applying color map few vessels seen within the lesion mainly periphery, arising the possibility of endometrioma (Figure 3). Hysterosalpingoram was done excludes any tubal communication or anatomical adherents (Figure 4).
Based on characteristic history, examination and ultrasound findings, the diagnosis is scar endometrioma. The mass excised in total (Figure 5) and histopathology confirmed scar endometriosis. Figure 6 shows foci of endometrial gland and stroma in the fibromuscular stroma. She was followed up in the clinic and there was no evidence of recurrence with normal menstrual cycle free of dysmenorrheoa.
Figure 1. Right site Caesarean section scar mass.
Figure 2. USS shows ill-defined heterogeneous hypoechoic subcutaneous mass.
Figure 3. Colour map shows few vessels seen within the lesion mainly periphery.
Figure 4. Hysterosalpingogram excludes any tubal communication.
Figure 5. The mass during excision.
Figure 6. Foci of endometrial gland and stroma in the fibromuscular stroma.
Surgical scar endometriosis is a rare condition. The main cause of surgical scar endometriosis is obstetric and gynecologic operations such as in the perineum following vaginal delivery with episiotomy and in abdominal surgery scar areas following hysterectomy and Caesarean section  . Scar endometriosis can be observed after procedures such as laparoscopy and amniocentesis   . The differential diagnosis are hematoma, suture granuloma, dermoid tumor, sarcoma, abscess and metastatic malignancy. The incidence of malignant transformation in scar endometriosis is 0.3% - 1% and it is diagnosed by histopathology after the surgery. The most commonly seen malignancy is clear cell carcinoma. The possibility of malignant transformation of the lesion considered in cases that recurrency after surgery  .
The most accepted etiology is implantation of endometrium at the time of surgical intervention  . Proper history taking and physical examination are the key for diagnosis. The most common findings are swelling, pain, and rarely bleeding in the lesion area. Menstruation-related pain and swelling in the history should be considered to be pathognomonic for scar endometriosis. Ultrasound scan is complimentary to the diagnosis in some cases. The definite treatment is surgical excision. The diagnosis is confirmed by the histopathological examination of the excised tissue.
Local wide excision, with at least 1 cm of margin, is the treatment of choice for scar endometriosis and recurrent lesions  . Recurrence of scar endometriosis is rare, with very few cases have been reported. Larger and wider lesions deeper to the muscle or the fascia are difficult to excise completely  . In large lesions, placement of synthetic mesh may be required. The incidence of concomitant pelvicendometriosis with scar endometriosis is ranging from 14.2% to 26%. Pelvic endometriosis should be ruled out in cases of scar endometriosis. These patients need to be followed up for few years for pelvic endometriosis.
Scar endometriosis is the possible first diagnosis in a mass at Caesarean section site with pain or discomfort associated with menstruation. Although malignant transformation of scar endometriosis is exceptionally rare, total surgical excision is the best option for both diagnosis and treatment.
Special thanks to Latifa Hospital administration, Obstetrics & Gynecology department, Radiology department, Anesthesia department, Theater staff and the Nursing staff for their unlimited cooperation and outstanding care in the patient management. Special Thanks to Ms. Norma L Cruz (Registered. Nurse) and Ms. Aileen L Omoso (Registered operation theater Nurse) for their appreciated help for this case.
Ethical clearance is obtained from the patient herself by written and informed consent as well from hospital administration.