{"paper_id":"e7e5cd95-d3c6-44db-813f-aac70ff97a94","body_text":"Endometrial tissue localized outside the uterine cavity is defined as endometriosis. It\ncommonly has been demonstrated in the ovaries, peritoneal surfaces, vagina, scar\ntissues, cervix, fallopian tubes, rectum, urinary tract, pouch of Douglas and possibly\nany organ in the abdomen 15 . The\nestimated prevalence reported in literature ranges from 8-15% 5 , 9 . Extra-pelvic\nlocalization of endometriomas are relatively rare. Especially abdominal wall placements\nare very infrequent. Usually such cases are associated with surgical scars 5 . The proposed mechanisms that have been\nput include retrograde menstruation, venous or lymphatic dissemination or metastasis,\nand mechanical transplantation into scars at the time of surgery 8 .\nHerein, is presented a case of endometrioma localized in the rectus abdominis\nmuscle.\n\nA 31 year old female with a history of two cesarean sections, the last one of them three\nyears prior, presented with a painful mass in the left lateral side of the Pfannenstiel\nincision which had been steadily growing. The same patient went a month ago to our\ninstitution's urology clinic with pain in the inguinal region. After a detailed history\nand physical examination an ultrasonography was performed that revealed a 20X12 mm\nhypo-echoic nodular mass, neighboring the rectus abdominis muscle, with minimal\nvascularization. The differential diagnosis included endometriosis and a possible\ndesmoid tumor. The patient was referred to our clinic for further evaluation. The pain\nstarted on the left lower quadrant and radiated towards the inguinal region, and was\nassociated with menstruation. In physical examination a 2 cm wide mass was palpated in\nthe previously described localization. Magnetic resonance imaging was performed which\nrevealed a 20x11 mm mass which is slightly hyper-intense in the T1 sequence, and\ncontrast enhanced after IV gadolinium injection in the T2 sequence, with increased\nsignal intensity and nodular appearance in diffusion weighted sequences. These were\nfound to be consistent with an endometrial implant ( Figures 1A  and  1B ). Examination of the\nuterine cavity showed effusion which was at most 15 mm in width when measured. A little\nfree fluid, indicating peritoneal irritation was present in between the intestinal\nloops. No pathological lymph nodes were present in the lower abdomen.\nArrows show the area of endometriosis in rectus abdominis muscle: A) CT scan in\ntransverse section; B) CT scan in sagittal section\nThe patient was admitted for surgical removal of the mass 2 cm wide fibrotic appearing\nmass was excised ( Figure 2 ) and was sent for\npathological examination. The patient's complaints resolved after the surgery. She was\ndischarged with no complications two days after the operation. Four months after the\nsurgery, the patient came in for a follow-up visit, and had no complaints or\ncomplications. Histopathological examination was consistent with glandular structures of\nthe endometrium with accompanying endometrial stroma within muscle and connective tissue\n( Figure 3 ).\nThe mass excised in the operation\nTypical endometrium glands and spindle endometrium stroma existed in the area of\nendometrosis (H&Ex50)\n\nEctopic endometrial tissue localized in the rectus abdominis tissue is a very rare\noccurrence. Previously there have been only 20 reported cases in literature 5 . The first one of these cases was\npresented by Amato et al. 2 , in 1984.\nGiannella et al. 7  has reviewed the\npreviously reported cases extensively; their clinico-pathological characteristics,\nsummarized, were: endometriosis with rectus abdominis placement usually is seen in\npremenopausal women, aged 27-42y, and history of previous surgery (77%), similarly to\nthis patient. The average size of the endometriomas were 4X4 cm in diameter. This case\nhad a much smaller dimension. The imaging studies' measurements were 2 cm at the\ngreatest width. While CT scan has most commonly been used, in this case imaging\ndiagnosis preferred to use ultrasound followed by an MRI 7 . Fine needle aspiration has also been tried in these\ncases; however, failed to prove effective in establishing diagnosis 3 .\nCesarean section is very frequently associated with abdominal wall endometriosis. The\nincidence, as reported in previous literature, can be as high as 1%. One of the proposed\ntheories for how this occurs, takes into consideration the possibility that during the\noperation, endometrial cells may escape through the incision in the uterus and implant\nthemselves within the abdominal incision site 3 .\nThis patient presented with cyclic symptoms that were associated with menstruation. The\ndifferential diagnosis of cyclic pain in general include lymphadenopathy, mesenteric\nlymphadenitis, lipoma, abscesses, hernias, hematomas, soft tissue sarcomas, desmoid\ntumors (which was considered in differential diagnosis) and even metastatic cancer.\nPreviously some studies have looked into the utility of biochemical markers for tracking\nendometriosis. These markers include CA-125, C-reactive protein, anti-mullerian hormone,\nfollistatin 6 , 11 , 12 , 13 .\nPreviously conducted sonographic studies have determined that abdominal wall\nendometriomas (which were first demonstrated via ultrasound in 1979 14 ) are commonly hypo-echoic, well defined,\nsolid masses; this is consistent with sonographic findings of this case 1 . Medical treatment for these conditions,\nwhich have been previously utilized in literature, include danazol and progesterone;\nhowever, this treatment is frequently inefficacious, and therefore must be reserved for\ncases in which surgical treatment is not preferred 10 .\nTo summarize, in masses which present with cyclic pain and growth, localized to the\nabdominal surface, endometriomas must be considered in the differential diagnosis.\nSurgical removal, as evidenced previously reported cases, is successful, especially when\nlimited and localized within in the rectus abdominis muscle. Sonography followed by\nresonance, provides the most definitive imaging. Molecular markers are currently not\nestablished enough to be considered as a standard of diagnosis. Further large-scale\nstudies or reviews are necessary to determine which approach is the best, with\nconsideration of the patient's request.","source_license":"CC0","license_restricted":false}