Abstract
Abdominal scar endometriosis is a rare condition of extrapelvic endometriosis that poses a diagnostic difficulty, which usually develops in a surgical scar of Caesarean section, hysterotomy or hysterectomy. The development of a mass in a surgical scar poses a diagnostic dilemma due to similarities in appearance to incisional hernias, abscesses, granulomas, hematomas or desmoid tumors. The aim of this article is to review the incidence, pathophysiology, clinical findings, imaging results, histopathology, treatment and prevention of this condition . And the emphasis is also given to include Abdominal scar endometriosis in the differential diagnosis of masses located at abdominal incision scar following a previous obstetric and gynecologic surgeries, which should be excised for definitive diagnosis and treatment.
Keywords: Endometriosis, Abdominal scar, Scar endometriosis, Caesarean scar
Introduction
Endometriosis was first described by Rokitansky in1860It is the presence of functioning endometrial glands and stroma outside the normal linning of the uterine cavity under the influence of female hormones . It is a common disease that involves approximately 10–15% of women of reproductive age.It is a chronic, often recurring disease of complex and unclear etiology. It has a variety of symptoms such as menstrual pain, pelvic pain, dyspareunia, and infertility. Endometriosis has intra and extrapelvic localization. It is frequently detected in the pelvic organs, such as the peritoneum, the ovaries, the pouch of Douglas and the uterosacral ligaments3.
Incidence
Extrapelvic endometriosis is less common. It can occur in every organ of the body, including the gall bladder, gastrointestinal tract, skin, appendix, kidney, and lung. Hernial sacs, abdominal wall, and surgical scars also are sites of involvement. Abdominalscar endometriosis is reported to occur in 0.03–1.08% of women after obstetric or gynecologic surgeries, particularly after hysterotomy4. The incidence following caesarean section is reported to be 0.03–0.4%, and following hysterotomy, the incidence is 2%5. Endometriosis, in patients with scars, is more common in the abdominal skin and subcutaneous tissue. Endometriosis involving only the rectus muscle and sheath is very rare6.
First case of scar endometriosis was reported by Meyer in 19037. The presence of endometriosis in cesarean section scars have been documented in gynecologic literature since 19565. Incidence rates for endometrioma associated with cesarean section incisions have been reported to be 0.03–1.7% Abdominal Scar endometriosis presents clinically as a painful, palpable subcutaneous mass, associated with cramps and bloating during menses. It is easily confused with other conditions, such as keloids, haematoma, stitch granuloma, abscess, inguinal and incisional hernia 9. Caesarean scar endometriosis is the most frequently reported form of this disorder and is usually benign, although a malignant transformation has been reported10.
Cutaneous involvement is less than 1% of all cases of endometriosis11, and in most cases of such involvement it is found on obstetric and gynecologic surgical sites of the abdomen or perineum following hysterectomy, hysterotomy, Caesarean section, perineotomy, or laparoscopy12.
Pathophysiology
The proposed theories of endometrioma formation are:
Retrograde spread of collections of endometrial cells during menstruation
Blood, lymphatic or iatrogenic spread
Metaplasia of the pelvic peritoneal cells
Immune system dysfunction and autoantibody formation13
The development of intrapelvic endometriosis may involve retrograde menstruation, maturation of extrauterine primordial cell remnants of embryogenesis and hematologic or lymphatic spread of endometrial cells. The pathogenesis of cesarean scar endometriomas is best explained by a combination of theories direct implantation during a surgical procedure on the endometrium14. According to Celik M6, the most practical and popular theory is that of direct implantation. During caesarean section, endometrial tissue is seeded into the wound. From this point, the tissue either proliferates under the same hormonal influences as endometrium in utero or induces endometrioma by one of the mechanisms described above metaplasia of the surrounding fascial tissue to form an endometrioma. Alternatively, endometrial cells may reach a caesarean scar via lymphatic or haematogenous routes.
Diagnosis
Clinical diagnosis remains difficult, and many patients are asymptomatic15. The diagnosis of Abdominal scar endometriosis can be made by a careful history and physical examination. The patients present with a mass near the previous surgical scars, accompanied by increasing colicky-like pain during the menstruation. Usually, there is a history of a gynecologic or rarely a nongynecologic abdominal operation. In these patients, correct diagnosis relies on careful examination, right questioning, and obviously taking endometriosis in consideration16. A history of previous caesarean section, the presence of a lump increasing in size in the scar, symptoms of pain, bleeding, and skin discoloration can be diagnostic clues for Abdominal scar endometriosis; rarely, caesarean scar endometriosis can present as an acute abdomen11.
Generally, the mass develops between the skin and the abdominal fascia and does not grow in the peritoneum17. In the literature, the mean size of masses has beenrange 1.5–4.8cm. Patients may present from months to years (mean 21 mo) after their last obstetric/gynecologic surgery.
The most common site of Abdominal scar endometriosis is near a pfannenstiel incision. This is possibly related to the wider dissection of the tissue planes when compared to vertical midline incision. Teng et al4, have reported 19 cases of Incisional Endometriosis in pfannenstiel incision, 18 of which were done for caesarean section and one for hysterotomy.
Ultrasonography, CT scan, and magnetic resonance imaging are useful noninvasive techniques when the differential diagnoses are numerous or more information about a known endometrioma is needed. Some papers suggest that a preoperative needle biopsy should be performed18whereas, ultrasonography is the best and most commonly used imaging investigational procedure for abdominal masses, given its practicality and lower cost.
On colour Doppler study, the majority of the cases showed a single vascular pedicle entering the mass at the periphery. Some cases demonstrate intralesional vascularity. In a minority of cases there may not be any detectable vascularity on colour Doppler examination19. CT scan with IV contrast characteristics of Abdominal scar endometrioma is of inhomogeneously enhancing soft tissue density mass lesion. The irregular margins infiltrating the surrounding fat will be seen. CT has no pathognomonic findings of endometrioma and it is less useful in distinguishing the endometrial tissue from the surrounding structures as compared to MR imaging20.
Kinkel et al21. revealed the sensitivity and specificity of MRI in diagnosing endometriomas to be 90%–92% and 91%–98%, respectively. MRI is also a useful modality for presurgical mapping of deep pelvic endometriosis. Infiltration of abdominal wall and subcutaneous tissues is much better assessed by MRI. Furthermore, MRI with intravenous gadolinium was very useful for presurgical mapping of the scar endometriosis by accurately defining the infiltration of the adjacent abdominal wall muscles and subcutaneous tissues21. Contrast-enhanced dynamic MR imaging (DMI) in the diagnosis of nodular abdominal endometriosis has been reported to be useful22.
Fine-needle aspiration cytology (FNAC) was reported in some studies for confirming the diagnosis23. Cytology smears show sheets of epithelial cells, spindled stromal cells and a variable number of hemosiderin laden macrophages. The stromal cells are plump, spindled and arranged around a vascular meshwork. The presence of any two of the three components is required for the diagnosis of endometriosis . However, these cytological features are related to harmonal changes. In proliferative phase, epithelial cells are cohesive sheets of uniform small cells with small scant of cytoplam, round to ovoid nuclei with band chromatin and occasional non-atypical mitosis. While during secretory phase, cell size gradually increases with cytoplasmic microvacuolations , with predecidual changes and epithelioid appearance in stromal cells, causing diagnostic difficulties.
Management
Various treatment modalities used in the management of pelvic endometriosis are also available to manage intrapelvic endometriosis, all of which depend primarily on creating a hypoestrogenic environment that deprives the endometriosis of nourishing hormonal stimulation. Low-dose estrogen oral contraceptives are often used to alleviate pain from endometriosis and limit the extent of cell growth..
In some patients, the effects can be relatively long-lasting, but complete, permanent regression of endometriosis is rare with medical therapy. The success rate of medical therapy has been reported to be low, offering only temporary alleviation of symptoms often followed by recurrence after cessation of the drug. Moreover, due to side effects such as amenorrhoea, weight gain, hirsutism, and acne, compliance is unlikely. Local wide excision, with at least a 1 cm margin, is accurate treatment choice of Abdominal scar endometriosis also for recurrent lesions. In large lesions, complete excision of the lesion may entail a synthetic mesh placement or tissue transfer for closure after resection16. Because of the possible recurrence (4.3 % after surgery)24and malignant degeneration (0.3–1 %) of this condition, a local wide excision with at least a 1 cm resection margin is currently considered the best clinical practice25, although no studies have so far evaluated whether the surgical margin width affects the recurrence rate24.
Complication
The latest studies provided a definite proves for an increased risk of breast cancer, ovary cancer, melanoma and non-hodgkins lymphoma in woman who have endometriosis. These woman also have higher thyroiditis incidence, hypo and hyperthyroidism, autoimmune disease such as rheumatic arthritis, lupus sclerosis and Menier's disease and also their closest relatives, which undoubtly confirms the importance of immune component in the endometriosis development26.
Prevention
It is believed that Abdominal scar endometriosis results from iatrogenic inoculation of the fascia or subcutaneous tissues with endometrial cells during invasive abdominopelvic procedures. Therefore, it is strongly recommended that before closure, the abdominal wound must be thoroughly cleaned and irrigated vigorously with saline27.
Conclusion
Abdominal scar endometriosis, a common condition in extrapelvic endometriosis, is more frequent than generlly assumed, occasionally presents as a painful mass that may worsen pre or perimenstrually. It should be kept in mind in all premenopausal women presenting with cyclical pain over abdominal scar following a previous obstetric or gynecological procedures.
The cause of endometriosis is unclear and there are many proposed theories regarding the pathogenesis of the disease. Caesarean scar endometriomas is best explained by a combination of theories direct implantation during a surgical procedure on the endometriumor transportation to a cesarean section scar via lymphatic or hematogenous routes.
The diagnosis is based on findings obtained from accurate history taking and meticulous clinical examination. However, Ultrasonography, CT scan, and magnetic resonance imaging are useful noninvasive techniques to exclude the differential diagnoses whereasFNAC are indicated towards better diagnostic approach. Medical treatment may decrease symptoms for some time; however, to provide both diagnostic and therapeutic intervention, total surgical excision is considered to be the gold standard method. At the end of the procedures of gynecological and obstetrical surgeries, proper caution should be taken before closure to avoid endometrial transplantation to the abdominal wall by cleaning and irrigating vigorously with saline.
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