Primary Rectal Teratoma Presenting as an Irritable Bowel-like Syndrome: A Case Report

Background : Teratoma is a tumor comprised of three germinal layers classified as mature or immature in most cases. Most mature solid teratomas are benign but may turn malignant; therefore, complete resection is advised in these cases. They usually occur in women. Primary rectal teratomas are infrequent, and only a few cases have been described in the literature. Teratomas are the most common cystic that rise in the ovary, testicle, and retroperitoneum. They can also be solid and are better known as dermoid cysts. Case Presentation: We report a 34-year-old woman who were presented with intermittent constipation and diarrhea in Urmia Imam Khomeini Hospital in January 2020. After examination, a solid intra-rectal teratoma occurring mainly in the rectum was detected in this case. The patient underwent segmental colectomy and histology, which revealed squamous epithelium, fat cells, hair follicles, cartilaginous material, and granuloma suggestive of mature teratoma. Conclusion: The present case was a solid primary rectal teratoma, an uncommon disease with many misdiagnoses that can be differentiated from other diseases. In this case report, it is differentiated from irritable bowel syndrome (IBS).

received drug treatment. The frequency of abdominal pain decreased after the initial treatment. However, the patient's pain gradually increased after one month, and she was re-examined and hospitalized with the same clinical presentation. According to physical examinations, she was fully conscious with a 100/70 mmHg blood pressure, a pulse rate of 90 beats/min, and a temperature of 37.6°C (Table 1). Abdominal examination showed slight tenderness of the lower abdomen. Based on digital rectal examinations, in addition to skin tags, the findings represented mild perianal erythema.
An ultrasound of the abdomen and pelvic revealed an echogenic mass with internal fluid on the right ovary, (78 * 48 mm) and echogenic internal material extended up to the left ovary. Another hypoechoic mass (98 * 37) mm including multiple collections with echo-free cysts with echogenic internal septate was detected on the right side of the pelvic in the omentum and intraperitoneal.
Abdominopelvic magnetic resonance imaging (MRI) demonstrated two cystic lesions located in the anterior uterus with a few thin septa suggestive of peritoneal inclusion cysts with some loculated fluid areas in the lower abdomen in the inter loop space. A cystic lesion (50*27*24 mm) was observed in the left adnexa (probably originated from the ovary) with an 8*5 mm T1 hyperintense component (probably, it was hemorrhage), showing rectal wall thickening. There was also an intramural-like area (33*18*14 mm) in the posterior The patient underwent endoscopic ultrasonography that represented a large heterogeneous mass lesion (88*45 mm) above the uterus with the areas of cysts degeneration and calcification invaded into the rectal wall and extended to the lumen resembling an exophytic pattern bulging from the serosa ( Figure 1).
On colonoscopy, a pedunculated polypoid (4*5 cm) lesion with a distance of 12 cm from the anal verge was detected that contained a tooth-like structure, and a few hairs were projected from the surface of the lesion (Figure 2).
Due to invasion in the mass and its large size, endoscopic tumor resection was extremely difficult; then, a surgical plan was inserted, and the patient underwent laparotomy, which revealed a mass in the rectum and an adhesion band with mesenteric granuloma. Segmental colectomy was performed, making colostomy after the release of abundant adhesion. The patient did not have any postoperative complications. Thus, she was discharged from the hospital a few days after the surgery and obtained adequate gas and feces control.
The histological examination of mesocolon mass showed squamous epithelium, granulomatosis inflammation, hair follicles, cartilaginous material, and columnar lining of the glandular structures suggestive of mature teratoma. After six months, the patient underwent computerized tomography (CT) scan for evaluation; no obvious intrapelvic abnormality was revealed, and sideto-side anastomosis was made after this time.

Discussion
Mature teratoma is a three-layered germ cell tumor commonly found in the ovary, testes, or mediastinum (3). Due to the lack of germ cells in the gastrointestinal tract, teratoma occurs less commonly in the digestive tract (4). It is believed that primary rectal teratoma only occurs when germ cell aberrantly enters the digestive tract. Primary rectal teratomas are scarce, and only a few cases have been described in the literature (5). Only 54 cases were reported in the world, and four cases have been published in Korea (6,7). Rectal teratoma is more common in women, with only one case reported in men. Teratoma is highly suspected when there is hair on the   (8,9). In this reported case, hairs were found on the out layer of the mass, which raised the suspicion of a rectum teratoma. The majority of teratoma is polypoid-shaped protruding into the rectal lumen similar to the present case. Many patients were presented with a prolapse of the tumor or hair, pain on defecation, and many had bloody stool (10). In one related case in the literature, the presenting complaint was only constipation (11). However, our case was presented with intermittent constipation and diarrhea with abdominal pain marked as IBS on two outpatient visits. The most commonplace of tumor development was the anterior wall of the rectum. However, a few cases reported that the tumor arose from the posterior and occasionally lateral wall (12). Endoscopic ultrasonography plays an essential role in treating rectal lesions. It is often difficult to distinguish between primary and secondary rectal teratomas. The presence of a welldefined pedicle may demonstrate that its origin is from a rectum, and a primary rectal teratoma is completely covered by squamous epithelium. In contrast, ovarian teratoma has squamous epithelium as one component in the form of cysts inside the tumor. After six months, the CT scan represented that both of the ovaries were free of any lesions.
In summary, we presented a case of primary mature teratoma of the rectum, which was found to be similar to IBS and was successfully treated with surgical resection. It is commonly benign but may turn malignant. Table 1 presents the results of the patient's physical examination, along with hematologic and biochemistry tests.