Intestinal-type Adenocarcinoma Possibly Arising from a Remnant of the Rectovaginal Fistula Tract Formed after Intermediate-level Imperforate Anus Repair

Abstract

A 45-year-old Japanese woman, gravid 0, was referred to our hospital with a tentative diagnosis of primary vaginal adenocarcinoma. She complained of mucinous vaginal discharge, intermittent genital bleeding and long-term anal discomfort. She had a history of surgery for intermediate-level imperforate anus in her neonatal period, but we could not get any detailed information about her clinical history because of the loss of her parents in childhood. Pelvic examination revealed an exophytic hemorrhagic tumor filling the vagina. The tumor did not extend into the uterus, and no parametrial tissues or other pelvic organs were involved. She had experienced anal prolapse, which had been recognized about 25 years previously (Fig. 1). Barium enema study exhibited no abnormal findings. Pelvic magnetic resonance imaging studies showed a demarcated tumor 8 4 3 cm in size in a cavity just behind the vagina (Fig. 2, white arrowheads). The tumor filled the vaginal cavity, reaching the introitus (Fig. 2, closed star), but did not contact the rectum (Fig. 2, black asterisk). Positron emission tomography-computed tomography (PET-CT) studies depicted no distant metastasis. Serum carcinoembryonic antigen and sialyl Tn antigen levels were elevated as high as 6.4 ng/ml and 140 U/ml, respectively. The histopathological diagnosis of biopsy specimens was adenocarcinoma. Immunohistochemical staining demonstrated that the tumor tissues were positive for CK7 and CK20. With the preoperative diagnosis of bulky primary adenocarcinoma of the vagina with FIGO stage I and severe anal prolapse, the patient underwent total pelvic exenteration followed by ileal conduit and permanent colostomy. We adopted this procedure including radical hysterectomy with extended total vaginectomy, cystourethrectomy and pelvic lymphadenectomy, firstly, because there is no well-established alternative or adjuvant therapy for vaginal adenocarcinoma and, secondly, because radical hysterectomy with extended total vaginectomy or posterior exenteration frequently denervates the urinary bladder resulting in severe voiding dysfunction. Histopathological diagnosis of the tumor was intestinal-type adenocarcinoma with invasion into the vagina and pelvic adipose tissue. The excisional margin was negative. The tumor was considered to have originated from the intestinal epithelium overlaying a cavity located behind the vagina. The cavity was partly surrounded by muscle layers similar to those of the intestine (Fig. 3). Therefore, we concluded that the tumor had arisen from a remnant of the rectovaginal fistula tract formed 45 years previously after the intermediate-level imperforate anus repair. PET-CT 1 year after the surgery revealed multiple lung metastases. She has been undergoing systemic chemotherapy since then for about 3 years.