Kelli Bullard Dunn, M.D., F.A.C.S., F.A.S.C.R.S
Department of Surgery and Surgical Oncology
Roswell Park Cancer Institute and the
University at Buffalo/State University of New York
Tumors occurring in the retrorectal (presacral) space are rare. The true incidence of these tumors is unknown, but several retrospective series suggest that between one and six patients will be diagnosed annually in major referral centers.[1-5] One study found that retrorectal tumors represented about one in 40,000 hospital admissions. The retrorectal space contains multiple embryologic remnants derived from a variety of tissues, and tumors that develop in this space are both grossly and histologically heterogeneous. Most lesions are benign, but malignant neoplasms are not uncommon. Malignancy is more common in the pediatric population than in adults, and solid lesions are more likely to be malignant than are cystic lesions. Almost all retrorectal tumors require surgical management.
The retrorectal or presacral space lies between the upper two-thirds of the rectum and the sacrum above the rectosacral fascia. It is bound by the rectum anteriorly, the presacral fascia posteriorly, and the endopelvic fascia laterally (lateral ligaments). The superior border of the space is the posterior peritoneal reflection of the rectum and the inferior border is Waldeyer’s fascia. This region contains structures derived from embryonic neuroectoderm, notochord, and hindgut, and many tumors arise from embryonic remnants. As a result, retrorectal tumors are clinically diverse.[1, 7]
Congenital lesions are most common, comprising approximately two-thirds of retrorectal tumors. These lesions are thought to arise from the remnants of embryonic tissues and include both cystic (developmental cysts, duplication cysts, anterior meningoceles) and solid lesions (chordomas, teratomas, adrenal rest tumors). [2, 6, 8]
Developmental cysts constitute the majority of congenital lesions and may arise from all three germ cell layers. These lesions are considerably more common in women than in men.
Dermoid and epidermoid cysts:
Dermoid and epidermoid cysts are benign lesions that arise from the ectoderm. These cysts are lined with squamous epithelium (epidermoid) or a combination of squamous epithelium and a variety of cutaneous appendages. These cysts may communicate with the skin creating a postanal dimple and have a high rate of infection (up to 30%). Infected cysts (especially those that communicate with the skin) can be easily mistaken for pilonidal disease or fistulae-in-ano. Recurrence after surgical therapy may suggest the presence of an underlying congenital cyst.
Enterogenous cysts arise from the primitive gut. Sequestration of the hindgut during embryogenesis results in thin walled, multilocular cysts lined by columnar epithelium. Tailgut cysts (retrorectal cyst-hamartomas) are similar in origin, arising from a portion of the embryonic tail that fails to regress. Rectal duplication cysts also occur and possess all components of the intestinal wall. The majority of these lesions are benign, although rare malignant degeneration has been reported.[12-15]
Anterior meningocele and myelomeningocele arise from herniation of the dural sac through a defect in the anterior sacrum. This unilateral sacral defect results in the pathognomonic “scimitar sign” (sacrum with a rounded, concave border without any bony destruction) on plain radiographs. In addition to nonspecific symptoms, patients with anterior meningocele may present with headache; these headaches are often positional and/or related to changes in intraabdominal pressure or defecation.[1, 6, 16] Aspiration of an anterior meningocele should be strictly avoided because of the risk of causing meningitis.[1, 7, 10]
Chordomas arise from the notochord and are the most common malignant tumor of the retrorectal space. Chordomas frequently present with pain, and are thought to be more common in men. Chordomas can occur anywhere in the spine, but the most common single site is the sacrococcygeal region (30% to 50%). These tumors are slow-growing, invasive cancers that show characteristic bony destruction. Radical resection offers the best hope for cure, but local recurrence rates are high, and 10 year survival is only 9% to 35%.[6, 18-20]
Teratomas are true neoplasms and contain tissue from each germ cell layer. They can be either cystic or solid, and often contain both components. Like developmental cysts, teratomas are more common in female patients than in male patients. Many teratomas possess germ-cell elements that are capable of malignant degeneration, and up to ten percent of retrorectal teratomas will progress to cancer if left untreated. Teratomas are more common in children than in adults, but when found in adults, are more likely to be malignant.[7, 19] Teratomas classically possess a variety of tissue types, including respiratory, nervous system, and gastrointestinal structures. These lesions are usually tightly attached to the coccyx and resection requires en bloc coccygectomy.
Adrenal rest tumor:
Adrenal rest tumors are extremely rare, and, although congenital in nature, are often classified as “miscellaneous”. They are treated as ectopic adrenal tumors (including pheochromocytoma) .
Inflammatory lesions may be solid or cystic (abscess) and usually represent extensions of infection either in the perirectal space or in the abdomen (infected congenital cysts are not considered primarily inflammatory). Foreign body granulomas may result from barium or suture material. Pelvic and/or perineal sepsis can track into this space. Crohn’s disease and diverticulitis may also manifest with retrorectal inflammation. Finally, more uncommon inflammatory conditions (tuberculosis, granulomatous disease) have been reported in this area.[1, 5]
Neurogenic lesions typically arise from peripheral nerves and represent about 10% of retrorectal tumors. These tumors include neurofibromas and sarcomas, neurilemomas, ependymomas, and ganglioneuromas. Ependymomas are most common. Pain and neurologic dysfunction are often presenting symptoms and are related to the route of the involved nerve. Radical resection (often resulting in significant disability) is usually required, but overall survival appears to be good.[1, 6, 8]
Osseous lesions also make up about 10% of retrorectal lesions and include osteomas and bone cysts, as well as neoplasms such as osteogenic sarcoma, Ewing's tumor, chondromyxosarcoma, and giant cell tumors. Although benign lesions in this region are often amenable to radical resection, local recurrence can be problematic. Malignant lesions in this location are typically advanced and have poor prognosis.[1, 5, 6, 21]
Miscellaneous lesions in the retrorectal space include a wide variety of both benign and malignant masses (Table 1). Treatment and prognosis are usually related to the natural history of the underlying disease.
Clinical presentation and evaluation:
Symptoms of retrorectal tumors are often nonspecific and are related the location and size of the lesion. The majority of benign cystic lesions are asymptomatic and are discovered on routine rectal examination. Infection and/or bony invasion may produce pain (lower back, rectal/pelvic, or lower extremity). Postural headache or headache associated with changes in intraabdominal pressure are suggestive of anterior meningocele. Large masses (either cystic or solid) may cause obstruction, leading to constipation, straining, or overflow incontinence. Rarely, large neoplasms can cause obstructed labor and lead to life-threatening dystocia.
Evaluation begins with a careful rectal examination. Almost all retrorectal masses can be palpated and the location, size, and proximal extent of the tumor are critical for surgical planning. Plain x-rays are often obtained and occasionally useful; for example, the “scimitar sign” is pathognomonic for anterior meningocele. CT scans have been used extensively, but with recent advances in technology, pelvic MRI is emerging as the most sensitive and specific imaging study. Myelogram is occasionally necessary if there is central nervous system involvement.
One critical, and often misunderstood, component of evaluating retrorectal lesions involves the role of biopsy. In general, biopsy is almost never indicated. For resectable lesions, surgical resection is both the best diagnostic and therapeutic option. For cystic lesions, needle biopsy or aspiration may result in infection; in meningocele this may cause meningitis. Biopsy of malignant lesions (especially chordoma) can result in tumor spread and seeding of the needle track. If a patient has undergone needle biopsy of a chordoma, it is important to excise the biopsy track at the time of resection. The main indication for biopsy is in patients with unresectable tumors in order to direct nonoperative therapy.
For patients who are medically fit for an operation, treatment of retrorectal lesions is almost always surgical resection. The approach depends upon the nature of the lesion and upon its location. Lesions that do not extend below S4 (high lesions) can be resected transabdominally (anterior approach). Lower lesions can be resected transsacrally (posterior approach). If the upper extent of the lesion can be palpated on rectal examination, it is likely to be resectable transsacrally. Larger lesions or those in an intermediate position may require a combined abdominal and sacral operation. Invasion of the rectum requires rectal resection. Sacrococcygeal invasion requires coccygectomy and/or sacrectomy. In these complicated cases, a multidisciplinary team, including a colon and rectal surgeon, neurosurgeon or orthopedic surgeon, and plastic surgeon is critical. [1, 9, 23] The reader is directed to a surgical textbook and/or atlas for a more detailed description of these operations.
Medical and/or radiation therapy are relatively ineffective in treating retrorectal lesions. Malignancies in this location are frequently resistant to chemotherapy and radiation. Radiation is occasionally useful for palliation.
Longterm outcome after resection of a retrorectal lesion depends upon the type of tumor and on adequate resection at the initial operation. For benign lesions, survival is excellent, but local recurrence is common. Recurrent lesions can often be resected for cure. Prognosis after resection of malignant lesions is variable and reflects the biology of the underlying tumor. For chordoma, local recurrence is common, and reports of longterm survival are highly variable, ranging from 43% to 75% five year survival and 9% to 35% ten year survival [6, 18-20]  Other malignancies tend to have poorer prognosis.
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Table 1. Classification of retrorectal masses.
Adrenal rest tumors
Sacral bone cyst
Giant cell tumor