- Email: [email protected]
Retrorectal Tumors
R e t ro re c t a l Tu m o r s Kelli Bullard Dunn,
MD*
KEYWORDS Retrorectal Presacral tumor Congenital cyst Chordoma
Tumors occurring in the retrorectal (presacral) space are rare. The true incidence of these tumors is unknown, but several retrospective series suggest that between 1 and 6 patients are diagnosed annually in major referral centers.1–5 One study found that retrorectal tumors represented about 1 in 40,000 hospital admissions.6 The retrorectal space contains multiple embryologic remnants derived from various 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. Retrorectal tumors often go undetected because of nonspecific symptoms. Most benign lesions are asymptomatic. Pain or obstruction occur occasionally. Other symptoms, such as postural headache (associated with anterior meningocele), are considerably rarer.6 Most of these lesions are palpable on digital rectal examination. Once detected, radiologic evaluation (especially pelvic magnetic resonance imaging [MRI]) is invaluable in surgical planning. Most retrorectal tumors ultimately require surgical resection (without preoperative biopsy), although biopsy can be considered for unresectable lesions or in patients who will not tolerate surgery.
ANATOMY
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 fascia (Fig. 1). 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 In addition, the complexity of pelvic anatomy can make surgical management challenging.
Department of Surgical Oncology, Roswell Park Cancer Institute and the University at Buffalo, State University of New York, Elm and Carlton Streets, Buffalo, NY 14263, USA * Corresponding author. E-mail address: [email protected] Surg Clin N Am 90 (2010) 163–171 doi:10.1016/j.suc.2009.09.009 surgical.theclinics.com 0039-6109/09/$ – see front matter ª 2010 Elsevier Inc. All rights reserved.
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Fig. 1. The boundaries of the retrorectal (presacral) space are the rectum anteriorly, the presacral fascia posteriorly, the endopelvic fascia laterally (lateral ligaments), the posterior peritoneal reflection superiorly, and Waldeyer fascia inferiorly. (From Nicholls J, Dozios RR, editors. Surgery of the colon and rectum. Edinburgh: Churchill Livingstone, 1997; with permission.)
CONGENITAL LESIONS
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 cystic (developmental cysts, duplication cysts, and anterior meningoceles) and solid lesions (chordomas, teratomas, and adrenal rest tumors).2,6,8 DEVELOPMENTAL CYSTS
Developmental cysts constitute most congenital lesions and may arise from all 3 germ cell layers. These lesions have been reported to be more common in women than in men.6,8 Developmental cysts are further classified as dermoid and epidermoid cysts. Tailgut cysts are often classified as developmental cysts, but are probably more closely related to enterogenous duplication cysts. 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 various cutaneous appendages (dermoid), and they may communicate with the skin creating a postanal dimple (Fig. 2). These lesions have a high rate of infection (up to 30%),9 and infected cysts can be easily mistaken for perirectal abscess, pilonidal disease, or fistulae in ano. Recurrence after surgical therapy suggests that there may be an underlying congenital cyst.10 DUPLICATION CYSTS
Enterogenous cysts arise from the primitive gut. Sequestration of the hindgut during embryogenesis results in thin-walled, multilocular cysts lined by columnar epithelium.
Retrorectal Tumors
Fig. 2. Dermoid and epidermoid cysts may communicate with the skin forming a postanal dimple. Infected cysts, especially those that communicate with the skin, are often confused with pilonidal disease or fistulae in ano. (Courtesy of W Douglas Wong, MD, Memorial Sloan Kettering Cancer Institute, New York, NY.)
Tailgut cysts (retrorectal cystic hamartomas) are similar in origin, arising from a portion of the embryonic tail that fails to regress (Fig. 3).11 Rectal duplication cysts also occur and possess all components of the intestinal wall. Most of these lesions are benign, although rare malignant degeneration has been reported.12–15
Fig. 3. Sagittal MRI image of a large tailgut cyst. (Courtesy of W Douglas Wong, MD, Memorial Sloan Kettering Cancer Institute, New York, NY.)
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ANTERIOR MENINGOCELE
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 (Fig. 4). In addition to nonspecific symptoms, patients with anterior meningocele may present with headache; these headaches are often positional or related to changes in intra-abdominal 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 CHORDOMA
Chordomas arise from the notochord and are the most common malignant tumor of the retrorectal space.4 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%–50%).17 These tumors are slow-growing, invasive cancers that show characteristic bony destruction (Fig. 5). 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 TERATOMA
Teratomas are true neoplasms and contain tissue from each germ cell layer. They can be cystic or solid and often contain both components. Like developmental cysts,
Fig. 4. The ‘‘scimitar sign,’’ a unilateral sacral defect without bony destruction, is pathognomonic for anterior meningocele (Reprinted from Bou-Assaly W. AJR teaching file: child with chronic constipation. Am J Roentgenol 2007;189; with permission.)
Retrorectal Tumors
Fig. 5. Computed tomographic and MRI images of a chordoma demonstrating characteristic multilobular appearance and bony destruction. (Courtesy of W Douglas Wong, MD, Memorial Sloan Kettering Cancer Institute, New York, NY.)
teratomas are more common in female than in male patients. Many teratomas possess germ-cell elements that are capable of malignant degeneration, and up to 10% of retrorectal teratomas progress to cancer if left untreated.1 Teratomas are more common in children than in adults, but when found in adults, they are more likely to be malignant.7,19 Teratomas classically possess various tissue types, including respiratory, nervous system, and gastrointestinal structures. These lesions are usually tightly attached to the coccyx and resection requires en bloc coccygectomy.1
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).1
NEUROGENIC LESIONS
Neurogenic lesions typically arise from peripheral nerves and represent about 10% of retrorectal tumors. These tumors include neurofibromas and sarcomas, neurilemmomas, ependymomas, schwannomas, 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 seems to be good.1,6,8
OSSEOUS LESIONS
Osseous lesions also make up about 10% of retrorectal lesions and include osteomas, bone cysts, and neoplasms, such as osteogenic sarcoma, Ewing 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
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INFLAMMATORY LESIONS
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 or perineal sepsis can track into this space. Crohn disease and diverticulitis may also manifest with retrorectal inflammation. Finally, more uncommon inflammatory conditions (tuberculosis and granulomatous disease) have been reported in this area.1,5 MISCELLANEOUS
Miscellaneous lesions in the retrorectal space include a wide variety of benign and malignant masses (Box 1). Treatment and prognosis are usually related to the natural history of the underlying disease.21 Clinical Presentation and Evaluation
Symptoms of retrorectal tumors are often nonspecific and are related to the location and size of the lesion. Most benign cystic lesions are asymptomatic and are discovered on routine rectal examination.6 Some authors have suggested that the observed higher incidence of these lesions in women may be related to selection bias resulting from annual pelvic and rectal examinations.1 Infection or bony invasion may produce pain (lower back, rectal/pelvic, or lower extremity). Postural headache or headache associated with changes in intra-abdominal pressure, as occurs with defecation, are suggestive of anterior meningocele. Large masses (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.22 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. Flexible sigmoidoscopy or colonoscopy are useful for detecting full-thickness rectal involvement. Plain radiographs are often obtained and are occasionally useful; for example, the ‘‘scimitar sign’’ is pathognomonic for anterior meningocele. Computed tomographic scans have been used extensively, but with recent advances in technology, pelvic MRI is emerging as the most sensitive and specific imaging study. A myelogram is occasionally necessary if there is central nervous system involvement.7 The role of biopsy is a critical, and often misunderstood, aspect of evaluating retrorectal lesions. In general, biopsy is almost never indicated. For resectable lesions, surgical resection is the best diagnostic and therapeutic option.1 For cystic lesions, needle biopsy or aspiration may result in infection; in meningocele, this can cause meningitis. Biopsy of malignant lesions (especially chordoma) can result in tumor spread and seeding of the needle track.4,6 If a patient has undergone needle biopsy of a chordoma, it is important to excise the biopsy track at the time of resection.1 Unresectable tumors are the main indication for biopsy to direct nonoperative therapy. Biopsy can also be helpful in patients with significant medical comorbidity that precludes pelvic surgery. Occasionally, to exclude metastatic disease, biopsy may be appropriate for a patient with a history of another malignancy. Treatment
For patients who are medically fit for an operation and in whom the lesion seems resectable, treatment of retrorectal lesions is almost always surgical resection. The approach depends on the nature and location of the lesion. Lesions that do not extend
Retrorectal Tumors
Box 1 Classification of retrorectal masses Congenital Developmental cyst Epidermoid cyst Dermoid cyst Teratoma Chordoma Anterior meningocele Rectal duplication Adrenal rest tumors Neurogenic Neurofibroma Neurolemmoma Ependymoma Ganglioneuroma Neurofibrosarcoma Osseous Osteoma Osteogenic sarcoma Sacral bone cyst Ewing tumor Giant cell tumor Chondromyxosarcoma Inflammatory Granuloma Perineal abscess Pelvirectal abscess Fistula Chorionic granulomas Miscellaneous Metastatic disease Lymphangioma Desmoid tumor Leiomyoma Fibrosarcoma Endothelioma
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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 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 Although experience with minimally invasive approaches to resection of these tumors is limited, laparoscopic resection and transanal endoscopic microsurgery have been reported.24–27 The reader is directed to a surgical textbook or atlas for a more detailed description of these operations. Medical or radiation therapy are fairly ineffective in treating primary retrorectal lesions. Malignancies in this location are frequently resistant to chemotherapy and radiation. Radiation is occasionally useful for palliation. In contrast, metastases to this area (especially from colorectal carcinoma) often respond to combination chemoradiation therapy. Long-term outcome after resection of a retrorectal lesion depends on 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. Teratomas often involve the coccyx, and in this setting, coccygectomy can reduce the risk of local recurrence. 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 long-term survival are highly variable, ranging from 43% to 75% 5-year survival and 9% to 35% 10-year survival.6,17–20 Other malignancies tend to have poorer prognosis. SUMMARY
Retrorectal tumors are rare and heterogeneous. Signs and symptoms are often vague and nonspecific, although almost all lesions are palpable on digital rectal examination. In most cases, surgical resection will be required, and radiologic imaging (especially MRI) can be critical for surgical planning. Biopsy should be avoided unless the lesion seems unresectable. Finally, resection of retrorectal tumors can be complicated and the use of a multidisciplinary team is invaluable. REFERENCES
1. Hobson KG, Ghaemmaghami V, Roe JP, et al. Tumors of the retrorectal space. Dis Colon Rectum 2005;48(10):1964–74. 2. Uhlig BE, Johnson RL. Presacral tumors and cysts in adults. Dis Colon Rectum 1975;18(7):581–9. 3. Johnson WR. Postrectal neoplasms and cysts. Aust N Z J Surg 1980;50(2):163–6. 4. Cody HS 3rd, Marcove RC, Quan SH. Malignant retrorectal tumors: 28 years’ experience at Memorial Sloan-Kettering Cancer Center. Dis Colon Rectum 1981;24(7):501–6. 5. Freier DT, Stanley JC, Thompson NW. Retrorectal tumors in adults. Surg Gynecol Obstet 1971;132(4):681–6. 6. Jao SW, Beart RW Jr, Spencer RJ, et al. Retrorectal tumors. Mayo Clinic experience, 1960–1979. Dis Colon Rectum 1985;28(9):644–52. 7. Bullard Dunn K, Rothenberger D. Colon, rectum, and anus. In: Brunicardi C, editor. Schwartz’s principles of surgery. 9th edition. New York: McGraw Hill, in press.
Retrorectal Tumors
8. Stewart RJ, Humphreys WG, Parks TG. The presentation and management of presacral tumours. Br J Surg 1986;73(2):153–5. 9. Abel ME, Nelson R, Prasad ML, et al. Parasacrococcygeal approach for the resection of retrorectal developmental cysts. Dis Colon Rectum 1985;28(11): 855–8. 10. Singer MA, Cintron JR, Martz JE, et al. Retrorectal cyst: a rare tumor frequently misdiagnosed. J Am Coll Surg 2003;196(6):880–6. 11. Hjermstad BM, Helwig EB. Tailgut cysts. Report of 53 cases. Am J Clin Pathol 1988;89(2):139–47. 12. Springall RG, Griffiths JD. Malignant change in rectal duplication. J R Soc Med 1990;83(3):185–7. 13. Krivokapic Z, Dimitrijevic I, Barisic G, et al. Adenosquamous carcinoma arising within a retrorectal tailgut cyst: report of a case. World J Gastroenterol 2005; 11(39):6225–7. 14. Tampi C, Lotwala V, Lakdawala M, et al. Retrorectal cyst hamartoma (tailgut cyst) with malignant transformation. Gynecol Oncol 2007;105(1):266–8. 15. Shivnani AT, Small W Jr, Benson A 3rd, et al. Adenocarcinoma arising in rectal duplication cyst: case report and review of the literature. Am Surg 2004;70(11): 1007–9. 16. Williams B. Cerebrospinal fluid pressure changes in response to coughing. Brain 1976;99(2):331–46. 17. McMaster ML, Goldstein AM, Bromley CM, et al. Chordoma: incidence and survival patterns in the United States, 1973–1995. Cancer Causes Control 2001;12(1):1–11. 18. Bergh P, Kindblom LG, Gunterberg B, et al. Prognostic factors in chordoma of the sacrum and mobile spine: a study of 39 patients. Cancer 2000;88(9):2122–34. 19. Finne CO. Presacral tumors and cysts. In: Cameron J, editor. Current surgical therapy. 3rd edition. Toronto: BC Decker; 1989. p. 736–43. 20. Miyahara M, Saito T, Nakashima K, et al. Sacral chordoma developing two years after low anterior resection for rectal cancer. Surg Today 1993;23(2):144–8. 21. Gordon P. Retrorectal tumors. In: Gordon P, Nivatvongs S, editors. Principles and practice of surgery for the colon, rectum, and anus. St Louis (MO): Quality Medical Publishing, Inc; 1999. p. 427–45. 22. Sobrado CW, Mester M, Simonsen OS, et al. Retrorectal tumors complicating pregnancy. Report of two cases. Dis Colon Rectum 1996;39(10):1176–9. 23. Bohm B, Milsom JW, Fazio VW, et al. Our approach to the management of congenital presacral tumors in adults. Int J Colorectal Dis 1993;8(3):134–8. 24. Gunkova P, Martinek L, Dostalik J, et al. Laparoscopic approach to retrorectal cyst. World J Gastroenterol 2008;14(42):6581–3. 25. Chen Y, Xu H, Li Y, et al. Laparoscopic resection of presacral teratomas. J Minim Invasive Gynecol 2008;15(5):649–51. 26. Palanivelu C, Rangarajan M, Senthilkumar R, et al. Laparoscopic and perineal excision of an infected ‘‘dumb-bell’’ shaped retrorectal epidermoid cyst. J Laparoendosc Adv Surg Tech A 2008;18(1):88–92. 27. Zoller S, Joos A, Dinter D, et al. Retrorectal tumors: excision by transanal endoscopic microsurgery. Rev Esp Enferm Dig 2007;99(9):547–50.
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MD*
KEYWORDS Retrorectal Presacral tumor Congenital cyst Chordoma
Tumors occurring in the retrorectal (presacral) space are rare. The true incidence of these tumors is unknown, but several retrospective series suggest that between 1 and 6 patients are diagnosed annually in major referral centers.1–5 One study found that retrorectal tumors represented about 1 in 40,000 hospital admissions.6 The retrorectal space contains multiple embryologic remnants derived from various 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. Retrorectal tumors often go undetected because of nonspecific symptoms. Most benign lesions are asymptomatic. Pain or obstruction occur occasionally. Other symptoms, such as postural headache (associated with anterior meningocele), are considerably rarer.6 Most of these lesions are palpable on digital rectal examination. Once detected, radiologic evaluation (especially pelvic magnetic resonance imaging [MRI]) is invaluable in surgical planning. Most retrorectal tumors ultimately require surgical resection (without preoperative biopsy), although biopsy can be considered for unresectable lesions or in patients who will not tolerate surgery.
ANATOMY
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 fascia (Fig. 1). 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 In addition, the complexity of pelvic anatomy can make surgical management challenging.
Department of Surgical Oncology, Roswell Park Cancer Institute and the University at Buffalo, State University of New York, Elm and Carlton Streets, Buffalo, NY 14263, USA * Corresponding author. E-mail address: [email protected] Surg Clin N Am 90 (2010) 163–171 doi:10.1016/j.suc.2009.09.009 surgical.theclinics.com 0039-6109/09/$ – see front matter ª 2010 Elsevier Inc. All rights reserved.
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Fig. 1. The boundaries of the retrorectal (presacral) space are the rectum anteriorly, the presacral fascia posteriorly, the endopelvic fascia laterally (lateral ligaments), the posterior peritoneal reflection superiorly, and Waldeyer fascia inferiorly. (From Nicholls J, Dozios RR, editors. Surgery of the colon and rectum. Edinburgh: Churchill Livingstone, 1997; with permission.)
CONGENITAL LESIONS
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 cystic (developmental cysts, duplication cysts, and anterior meningoceles) and solid lesions (chordomas, teratomas, and adrenal rest tumors).2,6,8 DEVELOPMENTAL CYSTS
Developmental cysts constitute most congenital lesions and may arise from all 3 germ cell layers. These lesions have been reported to be more common in women than in men.6,8 Developmental cysts are further classified as dermoid and epidermoid cysts. Tailgut cysts are often classified as developmental cysts, but are probably more closely related to enterogenous duplication cysts. 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 various cutaneous appendages (dermoid), and they may communicate with the skin creating a postanal dimple (Fig. 2). These lesions have a high rate of infection (up to 30%),9 and infected cysts can be easily mistaken for perirectal abscess, pilonidal disease, or fistulae in ano. Recurrence after surgical therapy suggests that there may be an underlying congenital cyst.10 DUPLICATION CYSTS
Enterogenous cysts arise from the primitive gut. Sequestration of the hindgut during embryogenesis results in thin-walled, multilocular cysts lined by columnar epithelium.
Retrorectal Tumors
Fig. 2. Dermoid and epidermoid cysts may communicate with the skin forming a postanal dimple. Infected cysts, especially those that communicate with the skin, are often confused with pilonidal disease or fistulae in ano. (Courtesy of W Douglas Wong, MD, Memorial Sloan Kettering Cancer Institute, New York, NY.)
Tailgut cysts (retrorectal cystic hamartomas) are similar in origin, arising from a portion of the embryonic tail that fails to regress (Fig. 3).11 Rectal duplication cysts also occur and possess all components of the intestinal wall. Most of these lesions are benign, although rare malignant degeneration has been reported.12–15
Fig. 3. Sagittal MRI image of a large tailgut cyst. (Courtesy of W Douglas Wong, MD, Memorial Sloan Kettering Cancer Institute, New York, NY.)
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ANTERIOR MENINGOCELE
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 (Fig. 4). In addition to nonspecific symptoms, patients with anterior meningocele may present with headache; these headaches are often positional or related to changes in intra-abdominal 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 CHORDOMA
Chordomas arise from the notochord and are the most common malignant tumor of the retrorectal space.4 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%–50%).17 These tumors are slow-growing, invasive cancers that show characteristic bony destruction (Fig. 5). 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 TERATOMA
Teratomas are true neoplasms and contain tissue from each germ cell layer. They can be cystic or solid and often contain both components. Like developmental cysts,
Fig. 4. The ‘‘scimitar sign,’’ a unilateral sacral defect without bony destruction, is pathognomonic for anterior meningocele (Reprinted from Bou-Assaly W. AJR teaching file: child with chronic constipation. Am J Roentgenol 2007;189; with permission.)
Retrorectal Tumors
Fig. 5. Computed tomographic and MRI images of a chordoma demonstrating characteristic multilobular appearance and bony destruction. (Courtesy of W Douglas Wong, MD, Memorial Sloan Kettering Cancer Institute, New York, NY.)
teratomas are more common in female than in male patients. Many teratomas possess germ-cell elements that are capable of malignant degeneration, and up to 10% of retrorectal teratomas progress to cancer if left untreated.1 Teratomas are more common in children than in adults, but when found in adults, they are more likely to be malignant.7,19 Teratomas classically possess various tissue types, including respiratory, nervous system, and gastrointestinal structures. These lesions are usually tightly attached to the coccyx and resection requires en bloc coccygectomy.1
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).1
NEUROGENIC LESIONS
Neurogenic lesions typically arise from peripheral nerves and represent about 10% of retrorectal tumors. These tumors include neurofibromas and sarcomas, neurilemmomas, ependymomas, schwannomas, 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 seems to be good.1,6,8
OSSEOUS LESIONS
Osseous lesions also make up about 10% of retrorectal lesions and include osteomas, bone cysts, and neoplasms, such as osteogenic sarcoma, Ewing 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
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INFLAMMATORY LESIONS
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 or perineal sepsis can track into this space. Crohn disease and diverticulitis may also manifest with retrorectal inflammation. Finally, more uncommon inflammatory conditions (tuberculosis and granulomatous disease) have been reported in this area.1,5 MISCELLANEOUS
Miscellaneous lesions in the retrorectal space include a wide variety of benign and malignant masses (Box 1). Treatment and prognosis are usually related to the natural history of the underlying disease.21 Clinical Presentation and Evaluation
Symptoms of retrorectal tumors are often nonspecific and are related to the location and size of the lesion. Most benign cystic lesions are asymptomatic and are discovered on routine rectal examination.6 Some authors have suggested that the observed higher incidence of these lesions in women may be related to selection bias resulting from annual pelvic and rectal examinations.1 Infection or bony invasion may produce pain (lower back, rectal/pelvic, or lower extremity). Postural headache or headache associated with changes in intra-abdominal pressure, as occurs with defecation, are suggestive of anterior meningocele. Large masses (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.22 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. Flexible sigmoidoscopy or colonoscopy are useful for detecting full-thickness rectal involvement. Plain radiographs are often obtained and are occasionally useful; for example, the ‘‘scimitar sign’’ is pathognomonic for anterior meningocele. Computed tomographic scans have been used extensively, but with recent advances in technology, pelvic MRI is emerging as the most sensitive and specific imaging study. A myelogram is occasionally necessary if there is central nervous system involvement.7 The role of biopsy is a critical, and often misunderstood, aspect of evaluating retrorectal lesions. In general, biopsy is almost never indicated. For resectable lesions, surgical resection is the best diagnostic and therapeutic option.1 For cystic lesions, needle biopsy or aspiration may result in infection; in meningocele, this can cause meningitis. Biopsy of malignant lesions (especially chordoma) can result in tumor spread and seeding of the needle track.4,6 If a patient has undergone needle biopsy of a chordoma, it is important to excise the biopsy track at the time of resection.1 Unresectable tumors are the main indication for biopsy to direct nonoperative therapy. Biopsy can also be helpful in patients with significant medical comorbidity that precludes pelvic surgery. Occasionally, to exclude metastatic disease, biopsy may be appropriate for a patient with a history of another malignancy. Treatment
For patients who are medically fit for an operation and in whom the lesion seems resectable, treatment of retrorectal lesions is almost always surgical resection. The approach depends on the nature and location of the lesion. Lesions that do not extend
Retrorectal Tumors
Box 1 Classification of retrorectal masses Congenital Developmental cyst Epidermoid cyst Dermoid cyst Teratoma Chordoma Anterior meningocele Rectal duplication Adrenal rest tumors Neurogenic Neurofibroma Neurolemmoma Ependymoma Ganglioneuroma Neurofibrosarcoma Osseous Osteoma Osteogenic sarcoma Sacral bone cyst Ewing tumor Giant cell tumor Chondromyxosarcoma Inflammatory Granuloma Perineal abscess Pelvirectal abscess Fistula Chorionic granulomas Miscellaneous Metastatic disease Lymphangioma Desmoid tumor Leiomyoma Fibrosarcoma Endothelioma
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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 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 Although experience with minimally invasive approaches to resection of these tumors is limited, laparoscopic resection and transanal endoscopic microsurgery have been reported.24–27 The reader is directed to a surgical textbook or atlas for a more detailed description of these operations. Medical or radiation therapy are fairly ineffective in treating primary retrorectal lesions. Malignancies in this location are frequently resistant to chemotherapy and radiation. Radiation is occasionally useful for palliation. In contrast, metastases to this area (especially from colorectal carcinoma) often respond to combination chemoradiation therapy. Long-term outcome after resection of a retrorectal lesion depends on 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. Teratomas often involve the coccyx, and in this setting, coccygectomy can reduce the risk of local recurrence. 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 long-term survival are highly variable, ranging from 43% to 75% 5-year survival and 9% to 35% 10-year survival.6,17–20 Other malignancies tend to have poorer prognosis. SUMMARY
Retrorectal tumors are rare and heterogeneous. Signs and symptoms are often vague and nonspecific, although almost all lesions are palpable on digital rectal examination. In most cases, surgical resection will be required, and radiologic imaging (especially MRI) can be critical for surgical planning. Biopsy should be avoided unless the lesion seems unresectable. Finally, resection of retrorectal tumors can be complicated and the use of a multidisciplinary team is invaluable. REFERENCES
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