Tailgut Cyst--A Rare Retrorectal Tumor: Report
of a Case and Review*
PhiLip R. CAROPRESO, M.D.,'~ PAUL A. WENGERT, JR., M.D., + HENRY E. MILFORD, M . D . w
From the Polyclinic Hospital, Harrisburg, Pennsylvania
T U M O R S O[ t h e retrorectal space are rare in adults, frequently unrecognized, misdiagnosed, and mistreated. Tailgut cysts are infrequently encountered. Only ten cases are reported in the literature. Another case fulfilling the anatomic and histologic criteria is presented. T h e anatomy of the retrorectal space is described and the embryology of tailgut cysts is discussed. T h e purpose of this paper is to review the information on this unusttal lesion, thereby aiding earlier recognition, diagnosis, and treatment.
Report of a Case A 30-year-old white w o m a n was admitted to the Polyclinic Hospital with a chief complaint of a mass in her rectum. T h e mass was discovered on a routine physical e x a m i n a t i o n by h e r internist. T h e patient was free of symptoms a n d denied changing bowel habits, diarrhea, constipation, melena, hematochezia, or m u c u s per rectum. She h a d no tenesmus a n d no rectal incontinence. She h a d no anorexia, weight loss or constitutional symptoms. A complete system review was negative. A pre-admission b a r i u m - e n e m a study disclosed no abnormality. Past medical history revealed that the patient h a d previously been hospitalized for right mastoidectomy a n d cholecystectomy. She h a d h a d two additional admissions for vaginal deliveries of two n o r m a l full-term pregnancies. T h e presence of a rectal mass was not reported on any of the prior hospitalization records. Physical e x a m i n a t i o n revealed that the patient was h e a l t h y and in no pain or discomfort. T h e entire e x a m i n a t i o n disclosed no a b n o r m a l i t y except
FIc. 1. Sagittal section t h r o u g h the pelvis, showing the a n a t o m y of the retrorectal space containing a tailgut cyst. in the rectum. On digital e x a m i n a t i o n a smooth, r o u n d mass, a p p r o x i m a t e l y 2 • 1.5 cm in size, was palpable on the posterior rectal wall. T h e lesion was located a p p r o x i m a t e l y 6 cm from the anal verge. It was firm a n d partially fixed in relation to the coccyx and perirectal tissues. T h e rectal mucosa a n d entire rectal wall seemed to glide over the mass on palpation. T h e r e was no edema, ulceration, or other irregularity of rectal mucosa overlying the lesion. Sigmoidoscopy to 25 cm showed no abnormality except the bulging mass on the rectal wall as described. Results of laboratory evaluations, i n c l u d i n g urinalysis, a n d SMA 6 a n d SMA 12 studies, were within n o r m a l limits. T h e hematocrit was 41.1 per cent and the h e m o g l o b i n was t3.4 g/100 ml. T h e chest x-ray and EKG were normal. T h e preoperative diagnosis was a mass in the rectum, probably representing an enteric duplica-
* Received for publication December 30, 1974. t Resident in Surgery. + Associate, D e p a r t m e n t of General Surgery. w Chief, D e p a r t m e n t of General Surgery. Address r e p r i n t requests to Dr. Caropreso: Resident in Surgery, Polyclinic Hospital, Harrisburg, Pennsylvania 17105.
597 Dis. Col. & Rect. October 1975
Volume 18 Number 7
598
C A R O P R E S O , E T AL.
FIe. 2A.
Dis. Col. & Reef. October 197.5
Low-power magnification of the tailgut cyst in cross section.
tion cyst. After mechanical preparation of the bowel, u n d e r general anesthesia, the patient u n d e r went a transrectal excision of the mass. W i t h the patient in the dorsal lithotomy position, the r e c t u m was progressively dilated. T h e mass was dissected intact from the retrorectal space only after all layers of the posterior rectal wall h a d been incised. T h e incision was then closed in layers, using inter-
rupted sutures of 2-0 chromic catgut. Frozen-section e x a m i n a t i o n revealed no evidence of malignancy, b u t an i m m e d i a t e definitive diagnosis could n o t be made. T h e patient h a d a benign postoperative course, a n d was discharged on the t h i r d postoperative day. A patholog3/- consultation with the Armed Forces Institute of Pathology provided the diagnosis of a tailgut cyst, a benign a n d rare lesion.
Volume 18 Number 7
TAILGUT
CYSTS
599
Fro. 2B. High-power photomicrogwaph of the tailgut cyst wall, showing prominent histologic features of columnar epithelium and random bundles of smooth muscle and connective tissue. Comment
T h e retrorectal space is a potential area, developing only when the rectum is displaced anteriorly by a mass. Anteriorly, the space is b o u n d e d by the rectum. It is con-
fined posteriorly by the sacrum and coccyx. T h e levators ani and the coccygeal muscles are the inferior limits, and the peritoneal reflection is the superior boundary. Laterally, the iliac vessels and the ureters corn-
600
CAROPRESO, ET AL.
plete the margins of the space. Within this area are the branches of the sacral plexus, the middle hemorrhoidal and middle sacral vessels, and lymphatics 1, 3 (Fig. 1). Tumors, cysts, and fistulas can arise from caudal vestiges. In the h u m a n embryo, a true tail is maximally developed at the 8m m stage and has disappeared at 30-35-mm stage. Within this location, many organ systems, including the primitive gut, the urogenital tract, early skeletal system, vascular and lymphatic channels, and the neural tube develop. Anomalies originate from arrested degelopment, heterotopia, and/or failure of regression in any of these organ systems. T h e tailgut appears in the 3.5-mm embryo and disappears at the 8-mm stage. It is a tubular structure lined with two to four layers of stratified cuboidal epithelium. As a vestigial remnant, it fills with epithelial debris and mucus prior to its resolution. In order to identify a tumor of tailgut origin, it must be within the retrorectal space, have an intestinal type of epithelial lining, and have no definite muscular or serous coat. As seen in the photomicrographs (Fig. 2, A and B), the cyst wall has stratified columnar epithelium with some areas of mucus-producing colunmar epithelium. Indefinite, random bundles of smooth muscle and connective tissue are present. Amorphous granular material with desquamated epithelium is contained within the cyst. 2 T h e first case report of a tailgut cyst was in 1885. Since that time, approximately ten cases have been reported. 2 T h e n u m b e r of cases is only approximate because of poor documentation in some instances. While tailgut cysts are usually benign, there has been one case report of carincoma arising in a caudal vestige. Most tailgut cysts have been discovered as incidental findings. Careful digital rectal examination should
Dis. Col. & Rect. October 1975
be the first step in the diagnosis of tailgut cysts, followed by proctosigmoidoscopy. Roentgenographic studies should include lateral and anterior and posterior projections of the sacrum and coccyx. A bariumenema study can be of value in assessing the size of a tumor. Arteriography and venography may be used, if a vascular lesion is suspected. I It is extremely important to achieve an accurate preoperative diagnosis in order to avoid unnecessary surgical procedures, and to perform the correct operation through the proper operative approach. Complete surgical excision is the treatment of choice for all retrorectal tumors. Although small benign tumors, such as the tailgut cyst presented, can be removed satisfactorily transrectally or perirectally, an abdominosacral approach is recommended for lesions larger than 5 cm, regardless of the histologic type. All tumors in this area should be surgically removed to: 1) relieve any symptoms that may be present, 2) reduce the potential for infection in this closed space, and 3) rule out the presence of malignancy. Summary A case of a tailgut cyst is presented. This rare, benign tumor must be considered in the differential diagnosis of retrorectal tumors. T h e anatomy o f the retrorectal space is described and the embryology of a tailgut cyst briefly reviewed. T h e authors' purpose is to acquaint physicians and surgeons with the entity of tailgut cysts so that an earlier diagnosis can be made and the proper treatment effected. References I. Freier DT, Stanley JC, Thompson NW: Retrorectal tumors in adults. Surg Gynecol Obstet 132: 681, 1971 2. Gius JA, Stout AP; Perianal cysts of vestigial origin. Arch Surg 37: 268, 1938 3. Jackman RJ, Clark PL, Smith ND: Retrorectal tumors. JAMA 145: 956, 1951
of a Case and Review*
PhiLip R. CAROPRESO, M.D.,'~ PAUL A. WENGERT, JR., M.D., + HENRY E. MILFORD, M . D . w
From the Polyclinic Hospital, Harrisburg, Pennsylvania
T U M O R S O[ t h e retrorectal space are rare in adults, frequently unrecognized, misdiagnosed, and mistreated. Tailgut cysts are infrequently encountered. Only ten cases are reported in the literature. Another case fulfilling the anatomic and histologic criteria is presented. T h e anatomy of the retrorectal space is described and the embryology of tailgut cysts is discussed. T h e purpose of this paper is to review the information on this unusttal lesion, thereby aiding earlier recognition, diagnosis, and treatment.
Report of a Case A 30-year-old white w o m a n was admitted to the Polyclinic Hospital with a chief complaint of a mass in her rectum. T h e mass was discovered on a routine physical e x a m i n a t i o n by h e r internist. T h e patient was free of symptoms a n d denied changing bowel habits, diarrhea, constipation, melena, hematochezia, or m u c u s per rectum. She h a d no tenesmus a n d no rectal incontinence. She h a d no anorexia, weight loss or constitutional symptoms. A complete system review was negative. A pre-admission b a r i u m - e n e m a study disclosed no abnormality. Past medical history revealed that the patient h a d previously been hospitalized for right mastoidectomy a n d cholecystectomy. She h a d h a d two additional admissions for vaginal deliveries of two n o r m a l full-term pregnancies. T h e presence of a rectal mass was not reported on any of the prior hospitalization records. Physical e x a m i n a t i o n revealed that the patient was h e a l t h y and in no pain or discomfort. T h e entire e x a m i n a t i o n disclosed no a b n o r m a l i t y except
FIc. 1. Sagittal section t h r o u g h the pelvis, showing the a n a t o m y of the retrorectal space containing a tailgut cyst. in the rectum. On digital e x a m i n a t i o n a smooth, r o u n d mass, a p p r o x i m a t e l y 2 • 1.5 cm in size, was palpable on the posterior rectal wall. T h e lesion was located a p p r o x i m a t e l y 6 cm from the anal verge. It was firm a n d partially fixed in relation to the coccyx and perirectal tissues. T h e rectal mucosa a n d entire rectal wall seemed to glide over the mass on palpation. T h e r e was no edema, ulceration, or other irregularity of rectal mucosa overlying the lesion. Sigmoidoscopy to 25 cm showed no abnormality except the bulging mass on the rectal wall as described. Results of laboratory evaluations, i n c l u d i n g urinalysis, a n d SMA 6 a n d SMA 12 studies, were within n o r m a l limits. T h e hematocrit was 41.1 per cent and the h e m o g l o b i n was t3.4 g/100 ml. T h e chest x-ray and EKG were normal. T h e preoperative diagnosis was a mass in the rectum, probably representing an enteric duplica-
* Received for publication December 30, 1974. t Resident in Surgery. + Associate, D e p a r t m e n t of General Surgery. w Chief, D e p a r t m e n t of General Surgery. Address r e p r i n t requests to Dr. Caropreso: Resident in Surgery, Polyclinic Hospital, Harrisburg, Pennsylvania 17105.
597 Dis. Col. & Rect. October 1975
Volume 18 Number 7
598
C A R O P R E S O , E T AL.
FIe. 2A.
Dis. Col. & Reef. October 197.5
Low-power magnification of the tailgut cyst in cross section.
tion cyst. After mechanical preparation of the bowel, u n d e r general anesthesia, the patient u n d e r went a transrectal excision of the mass. W i t h the patient in the dorsal lithotomy position, the r e c t u m was progressively dilated. T h e mass was dissected intact from the retrorectal space only after all layers of the posterior rectal wall h a d been incised. T h e incision was then closed in layers, using inter-
rupted sutures of 2-0 chromic catgut. Frozen-section e x a m i n a t i o n revealed no evidence of malignancy, b u t an i m m e d i a t e definitive diagnosis could n o t be made. T h e patient h a d a benign postoperative course, a n d was discharged on the t h i r d postoperative day. A patholog3/- consultation with the Armed Forces Institute of Pathology provided the diagnosis of a tailgut cyst, a benign a n d rare lesion.
Volume 18 Number 7
TAILGUT
CYSTS
599
Fro. 2B. High-power photomicrogwaph of the tailgut cyst wall, showing prominent histologic features of columnar epithelium and random bundles of smooth muscle and connective tissue. Comment
T h e retrorectal space is a potential area, developing only when the rectum is displaced anteriorly by a mass. Anteriorly, the space is b o u n d e d by the rectum. It is con-
fined posteriorly by the sacrum and coccyx. T h e levators ani and the coccygeal muscles are the inferior limits, and the peritoneal reflection is the superior boundary. Laterally, the iliac vessels and the ureters corn-
600
CAROPRESO, ET AL.
plete the margins of the space. Within this area are the branches of the sacral plexus, the middle hemorrhoidal and middle sacral vessels, and lymphatics 1, 3 (Fig. 1). Tumors, cysts, and fistulas can arise from caudal vestiges. In the h u m a n embryo, a true tail is maximally developed at the 8m m stage and has disappeared at 30-35-mm stage. Within this location, many organ systems, including the primitive gut, the urogenital tract, early skeletal system, vascular and lymphatic channels, and the neural tube develop. Anomalies originate from arrested degelopment, heterotopia, and/or failure of regression in any of these organ systems. T h e tailgut appears in the 3.5-mm embryo and disappears at the 8-mm stage. It is a tubular structure lined with two to four layers of stratified cuboidal epithelium. As a vestigial remnant, it fills with epithelial debris and mucus prior to its resolution. In order to identify a tumor of tailgut origin, it must be within the retrorectal space, have an intestinal type of epithelial lining, and have no definite muscular or serous coat. As seen in the photomicrographs (Fig. 2, A and B), the cyst wall has stratified columnar epithelium with some areas of mucus-producing colunmar epithelium. Indefinite, random bundles of smooth muscle and connective tissue are present. Amorphous granular material with desquamated epithelium is contained within the cyst. 2 T h e first case report of a tailgut cyst was in 1885. Since that time, approximately ten cases have been reported. 2 T h e n u m b e r of cases is only approximate because of poor documentation in some instances. While tailgut cysts are usually benign, there has been one case report of carincoma arising in a caudal vestige. Most tailgut cysts have been discovered as incidental findings. Careful digital rectal examination should
Dis. Col. & Rect. October 1975
be the first step in the diagnosis of tailgut cysts, followed by proctosigmoidoscopy. Roentgenographic studies should include lateral and anterior and posterior projections of the sacrum and coccyx. A bariumenema study can be of value in assessing the size of a tumor. Arteriography and venography may be used, if a vascular lesion is suspected. I It is extremely important to achieve an accurate preoperative diagnosis in order to avoid unnecessary surgical procedures, and to perform the correct operation through the proper operative approach. Complete surgical excision is the treatment of choice for all retrorectal tumors. Although small benign tumors, such as the tailgut cyst presented, can be removed satisfactorily transrectally or perirectally, an abdominosacral approach is recommended for lesions larger than 5 cm, regardless of the histologic type. All tumors in this area should be surgically removed to: 1) relieve any symptoms that may be present, 2) reduce the potential for infection in this closed space, and 3) rule out the presence of malignancy. Summary A case of a tailgut cyst is presented. This rare, benign tumor must be considered in the differential diagnosis of retrorectal tumors. T h e anatomy o f the retrorectal space is described and the embryology of a tailgut cyst briefly reviewed. T h e authors' purpose is to acquaint physicians and surgeons with the entity of tailgut cysts so that an earlier diagnosis can be made and the proper treatment effected. References I. Freier DT, Stanley JC, Thompson NW: Retrorectal tumors in adults. Surg Gynecol Obstet 132: 681, 1971 2. Gius JA, Stout AP; Perianal cysts of vestigial origin. Arch Surg 37: 268, 1938 3. Jackman RJ, Clark PL, Smith ND: Retrorectal tumors. JAMA 145: 956, 1951
