ailgut cyst or retrorectal cystic

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1 bdominal Imaging Yang et al. MRI of Tailgut Cyst Dal Mo Yang 1 Chul Hi Park 1 Wook Jin 1 Suk Ki Chang 1 Jee Eun Kim 1 Soo Jin Choi 1 Dong Hae Jung 2 Yang DM, Park CH, Jin W, et al. Received June 5, 2004; accepted after revision ugust 26, Department of Radiology, Gachon Medical College Gil Medical Center, 1198, Guwol-Dong, Namdong-Gu, Incheon , South Korea. ddress correspondence to D. M. Yang (dmyang@ghil.com). 2 Department of Pathology, Gachon Medical College Gil Medical Center, Incheon , South Korea. JR 2005;184: X/05/ merican Roentgen Ray Society Original Report Tailgut Cyst: MRI Evaluation OJECTIVE. The purpose of our study was to evaluate the MRI features of tailgut cysts in five patients. CONCLUSION. Our results suggest that MRI may be useful in the diagnosis of tailgut cyst. multilocular cystic mass in the presacral space is a characteristic MRI finding of tailgut cyst, which may also be revealed as a cystic mass consisting of a large cyst accompanied by a small peripheral cyst. However, further studies are necessary to establish the usefulness of MRI for evaluating tailgut cysts. ailgut cyst or retrorectal cystic T hamartoma is a rare congenital lesion thought to arise from vestiges of an embryonic hindgut and is found in the retrorectal or presacral space [1]. lthough several reports have described the pathologic features of tailgut cysts [1 3], a paucity of information regarding their imaging features is available [4 8]. To our knowledge, the MRI features of tailgut cysts have been reported only in case reports [6 8]. Here, we describe the MRI findings of tailgut cyst. Materials and Methods We retrospectively reviewed the medical records and radiologic features of tailgut cysts in five consecutive patients who presented between 1996 and ll five patients underwent MRI performed with a 1.5-T scanner (Magnetom Vision, Siemens) using a surface coil. ll patients underwent sagittal and axial T1-weighted sequences with the following parameters: TR/TE, 600/14; matrix; 2 excitations; 20-cm field of view; and 6-mm section thickness with a 1.5-mm gap. ll patients underwent sagittal and axial T2-weighted imaging with the following parameters: 4,300/132; echo-train length of 16; matrix; 2 excitations; 20- cm field of view; and 6-mm section thickness with a 1.5-mm gap. Four patients also underwent CT. ll MR and CT images were reviewed retrospectively to determine the size, appearance, and location of the lesions. ll five patients underwent complete surgical excision of the mass. The pathology reports were reviewed, and the pathologic findings correlated with the imaging findings. Each patient s clinical history was reviewed. Results The clinical, MRI, CT, and pathologic findings in patients with tailgut cysts are summarized in Table 1. ll patients were women, with an age range of years (mean, 44 years). Two of the five patients presented with constipation. Two had right buttock pain and abdominal pain individually, and the remaining one had the mass detected incidentally during workup for other medical problems. In three of five cases, MRI revealed multilocular cystic masses in the presacral space (Fig. 1). In the other two cases, the mass consisted of a large cyst accompanied by a small, peripherally located cyst, which were both located in the presacral space (Figs. 2 and 3). The size of the tailgut cysts ranged from 4.5 to 12 cm, with a mean of 7.6 cm. ll the lesions were hypointense on T1-weighted images, whereas on T2-weighted images, four of the lesions showed high signal intensity (Figs. 1 3) and one showed mixed high and low signal intensity due to hemorrhage. In one of the five, there were multiple small foci with low signal intensity within the mass on T2-weighted images, which corresponded to JR:184, May

accompanied by daughter cyst 2 31 F Right buttock pain Consists of large cyst accompanied by daughter cyst 3 30 F Low abdominal pain Multilocular 4 67 F Constipation Multilocular

Keratinous material Lined by squamous and columnar Mucoid fluid Lined by transitional and columnar Dark, yellowish fluid Lined by squamous Clear fluid with mucinous material

2 Yang et al. TLE 1 Clinical, MR, CT, and Pathologic Features of Tailgut Cysts Patient ge(yr) Sex Symptom MR Features CT Features Pathology 1 45 F Constipation Consists of large cyst accompanied by daughter cyst 2 31 F Right buttock pain Consists of large cyst accompanied by daughter cyst 3 30 F Low abdominal pain Multilocular 4 67 F Constipation Multilocular 5 45 F Incidental detection Multilocular hyper/ hypointense on T2WI Unilocular, hypodense None Multilocular, hypodense Multilocular, hypodense Multilocular, hypo/ hyperdense Keratinous material Lined by squamous and columnar Mucoid fluid Lined by transitional and columnar Dark, yellowish fluid Lined by squamous Clear fluid with mucinous material Lined by transitional and columnar Hemorrhage Lined by transitional, columnar and squamous C Fig year-old woman with low abdominal pain., Enhanced CT scan shows small-sized multilocular hypodense masses (arrows) in presacral space., On T1-weighted image, masses are hypointense. C, On T2-weighted image, masses (arrows) are hyperintense JR:184, May 2005

MRI of Tailgut Cyst aggregates of keratin (Fig. 2).

However, in one of the two cases, a small cyst was not detected on the T1- weighted image (Fig. 3).

On gross pathology, these masses were composed of variable-sized cysts containing keratinous material or mucous fluid in four cases. In the other case, the cyst contained hemorrhage.

Discussion The tailgut or postanal gut is the most caudal part of the hindgut, distal to the future anus. It normally involutes by the eighth week of embryonic development.

3 MRI of Tailgut Cyst aggregates of keratin (Fig. 2). In two cases with a mass consisting of a large cyst accompanied by a small peripheral cyst, the small cyst was clearly identified on T2-weighted images. However, in one of the two cases, a small cyst was not detected on the T1- weighted image (Fig. 3). In the four patients who underwent CT, the scans revealed discrete, well-defined, hypodense, presacral masses with thin walls. These lesions were unilocular (n = 1) and multilocular (n = 3) on CT. On gross pathology, these masses were composed of variable-sized cysts containing keratinous material or mucous fluid in four cases. In the other case, the cyst contained hemorrhage. In all cases, microscopic examination revealed fibrous tissue lined by squamous or a combination of columnar, squamous, or transitional (Fig. 2D). Discussion The tailgut or postanal gut is the most caudal part of the hindgut, distal to the future anus. It normally involutes by the eighth week of embryonic development. If a tailgut remnant persists, it may give rise to a tailgut cyst [1]. Tailgut cyst is more common in women and usually presents in middle age, C but it can be discovered at any age [4, 5]. It is usually detected as an asymptomatic mass but may be found in patients with abdominal pain or constipation [4]. Rarely, malignant transformation of the tailgut cyst has been reported, in which case adenocarcinoma, carcinoid, neuroendocrine carcinoma, and sarcoma arise within the cyst [8 10]. Grossly, tailgut cyst is a multiloculated, cystic mass with a thin wall and glistening lining and is filled with a mucoid material [1, 2]. It usually measures several centimeters in diameter. Infection or inflammation may cause fibrosis of the cyst wall and breakdown of the cyst lining. D Fig year-old woman with history of constipation., Enhanced CT scan shows well-defined hypodense mass (arrow) with thin wall in presacral space. Rectum (arrowhead) is compressed and anteriorly displaced., On T1-weighted image, mass (arrow) is hypointense. C, On T2-weighted image, mass (arrow) is hyperintense, and small-sized hyperintense mass (arrowhead) is identified at posterior portion of large mass. D, Photomicrograph of histologic specimen shows wall of cyst, which is lined with squamous (arrowheads). (H and E, 100) JR:184, May

Yang et al. Fig. 3. 31-year-old woman with right buttock pain., T1-weighted image shows well-defined hypointense mass (arrow) in presacral space. Rectum (arrowhead) is anteriorly displaced.

Microscopically, it is characterized by the presence of a cyst lined with multiple, varying types of ; columnar, mucinsecreting predominates, while other areas of squamous and transitional often

4 Yang et al. Fig year-old woman with right buttock pain., T1-weighted image shows well-defined hypointense mass (arrow) in presacral space. Rectum (arrowhead) is anteriorly displaced., On T2-weighted image, mass (arrow) is hyperintense, and small-sized hyperintense mass (arrowhead) is identified at posterior portion of large mass. Microscopically, it is characterized by the presence of a cyst lined with multiple, varying types of ; columnar, mucinsecreting predominates, while other areas of squamous and transitional often coexist [1]. The radiologic findings on sonography, CT, and MRI have been described. Sonography shows a multilocular, retrorectal cystic mass. Internal echoes may be found within the cyst. They are due to the multicystic nature of the mass and the presence of gelatinous material or inflammatory debris within the cyst [4]. CT shows a discrete, well-marginated, presacral mass with water or soft-tissue density, depending on the contents of the cyst [4, 5]. Calcifications may be seen in the cyst wall [6]. When the mass is large, the rectum is displaced by the mass [6]. If concurrent infection or malignant transformation occurs, CT may reveal loss of discrete margins and involvement of contiguous structures [4]. On MRI, tailgut cyst usually has low signal intensity on T1-weighted images and high signal intensity on T2-weighted images [6 8]. However, it may have high signal intensity on T1-weighted images due to presence of mucinous materials, high protein content, or hemorrhage in the cyst [7, 9]. In addition, a malignant change or fibrous tissue within the cyst may show as irregular wall thickening or a polypoid mass with intermediate signal intensity on both T1- and T2-weighted images with enhancement after the IV administration of paramagnetic contrast material [8, 9]. In most of our cases, tailgut cysts were hypointense on T1-weighted images and hyperintense on T2-weighted images. However, one of the five cysts appeared as low signal intensity on T2-weighted images. This finding correlated with that of pathology because hemorrhage contributed to the finding. On MRI, tailgut cyst has been reported with a unilocular or multilocular cystic appearance [6 8]. However, Kim et al. [7] reported that a multilocular appearance with internal septa on T2-weighted images is a finding unique to tailgut cyst. In our study, three of five cases had multilocular cystic masses. Interestingly, we observed that the other two of our five cases had a large cyst accompanied by a small peripheral cyst. In addition, the multilocular appearance of these cystic masses was more clearly visualized on MRI than on CT. In one of the four patients who underwent CT, the cyst appeared unilocular on CT. However, a small cyst was identified at the peripheral portion of the large cyst on MRI. In addition, the small cyst was clearly identified on T2- weighted rather than on T1-weighted images. Therefore, we believe that T2- weighted MR images offer clearer delineation of the multilocular appearance of the cystic masses and may be useful for the detection of a small cyst. Kim et al. [7] asserted that for the evaluation of a presacral mass, MRI has the advantage over CT of being able to offer multiplanar capabilities and good tissue contrast. In addition, we believe that sagittal MRI can be used to assess the relationship of the mass with the surrounding rectum and boney structures, and MRI may be helpful for surgical planning of the mass. Many differential diagnoses should be considered when a presacral cystic mass is discovered, including epidermoid cyst, dermoid cyst, rectal duplication cyst, anal gland cyst, cystic lymphangioma, and anterior meningocele [11 13]. Distinction of tailgut cyst and other presacral cysts is important because of the malignant potential of a tailgut cyst [8]. However, because substantial overlap exists in the imaging findings of the presacral cysts, it is difficult to distinguish the imaging appearance of tailgut cyst from that of many other presacral cysts. Therefore, histologic analysis is essential to establish a definitive diagnosis of tailgut cyst. However, in the differential diagnosis of presacral cystic masses, we believe that the unilocular or multilocular characteristic is also important. mong the presacral cystic masses, epidermoid cyst, dermoid cyst, rectal duplication cyst, and anterior meningocele are usually unilocular [11 13]. In contrast, tailgut cyst and cystic lymphangioma are usually multicystic [11]. Therefore, careful analysis is required to determine whether the cystic mass is unilocular or multilocular. We believe that MRI may be useful for the differentiation of unilocular and multilocular 1522 JR:184, May 2005

5 MRI of Tailgut Cyst masses and especially for the detection of a small peripheral cyst. Our study was limited by being a retrospective and single-institution study. In addition, it was limited by the small sample size. Thus, further study will be necessary to examine more fully the MRI findings of tailgut cyst and the differentiation of tailgut cysts and other presacral cystic masses. Despite its rarity, tailgut cyst should be considered when a multicystic mass, or one accompanied by a small peripheral cyst, is present in the presacral space on MRI. Knowledge of these characteristic findings can be helpful in the distinction of presacral cysts. References 1. Marco V, Fernandez-Layos M, utonell J, Doncel F, Farre J. Retrorectal cyst-hamartomas: report of two cases with adenocarcinomas developing in one. m J Surg Pathol 1982;6: Mills SE, Walker N, Stallings RG, llen MS. Retrorectal cystic hamartoma: report of three cases, including one with a perirectal component. rch Pathol Lab Med 1984;108: Caropreso PR, Wengert P, Milford HE. Tailgut cyst: a rare retrorectal tumor report of a case and review. Dis Colon Rectum 1975;18: Johnson R, Ros PR, Hjermstad M. Tailgut cyst: diagnosis with CT and sonography. JR 1986;147: Ottery FD, Carlson R, Gould H, Weese JL. Retrorectal cyst hamartomas: CT diagnosis. J Comput ssist Tomogr 1986;10: Liessi G, Cesari S, Pavanello M, utini R. Tailgut cysts: CT and MR findings. bdom Imaging 1995;20: Kim MJ, Kim WH, Kim NK, et al. Tailgut cyst: multilocular cystic appearance on MRI. J Comput ssist Tomogr 1997;21: Lim KE, Hsu WC, Wang CR. Tailgut cyst with malignancy: MR imaging findings. JR 1998;170: Moulopoulos L, Karvouni E, Kehagias D, Dimopoulos M, Gouliamos, Vlahos L. MR imaging of complex tail-gut cysts. Clin Radiol 1999;54: Prasad R, min M, Randolph TL, Lee CS, Ma CK. Retrorectal cystic hamartoma: report of 5 cases with malignancy arising in 2. rch Pathol Lab Med 2000;124: Dahan H, rrive L, Wendum D, Ducou le Pointe H, Djouhri H, Tubiana JM. Retrorectal developmental cysts in adults: clinical and radiologic-histopathologic review, differential diagnosis, and treatment. RadioGraphics 2001;21: Nishie, Yoshimitsu K, Honda H, et al. Presacral dermoid cyst with scanty fat component: usefulness of chemical shift and diffusion-weighted MR imaging. Comput Med Imaging Graph 2003;27: eattie CH, Garvey CJ, Hershman MJ. Endorectal magnetic resonance imaging of a rectal duplication cyst. r J Radiol 1999;72: JR:184, May

Retrorectal cystic hamartomas are uncommon lesions

Retrorectal cystic hamartomas are uncommon lesions Retrorectal Cystic Hamartoma Report of 5 Cases With Malignancy Arising in 2 Anil R. Prasad, MD; Mahul B. Amin, MD; Todd L. Randolph, MD; Chong S. Lee, MD; Chan K. Ma, MD Background. Retrorectal cystic