Clinical Radiology (2002) 57: 523±536 doi:10.1053/crad.2001.0926, available online at http://www.idealibrary.com on
Case Reports Submucosal Rectal Lipoma Presenting as Rectal Prolapse J. C . E VA NS *, P. CA R T E R {, S. S HA B IR {, C . J. G A RV E Y * *Department of Radiology, Royal Liverpool University Hospital NHS Trust, Liverpool, U.K. and {Department of Surgery, Royal Liverpool University Hospital NHS Trust, Liverpool, U.K.
Submucosal lipomas of the large bowel are uncommon, found in 0.25% of post-mortems. Occasionally they occur in the rectum, and may cause rectal bleeding, pain, or tenesmus. Presentation with rectal prolapse is very unusual, and may lead to a misdiagnosis of simple mucosal prolapse, resulting in inappropriate management. This case demonstrates the proctographic and magnetic resonance (MR) imaging in a patient who presented with recto-anal prolapse of a submucosal rectal lipoma.
of intermediate to high signal on both T1W and T2W images, with contained low signal septae (Fig. 3). The margins were regular and smooth, with a well-de®ned low signal capsule. There was no evidence of lymphadenopathy. The appearances were those of a submucosal rectal lipoma. At surgery, there was a pedunculated area of redundant mucosa on the posterior rectal wall, which had started to develop a pseudo-stalk, presumably as a result of repeated prolapse. At operation, the lesion could be pulled through the anal canal. The base was injected with adrenaline (epinephrine) and the lipoma excised completely. Two months post-operatively the patient remains asymptomatic.
CASE REPORT
DISCUSSION
A 77-year-old woman presented with a 6-month history of rectal prolapse. She described a sensation of something passing through her anal canal during defecation, and then having to manually re-insert this soft mass at the end of defecation. There was no history of rectal bleeding, weight loss or tenesmus. She had complained of constipation for many years which was controlled with lactulose. Abdominal examination was unremarkable. Rectal examination and rigid sigmoidoscopy demonstrated mild perineal descent and an anterior mucosal prolapse. The prolapse was banded and the patient reviewed 6 weeks later, when she was still complaining of the same symptoms. An anterior rectal mucosal excision was performed, but still the symptoms persisted. Re-examination revealed an abnormal posterior upper rectal wall, which appeared to be intussuscepting into the lower rectum on straining. Defecating proctography was performed. Proctography demonstrated signi®cant ano-rectal junction descent in the sitting position, with further descent during defecation (Fig. 1a). There was a recto-rectal intussusception during early emptying, with the development of a rounded mass within the posterior rectal wall. This mass, measuring approximately 3 cm in diameter, prolapsed into the anal canal during the latter stages of defecation (Fig. 1b). Barium passed anterior to the mass, which would be inconsistent with a true intussusception. At this stage, the dierential diagnosis included rectal wall tumour, mesorectal cyst and enterocele. Rectal MRI was performed. Endorectal MRI was performed on a 0.5 T magnet (Philips T5II Gyroscan, Eindhoven, Germany). The coil was inserted into the rectum and a balloon surrounding the coil in¯ated with 70±100 ml of air, to ®ll the rectum. This demonstrated a 3.5 2.5 cm mass within the posterior wall of the rectum (Fig. 2). The mass appeared to lie super®cial to the muscularis propria, in a submucosal position. It was
Lipomas are the commonest submucosal tumour of the large bowel, found in 0.25% of post-mortems [1], and may be multiple in 14% of cases [2]. Leiomyomas and other mesenchymal tumours, such as ®broma and neuro®broma, are seen less commonly. Submucosal lipomas are commonest in the large bowel followed by the small bowel, stomach and oesophagus, respectively. They are usually located in the caecum and ascending colon and may present with crampy abdominal pain due to intermittent intussusception, rectal bleeding, or are found incidentally. One-third of lipomas have a short pedicle, thought to be due to repeated peristalsis, and this may lead to a mistaken diagnosis of a polyp. On computed tomography (CT) they appear as a well-de®ned ovoid mass, intimately associated with the bowel wall, and of fat attenuation. On MR, the fatty nature of the lesion is readily appreciated [3]. Because they are soft tumours, lipomas may change shape and size between examinations. Liposarcomatous degeneration has not been reported. In the rectum, leiomyomas are more common than lipomas [4]. Other benign intramural masses in the rectum include duplication cysts, tailgut cysts, lymphangioma, haemangioma, colitis cystica profunda, and carcinoid, although the latter may metastasize in 10% of cases. Submucosal rectal lipoma presenting with prolapse is rare, and only two cases were found in our literature search [5]. Examination may easily overlook the lesion, as the lipoma is a soft tumour and is easily deformed by the examining ®nger. Defecating proctogaphy is often the ®rst imaging
Author for correspondence: Dr Jonathan Evans, 54 Grange Cross Lane, West Kirby, Wirral, Merseyside CH48 8BQ, U.K. E-mail:
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2002 The Royal College of Radiologists
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Fig. 2 ± Sagittal T1W MR image showing endorectal coil in position (star). The submucosal lipoma is clearly seen in the upper posterior wall of the rectum (arrow). The balloon coil compresses the lipoma producing a concave inner margin.
Fig. 1 ± (a) Lateral view of defecating proctogram. In the resting state, there is signi®cant ano-rectal descent with the ano-rectal junction dropping several cm below a standard reference line connecting bottom of pubic symphysis (asterisk) to lower sacrum (star). No ®lling defect is seen within the rectum at this stage. (b) During the later stages of defecation, a smooth, 3 cm diameter mass (asterisk) has prolapsed into the anal canal. A narrow stream of barium passes anterior to the mass (arrowheads). There is also moderate recto-rectal intussusception (large arrow).
investigation used to assess the ano-rectal region. Submucosal lipomas may be seen as a smooth intramural mass projecting into the lumen of the rectum. The tumour may become polypoid during defecation, and be pushed downwards into the lower rectum or anal canal as in this case.
Fig. 3 ± Axial T2W MR image showing similar signal characteristics of the lipoma and surrounding ischio-rectal fat. Low signal septae are seen within the lipoma. Also, a low signal capsule is seen around the lipoma (arrowheads), separate from the outer muscle layer of the rectal wall (large arrow).
Occasionally the lipoma adopts a ¯attened appearance post-evacuation, described as the `squeeze sign' [6], although this is typically seen with lipomas in the more proximal large bowel. Mucosal intussusception may be mimicked if the lipoma prolapses; however, on closer scrutiny of the proctogram images in this case, barium is observed to pass around the mass rather than through its centre as in recto-rectal or recto-anal intussusception. Also
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the lipoma is well de®ned and smooth whereas mucosal intussusception tends to be more irregular in outline. When determining how best to investigate this mass, three imaging possibilities are available: CT, endoluminal ultrasound and MR. CT has some drawbacks when assessing rectal lesions because of the inability to identify the individual layers of the bowel wall. In this case CT would most likely have con®rmed the fatty nature of the lesion. Endorectal ultrasound, if performed, would be expected to reveal a hyper-echoic lesion super®cial to the muscularis propria, which may change shape as the transducer is used to apply pressure. Our preferred practice is to perform MR using a dedicated endorectal coil. Using this technique, we can reliably identify the layers of the bowel wall and relate lesions to individual layers. Alternatively, MR with a pelvic phased-array coil could be used as this has been employed to show the layers of the rectal wall. This case elegantly demonstrates the ability to identify the rectal wall layers. The soft consistency of the tumour can be inferred by recognizing the crescentic impression of the balloon on the luminal surface of the lipoma (Fig. 3). Although the vast majority of patients who present with rectal prolapse or problems with defecation will have a
mucosal or neuromuscular cause, this case demonstrates that intramural or pararectal tumours should always be considered. If appearances on defecating proctography are unusual, or if the patient has not responded to prolapse surgery, then pelvic imaging with a technique capable of demonstrating the layers of the rectal wall should be employed.
REFERENCES 1 DaÈhnert W. Gastrointestinal disorders. In: Mitchell CW, ed. Radiology Review Manual, 3rd edn. Baltimore, USA: Williams and Wilkins, 1996;612. 2 Bruneton JN, Quoy AM, Dageville X, Lecompte P. Les lipomes du tube digestif: revue de la litteÂrature aÁ propos de 5 cas. Ann Gastroenterol Hepatol (Paris) 1984;20:27±32. 3 Younaphan CM, Ros PR, Burton SS. MR imaging of colonic lipoma. J Comput Assist Tomogr 1991;15:492±494. 4 Jaworski RC. Benign mesenchymal tumours of the colon and rectum: a retrospective study. Aust N Z J Surg 1980;50:586±588. 5 Cardona-Huerta S, Hurtado-Ramirez MB. Dos casos de lipoma de colon como causa de prolapso rectal. Rev Invest Clin 1998;50: 153±154. 6 Hurwitz MM, Redleaf PD, Williams HJ, Edwards JE. Lipomas of the gastrointestinal tract: an analysis of seventy-two tumours. AJR Am J Roentgenology 1967;99:84±89.
doi:10.1053/crad.2001.0943, available online at http://www.idealibrary.com on
Radiological Findings and Molecular Genetic Con®rmation of Cleidocranial Dysplasia I L A N G O L A N *, UW E BA U M E R T *, PA U L HE L D{, S T E FA N F EU E R B AC H {, D I E T E R M UÈ ûI G{ *Department of Orthodontics, Division Craniofacial Genetics and {Department of Diagnostic Radiology {Department of Orthodontics, University of Regensburg, Regensburg, Germany Cleidocranial dysplasia (MIM 119600) is a rare autosomal dominant disease with a wide range of variability (Fig. 1) [1,2]. The phenotype is characterized by general dysplastic bone formation manifested in typical malformations in the skull, the pelvis and the thoracic region [3,4]. Mutations in the core-binding factor a1 (CBFA1) gene (OMIM 600211), located on chromosome 6p21, have been shown to be the cause of cleidocranial dysplasia [5±8]. This report describes the correction of a mistaken initial diagnosis, based on an interdisciplinary radiologic-molecular genetic approach. CASE REPORT An 18-year-old patient came to our clinic for dental treatment. Skeletal growth and development were retarded. No signs of mental retardation were apparent. In early childhood, he had been diagnosed with Rubinstein±Taybi syndrome, probably because of his broad Author for correspondence and guarantor of study: Ilan Golan DMD, Department of Orthodontics, University of Regensburg FranzJosef-Strauss-Allee 11, 93053 Regensburg, Germany. Fax: 49 / 941 / 9446169; E-mail:
[email protected]
thumbs and toes, ®ndings typical for the Rubinstein±Taybi syndrome (therefore also referred to as broad thumb±hallux syndrome). Due to the initial clinical diagnosis, the parents had expected mental retardation and a severely limited lifespan. No hereditary diseases in the family were known. On examination, the patient showed a straight pro®le with prominent chin and beaked nose. The thorax was funnel shaped. Most striking was the abnormal hypermobility of the shoulders. Based on the Zurich growth centile diagram, the patient's height of 170 cm at the age of 18 years corresponded to the 20th centile. A radiological examination regarding osseous malformations was carried out. Lateral cephalometric radiographs and panoramic radiographs were taken to analyse the skeletal morphology of the skull and face, and to evaluate dental development. In addition, plain radiographs were taken in order to assess the shoulders (Figs 2a and b), spine (Fig. 3), pelvis (Fig. 4), hands (Fig. 5a) and feet (Fig. 5b). To further support the clinical and radiological based suspicion of cleidocranial dysplasia, a molecular genetic analysis of the underlying gene was carried out using ampli®cation through polymerase chain reaction (PCR) with exon-speci®c primer pairs (Table 1), as follows: after informed consent was given, genomic DNA was isolated from whole venous blood. A combined approach using the single-strand conformational polymorphism (SSCP) method and/or automated sequencing was used to analyse the amplicons [9]. In order to con®rm the molecular ®ndings on exon 2, this exon was sequenced twice in both directions using two independent PCR ampli®cations.
