Imaging of presacral masses--a multidisciplinary approach.

BJR Received: 24 August 2015 © 2016 The Authors. Published by the British Institute of Radiology Revised: 22 January 2016 Accepted: 28 January 2016 doi: 10.1259/bjr.20150698 Cite this article as: Patel N, Maturen KE, Kaza RK, Gandikota G, Al-Hawary MM, Wasnik AP. Imaging of presacral masses—a multidisciplinary approach. Br J Radiol 2016; 89: 20150698. REVIEW ARTICLE Imaging of presacral masses—a multidisciplinary approach NISHANT PATEL, MD, MBA, KATHERINE E MATUREN, MD, MS, RAVI K KAZA, MD, GIRISH GANDIKOTA, MD, MAHMOUD M AL-HAWARY, MD and ASHISH P WASNIK, MD Department of Radiology, University of Michigan Hospital and Health Systems, Ann Arbor, MI, USA Address correspondence to: Dr Ashish P Wasnik E-mail: ABSTRACT Our objective is to describe an approach for retrorectal/presacral mass evaluation on imaging with attention to imaging features, allowing for refinement of the differential diagnosis of these masses. Elaborate on clinically relevant features that may affect biopsy or surgical approach, of which the radiologist should be aware. A review of current literature regarding the diagnosis and treatment of retrorectal/presacral masses was performed with attention to specific findings, which may lend refinement to the differential diagnosis of these masses. Cases were obtained by searching through a radiology database at a single institution after Institutional Review Board approval. Recent advances in imaging and treatment methods have led to the increased role of radiology in both imaging and tissue diagnosis of retrorectal masses. Surgical philosophies surrounding the treatment of these masses have not significantly changed in recent years, but there are a few key factors of which the radiologist must be aware. The radiologist can offer refinement of the differential diagnosis of retrorectal masses and can elaborate on salient findings which could alter the need for neoadjuvant chemoradiation therapy, pre-surgical tissue diagnosis and surgical approach. This article presents an imaging approach to retrorectal/presacral masses with emphasis on findings which can dictate the ultimate need for neoadjuvant therapy and pre-surgical tissue diagnosis and alter the preferred surgical approach. This article consolidates key findings, so radiologists can become more clinically relevant in the evaluation of these masses. INTRODUCTION The presacral space is a site of totipotential cells with a combination of the embryologic hindgut and neuroectoderm, and the pathologies occurring in this space may thus have a singletissue or multitissue origin from osseous, mesenchymal or neural tissues. While the smaller lesions are asymptomatic, with incidental detection during imaging for unrelated abdominal or pelvic symptoms, larger masses may manifest with pelvic symptoms or altered bowel habits. Imaging plays a crucial role in diagnosis (including image-guided tissue sampling) and can define the extent of a lesion to guide surgical planning. This article provides a review of the anatomy and pathologies of the presacral space, with emphasis on the role of imaging in diagnosis and treatment planning. ANATOMY The presacral space is an extraperitoneal potential space between the upper two-thirds of the rectum and the sacrum. The retrorectal/presacral space is bounded anteriorly by the rectum and mesorectal fascia, superiorly by the peritoneal reflection of the rectosigmoid colon, inferiorly by the rectosacral/Waldeyer’s fascia, posteriorly by the presacral fascia and laterally by the iliac vessels and ureters (Figure 1).1 The retrorectal space can be further divided into the anterior retrorectal and posterior presacral space, divided by the presacral fascia. Imaging allows limited differentiation of these spaces. A surgical approach to lesions in this region is discussed later. A classification of pathologies involving the presacral/ retrorectal space based on the origin is presented in Table 1. CONGENITAL Cystic lesions Congenital cystic lesions are commonly encountered presacral masses with a female predilection.2 The majority of these lesions are benign, including developmental cysts (tailgut, rectal duplication, dermoid and epidermoid cysts) or anterior sacral meningoceles. Developmental cysts constitute approximately two-thirds of congenital presacral masses.3,4 Among these, tailgut cysts, also known as retrorectal cystic hamartoma, are the most common asymptomatic retrorectal masses found in adults.5 Tailgut cysts are often multiloculated cysts containing mucin and lack a muscular layer, a differentiating feature from rectal duplication cysts, which can be confirmed on endorectal BJR Patel et al Figure 1. An lllustration demonstrating the presacral space. The boundaries are as follows: the rectum anteriorly, peritoneal reflection superiorly, levator ani muscle and anococcygeal ligament inferiorly, sacrum/coccyx posteriorly. R, rectum; UB, urinary bladder; UT, uterus. ultrasound.6–8 Up to 13% of these cysts may undergo malignant transformation, and for this reason, they are removed.9 Rectal duplication cysts may be associated with other congenital abnormalities of the anorectal region and bladder/urethra.7 Sacrococcygeal teratoma is the most common presacral mass in children containing all three germ-cell lineages.10 Benign mature teratomas tend to be predominantly cystic containing fat, sebum, calcification and soft tissue from dermoid plugs. On imaging, congenital developmental cysts are seen as well defined, unilocular or multilocular, cystic masses ranging from simple to complex in their internal contents (Figure 2). Thin wall calcifications may be seen with tailgut cysts. MRI is helpful in defining the anatomic relationship to adjacent structures and assessing for the presence of an enhancing or necrotic soft tissue favouring malignant transformation. Increased T1 weighted signal intensity on fat-saturated images represents haemorrhage, mucin or proteinaceous content, suggesting complicated cysts (Figure 3). The presence of mural nodularity and post-contrast enhancement should be viewed with suspicion for malignant transformation in congenital cystic masses. Anterior sacral meningocele These are rare congenital lesions with female predominance and are associated with other congenital anomalies in 50% of cases.11 Such anomalies include the spina bifida, tethered spinal cord, imperforate anus, uterine/vaginal duplications and presacral lipomas.3,12,13 These lesions have a classic clinical presentation of headache during valsalva owing to increased cerebrospinal fluid (CSF) pressure transmitted via the Table 1. Classification scheme for presacral masses Origin Benign Malignant Cystic hamartoma Immature teratoma Duplication cyst Yolk sac tumour Congenital Dermoid cyst (mature teratoma) Anterior sacral myelomeningocele Aneurysmal bone cyst Giant-cell tumour Osseous Osteosarcoma Ewing’s sarcoma Chondrosarcoma Plasmacytoma Metastasis Mesenchymal Myelolipoma Fibrosarc (...truncated)