Diagnosis and Management of Sacral and Retrorectal Tumors

Introduction

Tumors of the sacrum and retrorectal space are rare. Two reviews of patients at the Cleveland Clinic found 50 patients between 1928 and 1985 ( Table 26-1 ) and 87 patients between 1981 and 2011, in line with other studies indicating that in major referral centers, 1.4 to 6.3 patients will be diagnosed with these tumors per year. The annual incidence of congenital retrorectal tumors is estimated to be from 0.0025% to 0.013%.

Anatomy of the Retrorectal Space

The retrorectal (presacral) space is a potential space that becomes apparent only when a mass expands into it. Anatomic descriptions of the area are inconsistent because of controversy over the nomenclature of the endopelvic fascia, and in particular, the definition of Waldeyer fascia. The most generally accepted definition describes the retrorectal space as bounded anteriorly by the mesorectal fascia and mesorectum, posteriorly by the presacral fascia over the sacrum and coccyx, superiorly by the peritoneal reflection, and inferiorly by the fusion of the rectal visceral fascia and the parietal presacral fascia over the levator ani and coccygeal muscles. Laterally, it is bounded by the iliac vessels and the ureters ( Fig. 26-1 ). It is divided into superior and inferior sections by the rectosacral fascia, which passes from S2, S3, or S4 to the rectum, inserting approximately 3 to 5 cm above the anorectal junction where it joins the mesorectal visceral fascia. The space normally contains loose connective tissue, the middle sacral artery, the iliolumbar vessels, the superior and middle hemorrhoidal vessels, lymphatics, and branches of the sympathetic and parasympathetic nervous systems. Some authors consider only the compartment superior to the rectosacral fascia to be the retrorectal space and label the inferior compartment the supralevator space.

The embryologic hindgut and the neuroectoderm fuse in the retrorectal space. As a result, many different kinds of tumors can be found there arising from ectodermal, endodermal, neural crest, or totipotential cells in the retrorectal space itself or from adjacent notochordal remnants, as well as cartilaginous and bony structures.

Classification Systems

Several classification systems for masses in the retrorectal space have been proposed. One of the most common, used by Uhlig and Johnson, divides these masses into five categories: (1) congenital, (2) inflammatory, (3) neurogenic, (4) osseous, and (5) miscellaneous. These categories were subdivided into benign and malignant by Dozois et al. Lev-Chelouche et al used four categories: (1) benign congenital, (2) malignant congenital, (3) benign acquired, and (4) malignant acquired. We adapted this classification, as shown in Box 26-1 . Finally, as an aid to operative planning, Papallardo et al. suggested a classification of tumors based on imaging findings according to the site of origin: (1) the presacral space, (2) the sacrum or spinal cord and growing anteriorly, and (3) the rectum and growing posteriorly. The most common lesions are described in the following sections.