Presacral cystic lesions: Multimodality imaging features and diagnostic approach

The presacral space is an uncommon but clinically important location for congenital and neurogenic lesions, most of which are cystic or cystic-appearing on imaging. These lesions are frequently detected incidentally, and their overlapping computed tomography (CT) appearances often necessitate magnetic resonance imaging (MRI) for accurate characterization. This pictorial review presents a multimodality imaging approach to the spectrum of presacral cystic lesions, including tailgut cysts, epidermoid and dermoid cysts, rectal duplication cysts, anterior sacral meningoceles, and lymphangiomas, as well as cystic-appearing neurogenic tumors such as schwannoma and neurofibroma. Representative CT and MRI cases illustrate the imaging features that most reliably narrow the differential diagnosis, including macroscopic fat, diffusion restriction, a sacral defect with thecal sac communication, and the lesion's relationship to the rectum and adjacent fascial planes. A practical, stepwise diagnostic algorithm and a summary table incorporating these discriminators are provided to guide the practicing radiologist. Additional sections address common diagnostic pitfalls and mimics (e.g., tailgut cyst versus endometrioma, epidermoid cyst, or cystic schwannoma), imaging findings that should raise concern for infection or malignant transformation. Management considerations - including indications for surgical resection, imaging surveillance, and the role of multidisciplinary evaluation for atypical or indeterminate lesions - are also discussed. Familiarity with this diagnostic framework can help radiologists confidently characterize presacral cystic lesions, reduce preoperative misdiagnosis, and guide appropriate management.