1. To illustrate the various imaging feature of the common and unusual sacrococcygeal masses which include congenital lesions and neoplastic lesions with pathologic correlation 2. To recognize differential diagnosis of sacrococcygeal mass

Various pathologic masses which include congenital (spinal dysraphism, tailgut cyst, sacrococcygeal teratoma etc), infectious and neoplastic condition (sacrococcygeal canal tumors and bone tumors) can occur in the sacrococcygeal area. But, these lesions may present a diagnostic challenge due to low incidence rate and delayed nonspecific symptoms, such as lower back pain, radiculopathy. 1. Congenital lesion A. Spinal dysraphism - Open (myelocele, Myelomeningocele) - Closed (Lipomyelocele, Lipomyelomeningocele, Meningocele) B. Tumorous condition (presacral mass) - Sacrococcygeal teratoma, Meningeal cyst 2. Sacrococcygeal canal lesion A. Benign mass :...

1. Congenital lesion A. Spinal dysraphism Types (by defect in the overlying skin) - Open: Myelomeningocele (Fig. 1), Myelocele - Close: Lipomyelomeningocele (Fig. 2), Lipomyelocele (Fig. 3), Meningocele B. Tumorous condition Sacoccygeal teratoma (Fig. 4) Meningeal cyst (perineural cyst, Tarlov cyst) (Fig. 5) - Common developmental lesions (5%) - Abnormal dilatations of the meninges within the sacral canal or foramina by sliding of the meninges from a defective dura mater -Classification of meningeal cysts Type 1 – Extradural meningeal cysts (no neural tissue) 1A –...

Knowledge of the normal anatomy and familiarity with the imaging features of sacrococcygeal lesions are important for determining the type of mass or narrowing the differential diagnosis. Furthermore, functional MRI, including diffusion and dynamic contrast imaging, may be helpful in differentiating between benign and malignant sacrococcygeal tumors.

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Sun Ju Lee, M.D., PhD. Department of Radiology, Busan Paik Hospital, Inje University College of Medicine, South Korea E-mail address: [email protected]