Bursal cyst (bursitis) of the coccygeal region clinically mimics sacrococcygeal meningocele

Case report: Bursal cysts (bursitis) are attributed to repeated microtrauma of the connective tissue around the synovial joint and are rare in the coccygeal region. Materials and methods: A 10-year-old boy had a subcutaneous tumor at the midline of the buttock. He could not walk and slid himself in a seated position because of psychomotor retardation. MR images showed a cystic lesion overlying the coccygeal bone, the intensity of which was identical to cerebrospinal fluid (CSF). Although meningocele was suspected, constructive interference in steady-state (CISS) MR images clearly depicted a discontinuity between the cyst and CSF space. Results and conclusion: It was conceivable that repeated friction between the coccygeal bone, which projected posteriorly, and overlying subcutaneous tissue during movement resulted in the formation of a bursal cyst. In addition to total removal of the cyst, the coccygeal bone was planed away to prevent friction. We should keep this rare clinical entity in mind in cases that appear to be sacrococcygeal meningocele.