Isolated extradural sacrococcygeal ependymoma mimicking teratoma in a 5-year-old boy

Ependymoma represents the third most common malignant neoplasm of the central nervous system (CNS) in childhood, accounting for about 10% of cases. They predominantly occur in the posterior fossa and supratentorial area, and only 10% are diagnosed in the spinal cord. However, ependymomas account for 22% of all pediatric CNS tumors in the spinal cord (Ostrom et al., Neuro-Oncol 2016; 18 (Suppl 5): v1-v75). Since 1979, ependymomas have been graded according to the WHO classification on morphological criteria and growth pattern as grade III (anaplastic), grade II (classical), and grade I (myxopapillary; MPE) tumors (Gerstner ER et al., Semin Neurol 2018; 38 (1): 104-111). Localization of ependymomas in the sacrococcygeal region, first reported 120 years ago (Mallory FB, J Med Sci 1902; 8 (1): 1-10), occurs very rarely. Most sacrococcygeal ependymomas have been described as pure MPE with predominance in the posterior suprasacral compared to the presacral region, but mixed forms exist. Due to slow growth and nonspecific symptoms, considerably prolonged intervals to diagnosis have been reported. Many cases are initially misinterpreted as pilonidal cysts, followed by chordomas, teratomas, neurogenic tumors, lipomas, hematoma, abscess, or metastases. The clinical course is considered rather indolent with favorable prognosis in most cases although adverse courses have been published in children and in adults. The largest case series on children and adolescents with extraspinal MPE comprises seven patients with limited clinical details (Cimino PJ et al., Pediatr Blood Cancer 2014; 61 (11): 1969-1971). We here describe another child with an unusual ependymoma manifestation.