Because ependymal cells may be found within the coccygeal ligament as well as in heterotopic position and thus ependymomas may rarely occur in extraspinal locations. Extraspinal ependymomas may be found in four general situations: metastatic extension from a primary central nervous system neoplasm; direct extension into the soft tissue of the sacrococcygeal area from primary ependymoma of the spinal cord, filium terminale, or cauda equina; primary tumor of the skin and subcutaneous tissue without any demonstrable connection with the spinal cord; and primary presacral, pelvic, or abdominal tumor [5
]. Our case would correspond to the third situation of this classification.
Since the original description of an extraspinal ependymoma by Mallory in 1902 [4
], there have been several case reports and sporadic reports in the literature [2, 3, 5-7]. With the review of literature, subcutaneous sacrococcygeal myxopapillary ependymomas are usually presented as a slow-growing mass in the intergluteal fold and often mistaken for a pilonidal cyst or other benign mass. The differential diagnosis includes pilonidal disease, teratoma, lipoma, chordoma, myxoid chondrocarcinoma, metastatic mucoid carcinoma and metastatic carcinoid [7
]. Our patient also clinically diagnosed as a pilonical cyst.
The most important treatment for cure lies with complete surgical excision at the initial operation if possible. Coccygectomy and adjuvant radiotherapy may be needed if the tumor is attached to coccyx, in case of incomplete excision, or metastatic cases [2
]. Long-term and close follow-up should be needed, because these tumors may recur locally or become metastatic. Sonneland et al. [9
] reported that the extrameningeal ependymomas tend to metastasize more frequently than their intrameningeal counterparts which originate in the cauda. Also Helwig and Stern [5
] reported four (17%) of 23 patients developed metastases and two of the metastasized patient died from progressive pulmonary and pleural metastasis. The best chance of survival of any patient with this type of tumor is achieved by complete excision at the time of the first operation [10
We report a case of a subcutaneous sacrococcygeal myxopapillary ependymoma in an Asian female. To our knowledge, there has been no previous report of a case in an Asian patient. Although very rare, extraspinal myxopapillary ependymomas must be considered in the differential diagnosis of postsacral mass lesion. And postoperatively, long-term follow-up should be needed for evaluation of metastasis.