Taha Takroni ( Department of Orthopaedics, College of Medicine, King Saud University, Riyadh, Saudi Arabia. )
Kamal Mohammad Al-Arabi ( Department of Orthopaedics, College of Medicine, King Saud University, Riyadh, Saudi Arabia. )
Saleem Sadiq ( Department of Pathology, College of Medicine, King Saud University, Riyadh, Saudi Arabia. )
Most of the spinal ependymomas are confirmed within the dura and become clinically evident by compression of the spinal cord and nerve roots of the cauda equine1. Rarely an ependymoma may arise in the bone or soft tissues of the pelvis or sacral subcutaneum2-4. We report a case of extraspinal ependymoma involving the lumbosacral region of the spine.
A 27-year old man admitted with a history of low grade back pain of six years duration. The pain gradually got worse. A year later, the pain started radiating down both legs to the outer aspect of the ankles, and it was constant and throbbing in nature. There were periods when the pain got slightly better, but he was never free of pain. There were no sensory changes. He had been taking non- steroidal anti-inflammatory analgesics for pain. Examination of the back showed no visible deformity. On flexion, he could reach just above the knee by the tip of his fingers. Straight leg raising was 600 bilaterally. Knee and ankle reflexes were present and normal. Plants reflexes were normal. His right extensor hallucis longus was weak (Grade IV), and he had a wasted right quadriceps by 1 cm difference. Tomogram (Figure 1)
showed extensive destructive lesion of the sacrum and L5 with involvement of soft tissue as well. CT scan (Figure 2)
confirmed the above findings. Blood investigations revealed an ESR of 40mm and a negative brucella titre. At surgery, the lumbosacral region was approached and a fungating mass was seen at the posterior edge of LI. Deroofmg of the sacral spinal canal was made and laminectomy of L5 and part of Li was done. The mass was dark brown in colour and very friable, but not vascular, it extended into the neural canal above Li and down into the sacruin. The mass was extradural, pushing the nerve roots laterally and anteriorly. All the accessible mass was scooped out. The histological examination of the tissue revealed a typical cellular ependymoma. Characteristic zones of high nuclear density and perivascular pseudorosettes were seen. However, true rosettes or papillary structures were not found. The tumour showed a positive staining with glial fibrillary acidic protein by the iminunoperoxidase technique (Figure 3).
At follow-up three nronths after surgery, the opera-don scar looked healthy. Lumbar flexion increased and he could now reach below knee with the tip of his fingers. His right extensor hallucis longus recovered to Grade V.
Extrasacral ependymoma is an extremely rare tumour. Mark and Loken5 studied 101 patients with histologically confirmed ependymomas over a 22-year period, of these, 48 were intracranial and 53 intraspinal. There was no example of an extrasacral ependymoma in theft study. However, Kernohan and fletcher- Kernohan6 reported three pre-sacral ependymomas collectdd over 26 years in a series of 55 ependmomas, giving a frequency of approximately 5%. Mallory7 was the first to describe an extraspinal ependymoma in 1902. By 1979, approximately 40 such cases had been reported in world literature3. The origin of the extraspinal ependymomas is disputed but most workers believe that the origin of these tumours is from "heterotopic" ependymal cells located within this region2,6,9. Extraspinal ependymomas present at two characteristic locations: in the soft tissue posterior to the sacrum or in the pelvis anterior to the sacrum in the retro-rectal space3. Those in whom the tumour arose posterior to the sacrum presented with a local mass which was occasionally painful while those whose tumour was pelvic in location presented predominantly with bowel and bladder dysfunction. The extrasacral ependymoma, being a rare lesion, is often mistaken for other inflammatory, congenital, neurogenic and osseous lesions in this area, like tuberculosis, pionidal cyst, neurofibroma and chordoma. Histopathological examination is the only way to confirm the diagnosis. In contrast to most of the reported cases in which the ependymomas were either papillary or myxopapillary, our case revealed a typical cellular ependymoma, with no papillary structures. The average survival time for the group of patients on whom information is available is approximately ten years3. Postoperative survival tends to be long. These tumours characteristically recur locally. Systemic metastases have been noted in several reported cases3,9-11. Early diagnosis is, therefore, important. Complete surgical removal should be attempted in all cases. If not feasible, then radiation therapy should be employed3.
1. Burger, P.C. and Vogel, P.S. Surgical pathology of the nervous system and its coverings. New York, Wiley 1982; p. 621.
2. Anderson, M.S. Myxopapillaryependymontas presenting in the soft tissue over the sacrococcygeal region. Cancer, 1966; 19:585.
3. Morantz, R.A., Kepes, JJ., Batnitzky, 6. and Masterson, B.J. Extraspinalependymomas. Report of three cases. J. Neurosurg., 1979; 51 : 383.
4. Vara-Thorbeck, it and Sanz-Esponera, J. Intrasacral ependymoma. Case report. 1. Neurosurg., 1970 32:589.
5. Mork, SJ. and Loken, AC. Ependymoma. A follow-up study of 101 cases. Cancer, 1977; 40:907.
6. Kernohan, J.W. and fletcher-Kernohan, EM. Ependymomas: A study of 109 cases, in Tumours of the nervous system: an investigation of the most recent advances. Edited byZabriskie EG., Frnntz AM., Hare CC Baltimore, Williams and Wilkins,, 1937, p. 182.
7. Mallory, KB. Three gliomata of ependymal origin: Two in thç fourth ventricle, one subcutaneous over the coccyx. J. Med. Res, 1902; 8:1.
8. Health, M.H. Presacral ependymoma. Case report and review of literature. Am. J. Clin. Pathol., 1963; 39: 161.
9. Russel, D.S. and Rubinstein, Li. Pathology of tumours of the nervous system. 4th ed. Baltimore, Williams & Wilkins, 1977, p.45.
10. Hendren, T.H. and Hardin, C.A. Extradural metastatic ependymoma. Surgety, 1963; 54: 880.
11. Wolff, M., Santiago, H. and Duby, M.M. Delayed distant metastases from a subcutaneous sacrococcygeal ependymoma. Case report, with tissue culture, ultrastructural observations, and review of the literature. Cancer, 1972; 30: 1046.