The study involved 77 myxopapillary ependymomas of the spinal cord encountered during a 60-year period (1924-1983). This variant of ependymoma was, with few exceptions, limited to the lumbosacral region, particularly the filum terminale. The ma1e:female ratio was 1.7:1, and the mean age at diagnosis was 36.4 years (range, 6-82); a t presentation, 15 (19%) of the patients were in the first two decades of life. The duration of symptoms ranged from 1 month to 30 years; the most frequent complaint was low-back pain, and eight patients had undergone prior "disc surgery." Generally, myelographic block was disclosed. Preoperative cerebrospinal fluid protein levels averaged 2462 mg/dl. M yxopapillary ependymomas are slow-growing tumors that show no significant tendency to histologic dedifferentiation. Despite some variation in cytologic features and the presence of atypia and modest mitotic activity in most cases, the gross characteristics of the tumors appear to be of greater prognostic significance than the histologic features. Tumors that were encapsulated (25%) and amenable to intact, total surgical removal had a recurrence rate of lo%, whereas those that were removed either piecemeal (34%) or subtotally (41%) had recurrence rates of 19%. Overall survival, however, was more closely related to residual disease; total removal of tumor, whether intact (encapsulated) or piecemeal, resulted in longer survival (19 years) than did subtotal resection (14 years). Patients who died (6.5%) did so after a prolonged course marked by multiple recurrences. Radiotherapy may be of particular benefit to patients whose tumors are not amenable to intact total removal. Comer 56:883-893, 1985. PENDYMOMAS are uncommon intracranial lesions, E comprising approximately 5 % to 6% of all brain tumors.'*' In the spinal cord, however, they represent approximately 63% of all parenchymal tumors, although figures have ranged from 30%3-5 to 88%.lV6,' In 1932, Kernohan' divided his large series of spinal ependymo-mas into epithelial, cellular, and myxopapillary types, reflecting the morphologic spectrum of ependymal differentiation. Since that time, it has been repeatedly observed that the papillary pattern predominates among tumors of the filum terminale and conus medullaris.' Most such tumors demonstrate characteristic penvascular and intercellular accumulation of mucin as well as vascular hyalinization. This distinctive variant, the myxopapillary ependymoma, is almost exclusively observed in this location, although occasional examples are encountered at other spinal levels or intra~ranially.'~'~ Although likely to recur locally, myxopapillary ependy-momas primary in the cauda equina region rarely From the Departments of *Pathology and tNeurologic Surgery, Mayo Clinic and Mayo Foundation, Rochester. Minnesota. Address for reprints: Bernd W. Scheithauer, MD, Department of Pathology, Mayo Clinic, Rochester, MN 55905.

Thirty-one paragangliomas of the cauda equina region were studied (18 men and 13 women, ages 30-71 years [mean, 51 years]). Symptoms (1 day to 15 years in duration; mean, 48 months) included low back pain (87%), sensory/motor deficits (35%), urinary/fecal incontinence (13%), and paraplegia (6%). All patients studied had some myelographic block. Cerebrospinal fluid protein level ranged from 56 to 7000 mg/dl (mean, 1109 mg/dl). Most tumors were limited to the filum terminale, although one also involved the conus medullaris and two clearly arose from a caudal nerve root. All but one were entirely intradural. The tumor was totally excised in 26 cases; these patients remain disease-free. Of three patients whose tumors were excised subtotally, two received radiotherapy; the one non-radiated patient died of tumor-related complications. No autopsy was performed. One partially encapsulated tumor that had been subjected to biopsy and irradiation presented 1 year later with osseous invasion and retroperitoneal extension; 20 years after subtotal excision, this patient is alive but paraplegic. Morphologically, all tumors resembled paraganglioma at other sites. Cytologic atypia and mitotic activity generally were absent to mild. Fourteen (45%) cases showed ganglionic differentiation. All tumors tested were immunoreactive for neuron-specific enolase and neurofilament protein, and most showed somatostatin or serotonin reactivity. S-100 protein immunoreactivity was noted in sustentacular cells and, to a lesser extent, within chief cells and neurons. The authors conclude that paragangliomas are largely benign and encapsulated and respond to simple resection. When surgically feasible, gross total removal should be the goal of surgery. When subtotal resection is necessary or when local invasion leaves a question as to completeness of tumor removal, irradiation seems mandatory although far from guaranteeing prevention of recurrence. Biopsy alone is undesirable.

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