XXXX . A clinicopathologic study of a potentially aggressive variant of @entity1653 .

@entity172 @entity1 @entity1364 @entity1420 @entity8855 @entity5 @entity146 @entity1758 @entity1653 @entity3 @entity4786 @entity2281
Since @entity1653 has only recently been recognized as a morphologic entity, its pathobiology has not been studied. Fourteen examples occurring in seven females and six males, ages 9 to 82 years (mean 29 years), were examined; one was associated with type 2 @entity4786 . Of these cases, seven (50%) were spinal-intradural (six lumbar, one thoracic), three (21%) arose in the posterior fossa (cerebellopontine angle), three (21%) were supratentorial, and one (7%) was centered upon the foramen magnum. In one case (8%), two @entity5 were considered to be independent primaries. One @entity5 (8%) appeared to show no dural attachment. Thirteen @entity5 were subject to complete study. All were composed of sheets of clear, glycogen-rich, polygonal cells forming only a few vague whorls. @entity8855 , both stromal and perivascular, was often extensive. Mitoses were rare in @entity5 . Immunohistochemistry showed vimentin and epithelial membrane antigen staining to be reactive in 100%. Stains for @entity2281 protein and CAM 5.2 were negative. @entity1420 and @entity172 receptor staining was observed in 77% and 0%, respectively. Ultrastructural study showed abundant cytoplasmic glycogen, a few cytoplasmic lumina, intermediate filaments, interdigitation of cell membranes, and desmosomal junctions. The means, medians, and ranges of @entity1364 ( @entity1364 ) and @entity1758 antigen labeling indices for nonrecurring and recurring @entity5 were 10.4%, 8.8%, 0.8-23.4% and 11%, 1.4%, 0.1-50.3%, as compared with 7.4%, 6.7%, 2.9-17.2% and 13.3%, 13.4%, 3.3-25.7%, respectively. Twelve successful DNA ploidy studies showed that 11 @entity5 (85%) were diploid and one was tetraploid; percentage S-phase determinations varied from 4 to 9% (mean 6.0%). Recurrence was noted in eight @entity1 (61%) (five of whom had multiple recurrences); there was local discontinuous spread in two cases (15%) and widespread cranial to spinal @entity3 in one case (8%). Three @entity1 (23%) are dead of disease. In summary, @entity1653 are morphologically unique, show no sex predilection, affect primarily the lumbar region and cerebellopontine angle, and despite their benign appearance, may be @entity146 , particularly intracranial examples. No close association was noted between recurrence or clinical outcome and such factors as mitotic activity, @entity1364 proliferation indices, percent S-phase determination, or DNA ploidy status. In contrast, @entity1758 proliferation indices were appreciably higher among recurring @entity5 .
