First Description of a Primitive Neuroectodermal Tumor Arising in the Nose
Figure 2
(a) Lobules of small, round, blue cells, separated by fibrous septa underneath an intact squamous epithelium (hematoxylin-eosin stain, objective original magnification ×5). (b) Higher magnification revealing tumor cells with scant, ill-defined cytoplasm and well-defined nuclei with coarse chromatin pattern (objective original magnification ×40), with a proliferation index superior to 15% (Ki-67 stain at the upper right corner). (c) Immunohistochemical membranous cytoplasmic stain for CD99 (objective original magnification ×40). (d) Immunohistochemical stain for S-100 (objective original magnification ×5).
