PMC331414_01
H&E features of the tumour (original magnification 10x; inset 40 x): sheets of monotonous cells infiltrating vessels (small arrow) even near the capsule (long arrow). Homer-Wright rosettes were common (inset).
1471-2407-4-3-1.jpg
PMC331414_01_1471-2407-4-3-1.jpg
F1
It presented different patterns, with cohesive lobules or rosettes and perivascular pseudo-rosettes or, in some areas, spindle cellular elements (fig. 1).
Immunoperoxidase for CD99 (10x) showed the tumor composed of small round cells with round nuclei and scant cytoplasm arranged in cohesive lobules. There are spindle cellular elements with diffuse CD99 cytoplasmic staining. Inset a (40x) shows Homer-Wright type rosettes positive for CD99.
1471-2407-4-3-2.jpg
PMC331414_01_1471-2407-4-3-2.jpg
F2
The immunohistochemical evaluation revealed a diffuse CD99 positivity in the cytoplasm of the neoplastic cells (fig. 2); tumoral cells were also visible in the vascular lumens (fig. 3).