CLINICAL HISTORY
A 22-year-old Hispanic male presented with painless hematuria, which resolved with antibiotic therapy. Three months later, he developed severe abdominal pain. The patient had an unremarkable past medical history.
LABORATORY DATA
Noncontributory.
ANCILLARY STUDIES
A renal angiogram showed a right renal mass mainly involving the superior pole (Figure 1).
On abdominal computerized tomography scanning, the tumor appeared to extend through the right renal vein into the inferior vena cava (Figure 2).
GROSS PATHOLOGY
The pateint underwent right radical nephrouriterectomy with removal of a thrombus from the inferior vena cava. Gross examination of the 640 gm kidney revealed a poorly demarcated, firm mass occupying the superior pole of the kidney. The mass measured 12.9 x 8.0 x 5.0 cm (Figure 3). The cut surface of the mass was tan-white to gray with diffuse areas of necrosis and focal areas of hemorrhage. The tumor involved approximately 85% of the renal parenchyma, but the capsule was intact. The tumor extended into the renal pelvis and vein.
MICROSCOPIC PATHOLOGY
Hematoxylin and eosin-stained sections revealed loosely cohesive sheets of small round to slightly oval cells. The cells had ill-defined borders; small amounts of pale-staining cytoplasm; and darkly staining, round or oval nuclei with high nuclear-to-cytoplasmic ratio and inconspicuous nucleoli. There were one to two mitotic figures per high power field. Extensive areas of necrosis were also identified. Scattered poorly to well-formed rosette-like structures with a central solide eosinophilic core were present (Figure 4 and Figure 5).
Immunohistochemical staining showed positive reactivity with CD99 (MIC 2, p30/32) (Figure 6), neuron-specific enolase (NSE), s-100, and focal positivity for vimentin. Keratin, CD57 (Leu-7), synaptophysin, chromogranin, glial fibrillary acidic protein (GFPA), neurofilament, desmin, and CD45 (leukocyte common antigen; LCA) were all negative. |
