Extrarenal rhabdoid tumor

Figure 1. By light microscopy, two of the characteristic features of extrarenal rhabdoid tumors are the considerable amount of eosinophilic staining cytoplasm and the displacement of the nucleus to one pole of the tumor cell. Ultrastructurally, the nucleus (N) is displaced by the accumulation of intermediate filaments (arrows). The latter leads to an increased cytoplasmic protein content, which inturn accounts for the prominent pink staining with eosin. X2,000.

Figure 2. A whorl-like accumulation of intermediate filaments (arrow)—generally vimentin, but cytokeratins can be co-expressed—within which are a few mitochodria. The increased content of intermediate filaments displaces the remaining cytoplasm as well as the nucleus (N) peripherally. X3,000.

Figure 3. Higher magnification of the intermediate filaments. The fairly regular spacing and sinuous form of the filaments is often seen with vimentin. The filaments displace the mitochondria (top) and surround a partial section through the nucleus (bottom). X20,000.

Extrarenal Rhabdoid Tumor