The CD 99 test is a very abstract test being done. It is done to substantiate the level of CD 99 pseudoautosomal gene. The identification is done to diagnose Small Round Cell Tumor and the treatment done forth. It is also called IHC Marker CD 99 Immunohistochemistry Blood, CD 99 Count, and IHC Marker CD 99. As the test is related to the presence of a substance in blood, the blood samples are taken in it. CD 99 Immunohistochemistry Biopsy Tissue is performed on a sample of biopsy tissue, whereas CD 99 Immunohistochemistry Bone Marrow is performed on a sample of bone marrow.