In Hodgkin’s lymphomas [80], osteosarcomas [18,22], pancreatic tumors [11], gallbladder carcinomas, gastric carcinomas [15,17] and in pulmonary neuroendocrine tumors of diverse histological types [81], CD99 is expressed at low levels, whereas the molecule is present in the respective normal tissues. The gene discussed is CD99; the disease is osteosarcoma.