Solid (from the English solid – firm) call not hemopoietic tumors, that is the tumors which developed not from cells of the hemopoietic system. Solid tumors can be high-quality and malignant, but is more often, speaking about them, mean malignant tumors.
Among solid tumors of children's age brain tumors are most widespread. Also solid tumors of nervous tissue (neuroblastoma), kidneys (nefroblastom), bones (an osteosarcoma, Ewing's sarcoma, etc.), soft tissues (a rhabdomyosarcoma, etc.) are known, to a liver (hepatoblastoma), an eye (retinoblastoma), some other bodies and fabrics. Some of these tumors – such as neuroblastoma, the retinoblastoma or a nefroblastoma – occur almost only at children; others can arise at any age, but at children have the features. Many tumors which are found at early children's age have the embryonal nature, that is arise from formative cells.
Cancer tumors (carcinomas) of various bodies characteristic of adult age, practically do not occur at children.