The diagnosis of a lymphoma is made by excisional biopsy, a surgical procedure in which a portion of the enlarged lymph node or other suspected area (known as a "mass") is surgically removed so that the cells in the mass can be examined. The tissue is viewed under a microscope to determine whether specific types of cells are present. The site of the biopsy is determined largely by the location of the mass and whether the site is easily accessible for surgery. (Removal of fluid by a procedure called fine needle aspiration is not recommended because this procedure often does not provide enough information to confirm a diagnosis of a lymphoma.)
After a biopsy is performed and the diagnosis of a lymphoma is made, additional diagnostic testing will be performed to determine the type, grade, and stage of the lymphoma. The majority of lymphomas diagnosed in children and adolescents are of the high-grade (or fast growing) type.
