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 removed, so that the cells in the mass can be examined. The tissue is viewed under a microscope to determine whether cells specific to the various types of lymphoma 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 the diagnosis of a lymphoma.)
Once a biopsy is performed and the diagnosis of a lymphoma is determined, additional testing will be performed to determine the type, grade, and stage of the lymphoma. The majority of lymphomas diagnosed in children and adolescents are high grade.
