Making The Diagnosis

The diagnosis of ALL is usually established by a bone marrow examination from which morphologic assessment, as well as immunophenotypic, cytogenetic, and molecular analyses, may be obtained. Patients presenting with circulating lymphoblasts may also have the diagnosis established by performing these analyses on a peripheral blood sample. ALL and lymphoblastic lymphoma are considered to be the same disease biologically. When patients present with extensive blood and bone marrow involvement with more than 25% blasts, the disease is categorized as ALL. For patients having disease confined to mass lesions and having less than or equal to 25% blasts in the bone marrow, the diagnosis of lymphoblastic lymphoma is used.39 For patients with lymphoblastic lymphoma, the diagnosis may be established by a biopsy of an involved lymph node(s) or mass lesion(s). An adequate amount of tissue should be obtained to perform the appropriate immunophe-notypic, cytogenetic, and molecular analyses.

CNS disease may be detected by a lumbar puncture for CSF cytologic and flow cytometric analyses. Usually, this procedure is not performed initially when there are circulating lymphoblasts in the peripheral blood, as this may theoretically introduce disease into the CSF. Alternatively, a traumatic lumbar puncture may contaminate the CSF specimen with blood containing leukemic lymphoblasts, which could then result in a false positive test for CNS leukemia.

0 0

Post a comment