Clinical, haematological, and radiological features of children presenting with lymphoblastic mediastinal masses.

During 1968-1978, 68 children presented in six centres in the United Kingdom with lymphoblastic mediastinal masses. The disease was classified as acute lymphoblastic leukaemia (ALL) in 49 children whose bone marrow aspirates contained > 20% lymphoblasts, and as lymphoma (Sternberg lymphosarcoma - LS) in 19 with < 20% marrow infiltration. Male predominated in both groups, and children with ALL had more visceromegaly and lymphadenopathy, lower haemoglobin levels and platelet counts, and higher white cell counts. The most common chest x-ray finding in both groups was a nonspecific anterior mediastinal mass, but the appearances varied considerably and could be classified into three categories, which are illustrated. Pleural effusions were present in 44%. Cell surface-marker studies showed T cell characteristics in 14 of the 17 patients tested. Response to treatment and complications, such as central nervous system (CNS) and testicular relapse, were similar in ALL and LS, and were related to the size of the initial tumour load. Median remission lengths were 37 weeks for ALL and 89 weeks for LS patients. Leukaemic transformation occurred in 47% of LS children. Compared with the outcome in ALL children without mediastinal mass, the results of treatment were poor, regardless of the protocol used, and prophylactic therapy to the CNS reduced the frequency of, but did not eliminate, CNS disease.