Non-Hodgkin's lymphomas in childhood. A clinicopathologic and epidemiologic study in Finland

All cases diagnosed in Finland as non-Hodgkin's lymphoma (NHL), Hodgkin's disease or histiocytosis X in children younger than 15 years in 1953 to 1973, according to the Finnish Cancer Registry, were reexamined histologically. Only 55% of the cases originally diagnosed as NHL were regarded as such at reexamination. The others were mainly malignant nonlymphatic tumors such as neuroblastoma and different kinds of sarcomas. Seventy-two NHLs were diagnosed in 50 boys and 22 girls. The corrected age-specific incidence rate was 0.32/10(5). The most common histologic types were Burkitt's lymphoma (BL) (30 cases), lymphoblastic lymphoma (LBL) (26), large cell lymphomas (LCL) (six), and non-Burkitt's lymphoma (n-BL) (three). There were marked differences between BL and LBL in the course of the disease: BL was extranodal in 83%, LBL only in 4% (mediastinum was regarded as nodal); BL showed initial abdominal or pelvic involvement in 60% whereas LBL showed none; BL had initial mediastinal involvement in 7%, and LBL had it in 62%; all patients with LBL died whereas 23% of those with BL survived. Other types of NHL resembled BL in their course of disease. Patients with initial tonsillary involvement appeared to have the best prognosis and patients with mediastinal involvement the poorest. The importance of accurate histologic classification is emphasized. It appears to be most important to differentiate LBL from other types of NHL.