Low Grade Malignant Non-Hodgkin's Lymphomas and Peripheral Pleomorphic T-Cell Lymphomas in Childhood - A BFM Study Group Report

: Non-Hodgkin's lymphomas (NHL) are classified as low or high grade malignant lymphomas of either B or T cell origin. Cells of low grade malignant NHL (LG-NHL) of B cell type represent either follicular or postfollicular, cells of LG-NHL of T cell type postthymic maturation stages in the lymphoid differentiation pathway. LG-NHL often fail to undergo long-term complete remission or cure in adults, no matter what type of conventional therapy is applied. In three pediatric therapy studies frequency and probability of continuous complete remission (pCCR) were studied for LG-NHL and peripheral pleomorphic T-cell lymphomas (PTCL). Of 432 evaluated patients only six children (1.4%) were qualified as LG-NHL. LG-NHL of T cell type were diagnosed in three children (one T-zone lymphoma, two PTCL of small cell type), LG-NHL of B cell type in another three cases. Two children presented with nodular type of centroblastic/centrocytic lymphoma (CB/CC), one with lymphoplasmocytoid type of immunocytoma (IC). In addition to the two patients with low grade malignant PTCL, there have been also four children with high grade malignant PTCL. The analysis showed that there was not significant difference for event free survival of children with LG-NHL and HG-NHL, respectively (pCCR: 0.63 and 0.82, p = 0.29). In contrast, when comparing high and low grade PTCL versus all other types of childhood NHL (non-PTCL), a significant difference seems to exist (pCCR for PTCL: 0.44, for non-PTCL: 0.83; p = 0.02). However, for further concisive conclusions more patients are needed for evaluation.