PRIMARY MEDIASTINAL LARGE-CELL LYMPHOMA IN CHILDREN - A REPORT FROM THE CHILDREN CANCER GROUP

Malignant lymphomas arising in the mediastinum account for approximate ly 60% of all mediastinal tumors in children; two-thirds are non-Hodgk in's lymphomas and one-third represent Hodgkin's disease. In contrast to adults, in children mediastinal non-Hodgkin's lymphomas are usually synonymous with lymphoblastic lymphoma, and nonlymphoblastic lymphoma s are rare. We describe nine children with primary mediastinal large c ell lymphoma who were treated with the Children's Cancer Group protoco l CCG-503, a randomized phase III protocol for disseminated nonlymphob lastic lymphoma. Histologic subclassification revealed three immunobla stic lymphomas, three multilobated large cell lymphomas, one with clea r cell features, and two large noncleaved cell lymphomas. Sclerosis, o f variable degrees, was seen in all tumors. Immunophenotyping revealed all tumors to be of B cell lineage. Thymic epithelial cells could be demonstrated utilizing antibody to keratin, in two of nine patients, s uggesting that some of the tumors are of thymic origin. None of the pa tients had central nervous system or bone marrow involvement. It appea rs that primary mediastinal nonlymphoblastic lymphomas in children, al though much less common, are similar to those seen in adults. These tu mors must be differentiated from lymphoblastic lymphoma and Hodgkin's disease, as the therapeutic approach may depend on histologic subtype. Primary mediastinal large cell lymphoma in children appears curable w ith aggressive treatment in the majority of patients.