NON-HODGKIN'S LYMPHOMA - 11/09/11
Résumé |
Pediatric lymphomas are the third most common group of malignancies in children and adolescents (after acute leukemias and brain tumors), and account for 12% of all newly diagnosed childhood cancers. Approximately 60% of pediatric lymphomas are non-Hodgkin's lymphomas (NHL), with the remainder being Hodgkin's lymphomas.110 About 500 cases are diagnosed annually in the United States, with three times as many of these patients being males than females.
Pediatric NHLs account for only about 3% of all NHLs in western countries, but their incidence steadily rises with age.140 In addition to their relative rarity, the histological spectrum of childhood NHL is also considerably narrower than that of adult NHL, as the most common types of lymphomas in adults—the low grade, relatively indolent NHLs such as follicular lymphomas—are exceedingly rare in children. Pediatric lymphomas are diffuse aggressive lymphomas with a propensity for widespread dissemination, approximately half of which are small, noncleaved cell (Burkitt's and Burkitt-like) lymphomas, about one third lymphoblastic, and the remainder large cell lymphomas. They usually present as abdominal (small, noncleaved, and many large cell lymphomas) or thoracic (lymphoblastic and some large cell lymphomas) masses, although acute presentations such as abdominal emergencies (e.g., intussusception or a syndrome resembling acute appendicitis) or symptom complexes relating to compression of upper mediastinal structures may occur. Presentations with enlarged lymph nodes are much less common than in adults.
These presentations and patterns of spread result from the origin of NHLs from the normal cells of the immune system, whose migration patterns they mimic.78, 82 To understand the pathogenesis, pathology, and clinical features of malignant lymphomas, therefore, some knowledge of the cellular composition and differentiation pathways of the normal lymphoid system is necessary.25, 82, 111 Just as the immune system can be divided into T- and B-cell compartments, NHLs fall into B- and T-cell categories. Small, noncleaved cell lymphomas are exclusively of B-cell origin whereas lymphoblastic lymphomas are predominantly of T-cell origin (precursor T-cell origin, to be precise), and large cell lymphomas may be of B- or T-cell origin.
Lymphoid neoplasms, like other neoplastic processes, arise because of genetic changes that result in altered growth and differentiation patterns of lymphoid cells. The characterization of these molecular abnormalities and an understanding of their consequences have led to new approaches to diagnosis and the detection of minimal residual disease, and also provide the basis for the future development of novel treatment approaches targeted specifically to the neoplastic cells.
In the meantime, the intensification of conventional treatment approaches by several cooperative groups in Europe and the United States, coupled with improvements in supportive care, have resulted in marked improvements in event-free survival rates, such that with these regimens approximately 90% of patients with B-cell lymphomas, and only slightly fewer with T-cell lymphomas, are cured.118 In this article the biology and treatment of the malignant NHLs of childhood and adolescence are discussed, emphasizing recent advances in the understanding of these diseases and the impact that this new understanding will have on their diagnosis and management.
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| Address reprint requests to Aziza Shad, MD, Division of Pediatric Hematology Oncology, Georgetown University Medical Center, 3800 Reservoir Road, NW, Washington, DC 20007 |
Vol 44 - N° 4
P. 863-890 - août 1997 Retour au numéro
Article précédent
- DIAGNOSIS AND TREATMENT OF CHILDHOOD ACUTE MYELOGENOUS LEUKEMIA
- David H. Ebb, Howard J. Weinstein
- HODGKIN'S DISEASE
- Melissa M. Hudson, Sarah S. Donaldson
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