The most common nodal malignancies in children are of lymphoid lineage, although mesenchymal, histiocyte/macrophage), and metastatic tumors may also present initially as node-based disease.
Immunophenotypic analysis is always required for an accurate diagnosis, and cytogenetic studies in non-Hodgkin lymphomas are fre-quently helpful.
Like its benign counterparts, malignant adenopathy can be categorized morphologically by the architectural changes seen in affected lymph nodes.
The most widely accepted current classifi cation from the World Health Organi-zation (WHO) adopts a diagnostic and biologically meaningful approach based on the lineage of the malignant cell.
Within each lineage of the WHO classifi cation, distinct diseases are defi ned based on a combination of clinical, morphologic, immunophe-notypic, and molecular genetic features.
The vast majority of pediatric cases of non-Hodgkin lymphoma fall into one of the four categories:
diffuse large B-cell lymphoma
Burkitt lymphoma
lymphoblastic lymphoma (T-cell or B-cell)
anaplastic large cell lymphoma.
Indolent lymphomas composed of small lymphocytes (e.g., small lymphocytic lymphoma, marginal zone lymphoma, mantle cell lymphoma, follicle center cell lymphoma) are extremely rare in children, and they should be diagnosed with caution.
Other Rare B-Cell Lymphoma in Children
Two small B-cell lymphomas are worthy of note but only rarely seen in children: follicular lymphoma and nodal marginal zone lymphoma.
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