Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (362 page)

   Lipid storage diseases—Gaucher disease, Niemann-Pick disease, and many more

   Amyloidosis

   Sarcoidosis

   Metastatic disease

   Developmental anomalies

   Multitransfused patients

   In many cases of splenomegaly, the spleen’s ability to engulf blood cells is increased (hypersplenism), resulting in mono-, bi-, or pancytopenias.

   
LYMPHOMAS
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NON-HODGKIN LYMPHOMAS

   Definition

   Non-Hodgkin lymphomas are neoplasms of lymphoid tissues comprising numerous variants. They are a heterogeneous group of distinct disorders, mostly unrelated to one another, with a spectrum of histologic grades and clinical behavior. The present classification, as updated by the WHO in 2008, recognizes three categories of lymphoid neoplasms: B-cell, T-cell, and NK cell lymphomas, and separately Hodgkin lymphoma and plasma cell disorders. Among the non-Hodgkin lymphomas, most are derived from B cells. The present classification is based on currently available morphologic, immunophenotypic, and genetic techniques, with an attempt to correlate the various types with their clinical behavior. The latter is utilized as a guide for predicting prognosis and therapy in the International Prognostic Index.

   Many issues remain unresolved, and the 2008 WHO classification represents evolving concepts. Rapidly evolving genomic technologies, which include gene rearrangement and microarray techniques, reveal multiple subtypes of different molecular etiologies, clinical evolution, and response to therapy, all within the presently accepted types of lymphomas.

   In addition, studies of microRNA (miRNA) (small noncoding RNAs that orchestrate many aspects of cell physiology and their deregulation is often linked to distinct neoplasms) have demonstrated clusters, such as 17–92 overexpressed in a variety of B-cell lymphomas.