B-Cell Lymphomas occurring in extra-nodal mucosal sites, often due to translocations of MALT1 or BCL10 genes.

MALT and BCL bind one another to regulate NF-kB

-All present as enlarged nontender lymph nodes

-Neoplasms of Reed-Sternberg cells and variants 

-Spread in an orderly fashion

-2/3 present as enlarged nontender lymph node

-1/3 present with symptoms related to extranodal sites

-Spread in an unordered fashion

Uses Morphology, immunophenotypic, genotypic, and clinical features

1. Precursor B-Cell Neoplasms

2. Peripheral B-Cell Neoplasms

3. Precursor T-Cell Neoplasms

4. Peripheral T-Cell Neoplasms

5. Hodgkins Lymphomas

Precursor=Immature, Peripheral=Mature

CD45

Present on all Leukocytes