MALT lymphoma, also called
extranodal marginal zone lymphoma of the MALT, arises in a number of epithelial tissues; this most area are the gastric, ocular, bowel, pulmonary and salivary glands.
Pulmonary
extranodal marginal zone lymphoma with massive crystal storing histiocytosis.
Findings on pathologic examination were consistent with
extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma).
Extranodal marginal zone lymphoma of mucosa associated lymphoid tissue (MALT lymphoma) does not typically have a nodular appearance unless the neoplastic cells colonize reactive follicles.
The concept of extranodal marginal zone lymphoma of MALT type has revolutionized the criteria for the morphologic diagnosis of an extranodal lymphoma, specifically those lymphomas dominated by small lymphocytes.
No separate classification for gastrointestinal lymphomas is offered by the World Health Organization (WHO), although extranodal marginal zone lymphoma of MALT (including immunoproliferative small-intestinal disorder) and enteropathy-associated T-cell lymphoma form 2 distinct categories among the mature B-, T- and natural killer (NK)-cell neoplasms.
In addition, some NHLs, such as mycosis fungoides and extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT), occur predominantly or entirely in extranodal sites.
Extranodal Marginal Zone Lymphoma of Mucosa-Associated Lymphoid Tissue (MALT Lymphoma): sIG+ (IGM or IGA or IGG), sIGD-, cIG-/+, panB+, [CD5.
Although a number of B-cell lymphoproliferative processes (either primary splenic or secondary involvement) were considered in the differential diagnosis, including chronic lymphocytic leukemia/small lymphocytic lymphoma, mantle cell lymphoma, lymphoplasmacytoid lymphoma (immunocytoma), follicular lymphoma,
extranodal marginal zone lymphoma, and hairy cell leukemia, the histologic findings as well as immunophenotypic analysis were felt to be most in keeping with a splenic marginal zone B-cell lymphoma.
2) Of these, only an estimated 2,670 (5%) were
extranodal marginal zone lymphomas.
Nodal marginal zone lymphoma is a rare, biologically and clinically heterogeneous entity (2) that shares morphologic and immunophenotypic characteristics with
extranodal marginal zone lymphomas of the mucosa-associated lymphoid tissue type and with splenic marginal zone lymphomas.
23,24) However, care must be taken to meet the exact definition of the disease as the majority of cases of extranodal lymphoma occurring at MALT sites, and composed of small lymphocytes and plasma cells, are
extranodal marginal zone lymphomas (see later discussion).
