Lymphoma and plasma cell neoplasms
B cell lymphoma subtypes
Marginal zone lymphoma - MALT-type

Author: Nikhil Sangle, M.D. (see Authors page)

Revised: 3 April 2017, last major update February 2011

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PubMed Search: marginal zone lymphoma MALT-type

See also MALT - Primary sites
Cite this page: Marginal zone lymphoma - MALT-type. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/lymphomaMALT.html. Accessed September 20th, 2017.
Definition / general
  • Common low grade lymphoma that emulates Peyer patches of terminal ileum
Epidemiology
  • Associated with Sjogren syndrome, and possibly other chronic inflammatory diseases of salivary gland like lymphoepithelial sialadenitis (Am J Surg Pathol 2001;25:1546)
  • Associated with Hashimoto thyroiditis, Helicobacter pylori gastritis, Chlamydia psittaci, Campylobacter jejuni, possibly Hepatitis C virus or Borrelia burgdorferi infection
Sites
  • Stomach, bowel, salivary glands, lung, thyroid, lacrimal gland, conjunctiva, bladder, kidney, skin, soft tissue, thymus, breast
  • Occasionally bone marrow (20%) and spleen
  • GI tract most common (50% of all cases); within GI tract, stomach is most common (85%, Gastroenterology 1992;102:1628)
Clinical features
  • Most common primary extranodal lymphoma; slightly more common in women
  • B cell neoplasm of mucosal and nonmucosal extranodal sites that interacts with epithelium and reactive germinal centers
  • Usually localized (70%) and possibly curable by surgery, radiation or antibiotics
  • Disseminated disease is usually refractory to chemotherapy
  • Indolent course; median survival is 8 years; late relapse in 30% at same site or other extranodal sites
  • Rare transformation to large cell lymphoma, which has sheets of large cells and may have Reed-Sternberg like cells
  • Includes cases previously designated "pseudolymphoma" or extranodal lymphoid hyperplasia
  • May be associated with Waldenström macroglobulinemia (Am J Clin Path 2001;116:683)
  • Serum paraprotein (M-component) is present in up to 30% cases, particularly those with plasmacytic differentiation (Clin Cancer Res 2004;10:7179)
CD5+ Tumors
  • Associated with disseminated lymphoma, often in head and neck, responding poorly to treatment
  • Must rigorously exclude other B cell lymphomas
  • Case report of 87 year old woman with breast tumor (Hum Pathol 2003;34:1065)
Gross description
  • Multiple lesions are common
Microscopic (histologic) description
  • Architectural effacement by atypical centrocyte-like cells (small cleaved follicular cells with abundant cytoplasm), that infiltrate around reactive B cell follicles in a marginal zone distribution with spread into the interfollicular area
  • May invade epithelial structures to form lymphoepithelial lesions; cells are at various stages of B cell differentiation including monocytoid B cells, small lymphocytes, plasma cells, centroblasts and immunoblasts in small numbers
  • May have follicular colonization of neoplastic cells resembling follicular lymphoma
Microscopic (histologic) images

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Low grade

Low grade with transformation and crystalline inclusions

High grade tumors

Positive stains
  • CD19, CD20, CD22, CD79a, surface Ig, cytoplasmic Ig in plasma cell component, BCL10
  • Variable CD11c, variable BCL2, variable monoclonal light chain expression
  • Note: plasmacytoid cells may be negative for B cell markers but are strongly immunoreactive for kappa or lambda
Negative stains
Molecular / cytogenetics description
  • t(11;18)(q21;q21): API2 and MALT1 (50%): associated with aggressive disease and poor response to antibiotics
  • t(14;18)(q32;q21): IgH and MALT1: described in nongastric extranodal MALT lymphomas; indistinguishable from IgH / BCL2 by cytogenetics; associated with other karyotypic abnormalities including various trisomies
  • t(1;14)(p22;q32): BCL10 and IgH (% unknown): inactivates the "pro-apoptotic" BCL10 protein; associated with advanced MALT
  • t(1;2)(p22;p12): BCL10 and Ig Kappa
  • Trisomy 18 is also common; trisomy 3 is present, whole or partial in 26 - 55%
  • Multiple lesions often have 1 - 3 neoplastic clones (Mod Pathol 2001;14:957)
  • Low grade lesions often are BCL6 negative, but have BCL6 mutations by PCR
Differential diagnosis