MALT lymphoma

Mediastinum
Hematopoietic / dendritic
MALT lymphoma

Author: Hanni Gulwani, M.B.B.S.

Topic Completed: 1 December 2012

Revised: 4 December 2019

Copyright: 2003-2019, PathologyOutlines.com, Inc.

PubMed Search: MALT lymphoma mediastinum

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Table of Contents

Cite this page: Gulwani H. MALT lymphoma. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/mediastinumMALT.html. Accessed December 9th, 2019.

Definition / general

Very rare in thymus, < 20 cases reported

Clinical features

May arise without underlying autoimmunity (Lung 2011;189:461); these cases often involve males or older patients (Leuk Lymphoma 2011;52:2276)

Case reports

36 year old woman with Sjögren syndrome and coexisting thymic and gastric MALT (Arch Pathol Lab Med 2000;124:770)
63 year old woman with possible connective tissue disease (Hum Pathol 2000;31:255)
Patient with Sjögren syndrome and cryoglobulinemia (Pathology 2009;41:701)

Gross description

Centered in thymus

Microscopic (histologic) description

Clusters of centrocyte-like lymphoid cells in lymphoepithelial lesions mixed with mature lymphocytes and lymphoid follicles with reactive germinal centers
Also plasma cells
Variable microcysts
Early MALT cases in patients with thymic lymphofollicular hyperplasia and myasthenia gravis or connective tissue disease have ill defined lymphoid follicles with sheets of centrocyte-like B cells disrupting the medullary epithelial cytokeratin network

Microscopic (histologic) images

Images hosted on other servers:

Thymic tumor

Positive stains

CD20, CD45, CD79a, monotypic immunoglobulin light chain; variable BCL2 and CD10

Negative stains

CD5, CD10, CD23, CD43, CD99, BCL6, TdT

Electron microscopy description

Nuclei with irregular protrusions or blebs
No intercellular junctions, no cytoplasmic filament bundles, neurosecretory granules, synaptic vesicles, microtubules, basal lamina, cytoplasmic processes or primitive sarcomeres

Molecular / cytogenetics description

Trisomy 3 may play a role in lymphoma development (Pathol Int 2012;62:93)
Thymic MALT lymphomas have a characteristic pattern of chromosomal aberrations that may be similar to those of other autoimmune associated MALT lymphomas
Monoclonal IgH rearrangement present (Am J Clin Pathol 2002;117:51)