Lymphohistiocytic tumors

MALT lymphoma

Last author update: 1 September 2012
Last staff update: 18 March 2021

Copyright: 2003-2023,, Inc.

PubMed Search: MALT lymphoma lung

Deepali Jain, M.D.
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Cite this page: Jain D. MALT lymphoma. website. Accessed March 26th, 2023.
Definition / general
  • Lymphoma of Mucosal Associated Lymphoid Tissue - a type of marginal zone lymphoma
  • Called pseudolymphoma in older literature
  • In adults, lung MALT is usually low grade, median age 68 years (range 34 - 88), often associated with autoimmune disorders, monoclonal gammopathies, hepatitis C, Helicobacter pylori gastritis
  • 44% involve mediastinal nodes
  • Usually indolent with excellent prognosis (Am J Surg Pathol 2001;25:997)
  • May recur locally, rarely transforms, few die of disease
  • 20% have monoclonal gammopathy, 30% have pleural effusions
  • Flow cytometry of tumor cells is useful in phenotyping; may even be helpful on peripheral blood
  • BALT (lymphoma of Bronchus Associated Lymphoid Tissue) is a rare, low grade, primary pulmonary MALT lymphoma
  • In pediatric HIV patients with lymphoid interstitial pneumonitis, chemokines and cytokines may recruit inflammatory cells, either representing an early stage of MALT or providing a microenvironment for the evolution of a monoclonal B-cell population (Mod Pathol 2001;14:929)
Case reports
  • Local resection for limited disease, chemoradiotherapy for advanced disease
Gross description
  • Solitary discrete mass, occasionally multiple nodules
Gross images

Contributed by anonymous
Discrete tan mass Discrete tan mass Discrete tan mass

Discrete tan mass

Microscopic (histologic) description
  • Nodular pattern of monotonous, mature lymphocytes with germinal centers that infiltrate overlying epithelium (lymphoepithelial lesions) and around vessels, pleura and alveolar septa
  • Cells may be monocytoid or resemble centrocytes
  • Also reactive plasma cells, variable fibrosis and epithelioid granulomas
  • Also colonization of germinal centers by tumor cells
  • Rarely granulomatous vasculitis
Microscopic (histologic) images

Contributed by anonymous
Lymphoepithelial lesion

Lymphoepithelial lesion

Monotonous population<br>of small-intermediate cells

Monotonous population
of small-intermediate cells

Positive stains
Negative stains
Differential diagnosis
  • Benign lymphoid aggregates / reactive disorder: architecture is preserved, associated with immunosuppression and collagen vascular disease; not monoclonal by flow cytometry or PCR (Am J Surg Pathol 2002;26:76)
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