Skin - Nonmelanocytic tumors
Lymphoma and related disorders
MALT lymphoma

Author: Christopher Hale, M.D. (see Authors page)

Revised: 11 October 2016, last major update February 2011

Copyright: (c) 2003-2016,, Inc.

PubMed search: MALT lymphoma [title] skin

Cite this page: MALT lymphoma. website. Accessed March 21st, 2018.
Definition / general
  • Low grade B cell lymphoma, similar to counterparts elsewhere, that often relapses to skin and subcutaneous tissue
  • In Scottish Highlands, cutaneous B cell lymphomas are associated with Borrelia burgdorferi / Lyme disease (Am J Surg Pathol 2000;24:1279)
  • They are usually marginal zone subtype, but may be follicular center or diffuse large B cell lymphomas
  • Asian cases were not associated with Borrelia DNA, API2 - MALT1 fusion nor bcl10 mutation (Am J Surg Pathol 2003;27:1061)
Clinical features
  • Most patients relapse to skin or subcutaneous sites
Case reports
Microscopic (histologic) description
  • May resemble cutaneous lymphoid hyperplasia and cutaneous follicular lymphoma
  • Diffuse proliferation of marginal zone cells outside reactive lymphoid follicles; cells are centrocyte-like or monocytoid B cells with plasmacytic differentiation
  • No epidermal change or diffuse pattern of dermal or subcutaneous infiltration
Microscopic (histologic) images
Images hosted on PathOut server:

Marginal zone, courtesy of Dr. Mark R. Wick

Positive stains
  • B cell markers
  • Light chains are monotypic
  • B cell / T cell ratio is often 3:1 or more (hyperplasia is usually T > B, Am J Surg Pathol 1999;23:88)
  • Note: CD21+ follicles may be reactive germinal centers (CD10+, CD20+, bcl6+, bcl2-), MALT lymphoma colonized follicles (CD10-, CD20+, bcl6 variable, bcl2 variable), follicular lymphoma (CD10+, CD20+, bcl6+, bcl2+) or expanded follicular dendritic cell meshworks (bcl6-, bcl2+, Am J Surg Pathol 2001;25:732)
Negative stains