Lymph nodes not lymphoma
Inflammatory disorders (noninfectious)
Clofazimine induced changes

Author: Jaya Balakrishna, M.D.
Editor: Abdelsalam Sharabi, M.D.

Revised: 28 November 2017, last major update November 2017

Copyright: (c) 2003-2017, PathologyOutlines.com, Inc.

PubMed Search: Clofazimine induced changes
Cite this page: Balakrishna, J. Clofazimine induced changes. PathologyOutlines.com website. http://pathologyoutlines.com/topic/lymphnodesclofazimine.html. Accessed December 15th, 2017.
Definition / general
  • Clofazimine induced crystal storing histiocytosis
ICD-10 coding
Epidemiology
  • Rare condition in patients taking clofazimine, an antileprosy medication
Sites
  • Most commonly subcutaneous tissue, spleen, lymph nodes, liver, lung and gastrointestinal tract
Clinical features
  • Red discoloration of skin and other tissues, mass formation, lymphadenopathy
Diagnosis
  • History of clofazimine intake, biopsy
Radiology description
  • Enlarged lymph nodes, particularly intra-abdominal lymph nodes
Prognostic factors
  • Extent of involvement
Case reports
Treatment
  • Excision of affected lymph node
  • Cessation of treatment apparently does not reverse the process
Gross description
  • Enlarged lymph node with light brown to dark red discoloration
  • Fixative and solutions used for processing the specimen turn red with the crystals dissolving in them
Microscopic (histologic) description
  • Marked interfollicular plasmacytosis and histiocytes containing crystals in their cytoplasm, which are elongated with irregular edges, some forming bundles
  • Crystals are typically deep red, but depending on the fixative and processing can be clear and colorless (crystals dissolve in alcohol)
  • Crystals show bright red birefringence if polarized
  • They can be seen in extra and intracellular locations
Microscopic (histologic) images

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Diffuse eosinophilic histiocytes

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Cell death induced in macrophages by clofazimine

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Histiocytes are strongly CD68+

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Crystalline inclusions within the histiocytes

Positive stains
  • Plasma cells are highlighted by CD138 and are polyclonal by kappa and lambda light chain stains
  • Lymphocytes are mixed B and T cells and histiocytes show positive staining with CD68 and CD163
Negative stains
  • Crystals are negative for PAS and immunoglobulin heavy and light chains
Electron microscopy description
  • Transmission electron microscopy shows the empty spaces which crystals have been occupying
  • Crystals show some osmiophilic material which appear to be granular or multivesicular bodies
  • Upon higher magnification, these crystals show a multilamellar core or a lattice with elements spaced periodically
Electron microscopy images

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Elongated and rhomboid shaped dense crystals

Molecular / cytogenetics description
  • No clonal populations of cells
Differential diagnosis
  • Crystal storing histiocytosis with immunoglobulin crystals, which is usually associated with a lymphoid or plasma cell neoplasm
  • Fungi
  • Parasites
Board review question #1
    In crystal storing histiocytosis, the cell type which accumulates crystals is:

  1. Histiocytes
  2. Lymphocytes
  3. Neutrophils
  4. Plasma cells
Board review answer #1
A. The crystals in CSH in tissues get phagocytosed by histiocytes where they form collections. When these cells accumulate, they form a mass lesion.