Small bowel (small intestine)
Benign tumors and tumor-like conditions
Clofazimine toxicity

Author: Hanni Gulwani, M.D. (see Authors page)

Revised: 16 February 2018, last major update August 2012

Copyright: (c) 2003-2018, PathologyOutlines.com, Inc.

PubMed Search: Clofazimine small bowel

Cite this page: Gulwani, H. Clofazimine toxicity. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/smallbowelclofazimine.html. Accessed July 22nd, 2018.
Definition / general
  • Clofazimine is drug for leprosy, Mycobacterium avium complex in HIV patients, graft versus host disease
  • Poorly soluble but orally bioavailable small molecule drug that massively accumulates in macrophages when administered over prolonged periods of time (PLoS One 2012;7:e47494)
  • May cause severe abdominal pain, red skin discoloration and ichthyosis
Case reports
Microscopic (histologic) description
  • Red crystals in frozen section with bright red birefringence but clear in routinely processed histologic sections
  • Causes histiocytosis resembling lymphoma, plasmacytosis (Am J Surg Pathol 2000;24:129)
Microscopic (histologic) images

Images hosted on other servers:

Crystal storing histiocytosis: numerous large epithelioid eosinophilic cells intermingle with a mild plasmacytic infiltrate within a fibrous stroma; at high power, cells contain numerous needle-like crystals; D: birefringence under polarized light microscopy


Mononuclear epithelioid cells are strongly CD68+ (KP1) and CD68+ (PGM1), supporting a histiocytic lineage; plasma cells are CD138+; note the weak cytoplasmic positivity in histiocytes and stronger cytoplasmic positivity in plasma cells for IgG, κ light chain and λ light chain

Electron microscopy description
  • Clear spaces with some osmiophilic bodies