Small bowel (small intestine)
Benign tumors and tumor-like conditions
Reviewer: Hanni Gulwani, M.D. (see Reviewers page)
Revised: 19 November 2012, last major update August 2012
Copyright: (c) 2003-2012, PathologyOutlines.com, Inc.
● 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
● 11 year old boy with severe enteropathy 2 years after beginning clofazimine treatment for graft versus host disease after bone marrow transplant (J Pediatr 2001;138:574)
● 45 year old woman with lepromatous leprosy (Indian J Pathol Microbiol 2004;47:281)
● 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)
Crystal-storing histiocytosis: numerous large epithelioid eosinophilic cells intermingle with a mild plasmacytic infiltrate within a fibrous stroma; at high power, cells contain numerous needlelike crystals; D-birefringence under polarized light microscopy
Mononuclear epithelioid cells are strongly CD68+ (KP1) and CD68+ (PG-M1), 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
End of Small bowel (small intestine) > Benign tumors and tumor-like conditions > Clofazimine toxicity
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