Clofazimine-induced crystal-storing histiocytosis producing chronic abdominal pain in a leprosy patient

Clofazimine-induced crystal-storing histiocytosis is a rare but well-recogn ized condition in the literature. Besides the common reddish discoloration of the skin, clofazimine produces gastrointestinal disturbances-sometimes s evere abdominal pain, prompting exploratory laparotomy, because pathologic and radiologic findings can produce diagnostic difficulties if the patholog ic changes caused by clofazimine are not recognized. The authors report suc h a case in a leprosy patient to emphasize the importance of history taking , the radiologic abnormalities of the small intestine, and the pathologic f indings in small intestine and lymph node biopsies. Clofazimine crystals' a re red in the frozen section and exhibit bright-red birefringence. However, they are clear in routinely processed histologic sections because they dis solve in alcohol and organic solvents. They also appear as clear crystal sp aces during electron microscopic study, but some osmiophilic bodies can be observed. Histiocytosis caused by clofazimine crystals produces infiltrativ e lesions in radiologic studies mimicking malignant lymphoma or other infil trative disorders. Associated plasmacytosis in the histologic sections can simulate lymphoplasmacytic lymphoma or multiple myeloma with crystal-storin g histiocytosis. With the knowledge of this rare condition caused by clofaz imine, appropriate management to avoid an unnecessary laparotomy is possibl e.