Case ReportsCrystal-storing Histiocytosis due to Massive Accumulation of Charcot-Leyden Crystals: A Unique Association Producing Colonic Polyposis in a 78-year-old Woman With Eosinophilic ColitisLewis, Jason T. MD*; Candelora, Joseph N. MD†; Hogan, Reed B. MD‡; Briggs, Frank R. MD§; Abraham, Susan C. MD*Author Information *Division of Anatomic Pathology, Mayo Clinic, Rochester, MN Departments of †Pathology §Surgery, St Dominic-Jackson Memorial Hospital, Jackson, MS ‡Department of Gastroenterology, University of Mississippi School of Medicine, Jackson, MS Reprints: Jason T. Lewis, MD, Department of Pathology, Hilton 11, Mayo Clinic, 200 First Street SW, Rochester, MN 55905 (e-mail: email@example.com). The American Journal of Surgical Pathology: March 2007 - Volume 31 - Issue 3 - p 481-485 doi: 10.1097/01.pas.0000213420.46127.9c Buy SDC Metrics Abstract Crystal-storing histiocytosis is a rare diagnosis that to date has only been associated with 2 conditions: intracytoplasmic accumulation of crystallized immunoglobulins in patients with lymphoproliferative disorders or plasma cell dyscrasias, and histiocytic accumulations of phagocytosed clofazimine, a drug used to treat lepromatous leprosy. We describe a 78-year-old woman with a past medical history of dermatologic mastocytosis and peripheral eosinophilia who presented with diarrhea and weight loss, and was found at colonoscopy to have polyposis limited to the right and transverse colon. She eventually underwent subtotal colectomy to remove the segment of polyposis. At gross examination, the colonic mucosa contained numerous polyps ranging from 1 to 7 mm which on histologic evaluation proved to represent mucosal and submucosal collections of histiocytes whose cytoplasm was distended by numerous brightly eosinophilic crystals. An intense eosinophilic infiltrate surrounded the histiocyte collections and also mildly involved the intervening colonic mucosa and superficial submucosa. Electron microscopy confirmed the presence of intracytoplasmic material identical to Charcot-Leyden crystals within histiocytes, representing the breakdown products of degranulated eosinophils. This is the first reported case of crystal-storing histiocytosis produced by massive accumulation of Charcot-Leyden crystals in eosinophilic colitis. © 2007 Lippincott Williams & Wilkins, Inc.