title: Idelalisib-induced colitis and skin eruption mimicking graft-versus-host disease.
abstract: BACKGROUND
  Idelalisib is a selective inhibitor of the delta isoform of phosphatidylinositol 3-kinase which was approved by the United States Federal Drug Administration in 2014 for the treatment of relapsed chronic lymphocytic leukemia and indolent non-Hodgkin lymphoma. Drug-induced injury of the gastrointestinal tract is a relatively frequent but usually under-recognized disease entity.
  
  
  METHODS
  We report the case of a 56-year-old male with a history of relapsed follicular lymphoma status post allogenic bone marrow transplant who developed severe diarrhea with a skin eruption mimicking graft-versus-host disease (GVHD) 6 months after starting idelalisib. He underwent a colonoscopy demonstrating a grossly normal-appearing colon and terminal ileum. Biopsies taken during the procedure revealed mild active ileitis, colitis, and proctitis with frequent epithelial apoptosis, and focal intra-epithelial lymphocytosis. Skin biopsies revealed sub-acute spongiotic dermatitis suggestive of either contact dermatitis or an eczematous drug reaction. Symptoms were attributed to idelalisib given their resolution with withdrawal of the drug in conjunction with the skin and colonic biopsies.
  
  
  CONCLUSIONS
  High clinical suspicion and awareness of the histological features of idelalisib-associated colitis is important to distinguish it from potential mimickers such as GVHD and infectious colitis.
authors.affiliation: Division of Gastroenterology and Hepatology, Department of Internal Medicine, Saint Louis University School of Medicine, 1402 S. Grand Blvd., St Louis, MO, 63104, USA. mbhammami@hotmail.com.
authors.forename: Muhammad Bader
authors.initials: MB
authors.lastname: Hammami
authors.affiliation: Department of Internal Medicine, Saint Louis University School of Medicine, St. Louis, MO, USA.
authors.forename: Ahmad
authors.initials: A
authors.lastname: Al-Taee
authors.affiliation: Saint Louis University School of Medicine, St. Louis, MO, USA.
authors.forename: Marshall
authors.initials: M
authors.lastname: Meeks
authors.affiliation: Division of Hematology and Oncology, Saint Louis University School of Medicine, St. Louis, MO, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Fesler
authors.affiliation: Department of Dermatology, Saint Louis University School of Medicine, St. Louis, MO, USA.
authors.forename: M Yadira
authors.initials: MY
authors.lastname: Hurley
authors.affiliation: Department of Pathology and Immunology, Washington University School of Medicine, St Louis, MO, USA.
authors.forename: Dengfeng
authors.initials: D
authors.lastname: Cao
authors.affiliation: Department of Pathology, Saint Louis University School of Medicine, St. Louis, MO, USA.
authors.forename: Jin-Ping
authors.initials: JP
authors.lastname: Lai
mesh_terms: D000970:Antineoplastic Agents / Q000009:adverse effects* / Q000627:therapeutic use; D001706:Biopsy; D003092:Colitis / Q000139:chemically induced* / Q000175:diagnosis / Q000473:pathology; D003106:Colon / Q000473:pathology; D003937:Diagnosis, Differential; D003875:Drug Eruptions / Q000175:diagnosis / Q000209:etiology* / Q000473:pathology; D006086:Graft vs Host Disease / Q000175:diagnosis*; D006801:Humans; D008224:Lymphoma, Follicular / Q000188:drug therapy; D008297:Male; D008875:Middle Aged; D011687:Purines / Q000009:adverse effects* / Q000627:therapeutic use; D052999:Quinazolinones / Q000009:adverse effects* / Q000627:therapeutic use; D012867:Skin / Q000473:pathology
chemical_list: D000970:Antineoplastic Agents; D011687:Purines; D052999:Quinazolinones; C552946:idelalisib
keywords: Drug-induced colitis; Graft-versus-host disease; Idelalisib