title: Well-differentiated systemic mastocytosis showed excellent clinical response to imatinib in the absence of known molecular genetic abnormalities: A case report.
abstract: BACKGROUND
  Well-differentiated systemic mastocytosis (WDSM) is a rare, recently recognized provisional subvariant of systemic mastocytosis (SM). We report a case of WDSM that showed excellent clinical and cutaneous response to imatinib in the absence of known molecular genetic abnormalities.
  
  
  RESULTS
  We present a 24-year-old woman with childhood onset of skin manifestations that progressed to mediator-related systemic events, and a gastrointestinal tract mastocytoma. A subsequent bone marrow examination showed WDSM. Treatment with imatinib resulted in complete resolution of cutaneous lesions and systemic symptoms, which relapsed with the discontinuation of the drug. Targeted next-generation sequencing-based mutation analysis did not demonstrate any mutations in the coding regions of KIT or other genes commonly associated with myeloid neoplasms.
  
  
  CONCLUSIONS
  The diagnosis of WDSM is challenging in the absence of spindle-shaped mast cells, CD2 or CD25 expression, and KIT D816 mutation. This case illustrated the need for recognizing this unique variant of SM for diagnostic and therapeutic implications.
authors.affiliation: Department of Hematopathology, The University of Texas MD Anderson Cancer Center, Houston, TX Department of Pathology, The First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, China Department of Leukemia, The University of Texas MD Anderson Cancer Center, Houston, TX.
authors.forename: Lanshan
authors.initials: L
authors.lastname: Huang
authors.forename: Sa A
authors.initials: SA
authors.lastname: Wang
authors.forename: Sergej
authors.initials: S
authors.lastname: Konoplev
authors.forename: Carlos E
authors.initials: CE
authors.lastname: Bueso-Ramos
authors.forename: Beenu
authors.initials: B
authors.lastname: Thakral
authors.forename: Roberto N
authors.initials: RN
authors.lastname: Miranda
authors.forename: Elias
authors.initials: E
authors.lastname: Jabbour
authors.forename: L Jeffrey
authors.initials: LJ
authors.lastname: Medeiros
authors.forename: Rashmi
authors.initials: R
authors.lastname: Kanagal-Shamanna
mesh_terms: D000970:Antineoplastic Agents / Q000627:therapeutic use; D001706:Biopsy; D004252:DNA Mutational Analysis; D004273:DNA, Neoplasm / Q000235:genetics*; D005260:Female; D006801:Humans; D000068877:Imatinib Mesylate / Q000627:therapeutic use*; D008407:Mast Cells / Q000473:pathology*; D034721:Mastocytosis, Systemic / Q000175:diagnosis* / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D019009:Proto-Oncogene Proteins c-kit / Q000235:genetics* / Q000378:metabolism; D055815:Young Adult
chemical_list: D000970:Antineoplastic Agents; D004273:DNA, Neoplasm; D000068877:Imatinib Mesylate; D019009:Proto-Oncogene Proteins c-kit