title: Mast cell tryptase and microphthalmia transcription factor effectively discriminate cutaneous mast cell disease from myeloid leukemia cutis.
abstract: BACKGROUND
  Cutaneous mast cell disorders are uncommon, but a subset, especially mastocytoma and mast cell leukemia, can histologically mimic myeloid leukemia cutis. Our objective was to employ a panel of cytochemical and immunohistochemical markers to determine which ones would be most useful in separating these two entities.
  
  
  METHODS
  We stained 17 cases of cutaneous mast cell disease and 20 cases of myeloid leukemia cutis with Giemsa, toluidine blue, or pinacyanol erythrosinate (PE), as well as with antibodies against mast cell tryptase, microphthalmia transcription factor (MiTF), CD117 (c-kit), myeloperoxidase, CD43, CD25, CD2, and CD68.
  
  
  RESULTS
  Mast cell tryptase and MiTF emerged as highly sensitive and specific markers for mast cell disease in this context, as both antibodies stained all cases of mast cell diseases but none of myeloid leukemia cutis. Although CD117 stained all cases of mast cell disease, it also stained 2 of 18 cases of myeloid leukemia cutis. PE appeared to be specific for mast cell disease, as 11 of 12 cases stained with this marker, compared with 0 of 18 cases of myeloid leukemia cutis.
  
  
  CONCLUSIONS
  Our results show that mast cell tryptase and MiTF are equally effective in distinguishing mast cell disease from myeloid leukemia cutis.
authors: Department of Pathology, Stanford University Medical Center, Stanford, CA 94305, USA. sundram@stanford.edu
authors: Uma N
authors: UN
authors: Sundram
authors: Yasodha
authors: Y
authors: Natkunam
mesh_terms: D015703:Antigens, CD / Q000378:metabolism; D015214:Antigens, Differentiation, Myelomonocytic / Q000378:metabolism; D018801:CD2 Antigens / Q000378:metabolism; D003937:Diagnosis, Differential; D006801:Humans; D007150:Immunohistochemistry; D053645:Interleukin-2 Receptor alpha Subunit / Q000378:metabolism; D007951:Leukemia, Myeloid / Q000175:diagnosis* / Q000378:metabolism; D051917:Leukosialin / Q000378:metabolism; D008407:Mast Cells / Q000378:metabolism / Q000473:pathology*; D034701:Mastocytosis, Cutaneous / Q000175:diagnosis* / Q000378:metabolism; D051739:Microphthalmia-Associated Transcription Factor / Q000378:metabolism*; D019009:Proto-Oncogene Proteins c-kit / Q000378:metabolism; D053802:Tryptases / Q000378:metabolism*; D000097382:CD68 Molecule
chemical_list: D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D018801:CD2 Antigens; D053645:Interleukin-2 Receptor alpha Subunit; D051917:Leukosialin; D051739:Microphthalmia-Associated Transcription Factor; D019009:Proto-Oncogene Proteins c-kit; D053802:Tryptases; C067980:CD68 antigen, human; D000097382:CD68 Molecule