Diagnosis of mastocytosis: general histopathological aspects, morphological criteria, and immunohistochemical findings

Leuk Res. 2001 Jul;25(7):543-51. doi: 10.1016/s0145-2126(01)00021-2.


An increase in mast cell (MC) numbers in hemopoietic tissues may be associated with (a) primary neoplastic MC disease (mastocytosis); (b) non-mast cell lineage myelogenous disorders (myelodysplastic or myeloproliferative syndromes and myeloid leukemias); or (c) reactive, i.e. non-clonal states (MC hyperplasia and reactive mastocytosis). However, the histologic discrimination between hyperplastic states and neoplastic MC proliferative disorders is sometimes very difficult. MC hyperplasia is characterized by a diffuse increase in mature, round or spindle-shaped, metachromatic MC that are loosely scattered throughout the tissue and do not form dense focal infiltrates, even in states of marked hyperplasia. However, loosely scattered MC are also a prominent feature of many cases of myelodysplastic syndromes and acute leukemia involving the MC lineage. In contrast, the demonstration of dense, focal and/or diffuse MC infiltrates can be regarded as indicative of primary MC disease/mastocytosis. In addition to the highly diagnostic focal MC infiltrates, mastocytosis may also present with a predominantly diffuse or a mixed (diffuse and focal) infiltration pattern. The relatively rare diffuse pattern is usually dominated by atypical, often hypogranulated or even non-metachromatic MC and is associated with the aggressive or frankly malignant subtypes of systemic mastocytosis and MC leukemia. Although the demonstration of MC infiltrates in Giemsa-stained tissue sections is still very important for the diagnosis of mastocytosis, immunohistochemical techniques using antibodies against MC-associated antigens such as tryptase or c-kit (CD117) are essential for the identification of highly atypical, hypogranulated MC, especially in MC leukemia, and for the detection of small and even minute MC infiltrates.

Publication types

  • Review

MeSH terms

  • Adult
  • Biomarkers
  • Bone Marrow / pathology
  • Carboxylic Ester Hydrolases / analysis
  • Cell Count
  • Cell Lineage
  • Chymases
  • Diagnosis, Differential
  • Digestive System / pathology
  • False Negative Reactions
  • Humans
  • Hyperplasia
  • Leukemia, Mast-Cell / diagnosis
  • Leukemia, Mast-Cell / pathology
  • Lymphoid Tissue / pathology
  • Mast Cells / chemistry
  • Mast Cells / pathology*
  • Mastocytosis / diagnosis*
  • Mastocytosis / metabolism
  • Mastocytosis / pathology
  • Myelodysplastic Syndromes / diagnosis
  • Myelodysplastic Syndromes / pathology
  • Myeloid Cells / pathology
  • Proto-Oncogene Proteins c-kit / analysis
  • Sensitivity and Specificity
  • Serine Endopeptidases / analysis
  • Staining and Labeling
  • Tryptases


  • Biomarkers
  • Proto-Oncogene Proteins c-kit
  • Carboxylic Ester Hydrolases
  • chloroacetate esterase
  • Serine Endopeptidases
  • Chymases
  • Tryptases