Except for urticaria pigmentosa (fixed reddish brown maculopapular lesions) and cutaneous mastocytosis, mast-cell biopsy findings are difficult to identify via standard hematoxylin and eosin staining (Figure 1), and in many cases, specific pathologic features such as crypt distortion, mucin depletion, cryptitis, abscesses, granulomas, thickened collagen bands, shortened villi, or excessive eosinophils/lympocytes are not seen in mast cell–related disease.6 Consultation with a pathologist is essential to ensure that an appropriate evaluation is performed. The excess of mast cells can be evaluated via immunohistochemical analysis for CD117, mast-cell tryptase, or Giemsa staining (Figure 2).
