Ultrastructural morphometric analysis of lesional skin: mast cells from patients with systemic and nonsystemic mastocytosis.

Lesional skin mast cells from some patients with mastocytosis appear morphologically atypical; however, these subjective differences have not been quantified. Herein we describe an objective method for analyzing cutaneous mastocytosis mast cells by a combination of morphometric analysis and electron microscopy. By this technique, lesional mast cells from patients with adult systemic mastocytosis had a significantly larger mean cytoplasmic area (53.3 microns2), nuclear size (20.4 microns2), and granule diameter (0.81 micron) when compared with mast cells from adults with nonsystemic mastocytosis (36.3 micron 2, 15.4 microns2, and 0.67 micron, respectively) and normal age-matched control subjects (34.4 microns2, 14.1 microns2, and 0.67 micron, respectively). Lesional skin mast cells from infants with nonsytemic mastocytosis were very similar to adult nonsystemic mastocytosis mast cells but differed by several parameters from mast cells in adults with systemic involvement. This study demonstrates that there are quantitative differences between lesional skin mast cells from patients with systemic mastocytosis and those with nonsystemic disease.