Mast cell leukemia presenting as urticaria pigmentosa; report of a case.

Abstract

The concept of urticaria pigmentosa as a benign dermatologic syndrome needs revision. Generalized organ involvement may be present and in this case, with demonstration of the tissue mast cells in the peripheral blood and bone marrow, we chose to classify it as a form of leukemia. The differentiation between tissue mast cells and blood basophils is emphasized. Post-mortem examination revealed generalized infiltration of the body organs with tissue mast cells. Heparin and histamine determinations on frozen, post-mortem specimens of liver showed a concentration of approximately 100-times normal. Tissue mast cells were demonstrated in the peripheral blood. The factors associated with the hemorhagic diathesis are reviewed.