Pyoderma gangrenosum associated with paroxysmal nocturnal hemoglobulinuria and monoclonal gammopathy.

Pyoderma gangrenosum developed in a man with a five-year history of paroxysmal nocturnal hemoglobinuria and monoclonal gammopathy. He had multiple walnut sized ulcers on his back and extremities, plasma IgM-k type M-protein and low erythrocytic CD55 expression. This is an extremely rare association. However, clonal expansion of plasma cells and chimeric expression of hematopoietic cell glycosylphosphatidylinositol (GPI)-anchored proteins may represent somatic mutations of hematopoietic stem cells in PG as well as PNH. PNH is based on abnormalities in the GPI-anchor formation on various hematopoietic and non-hematopoietic cells. Since the GPI-anchored proteins have pleiotropic functions in complement mediated cell lysis, leukocyte motility, and coagulation systems, the present case may indicate the possible involvement of a GPI-anchored protein abnormality in the pathogenesis of PG.