ACQUIRED IMMUNOBULLOUS DISEASE - A CUTANEOUS MANIFESTATION OF IGM MACROGLOBULINEMIA

Waldenstrom's macroglobulinaemia has been associated with a variety of cutaneous manifestations. We report a patient with an acquired bullou s disorder associated with skin fragility and IgM kappa paraprotein. I mmunofluorescence studies demonstrated bright linear deposition of IgM along the basement membrane zone (BMZ), around dermal blood vessels a nd on arrector pill muscles. Weak keratinocyte cell surface staining w ith IgM was also noted, There was no deposition of complement or other immunoglobulins. Indirect immunofluorescent studies revealed a circul ating IgM anti-BMZ antibody (titre 1/200), which bound to both the roo f and the Boor of a 1 mol/l NaCl split skin substrate, Immunoblotting analysis of the patient's serum, with both epidermal and dermal extrac ts, was negative. Treatment with a combination of prednisolone and aza thioprine was successful, We suggest that this IgM kappa paraprotein h as a low affinity for an undefined epitope within the lamina lucida, w hich has produced a subepidermal bullous disorder associated with skin fragility.