Pigmented purpuric dermatosis in mixed cryoglobulinaemia associated with rheumatoid arthritis and hepatitis C infection.

A 47-year-old Japanese woman presented with a 3-year history of rash on her lower legs. The eruption tended to worsen in winter. She had suffered from rheumatoid arthritis (RA) for 6 years and hepatitis C virus (HCV) infection for 4 years. Upon physical examination, punctate purpura and pigmentation were scattered over her lower legs and their coalescence formed irregular red-brown patches (Fig. 1A). Routine laboratory tests were within their normal ranges. Antinuclear antibodies, antineutrophil cytoplasmic antibodies and cryoglobulins were not detected. Rheumatoid factor was 451 IU/ml and HCV RNA was 750 k copies/ml. Morning stiffness and erosive polyarthritis were noted. Histological examination of the skin lesion demonstrated a moderate perivascular lymphocytic infiltrate with extravasated erythrocytes (Fig. 1B). Some siderophages were seen in the dermis. There was no specific deposition in direct immunofluorescence. From those results, we made a probable diagnosis of chronic pigmented purpura and treated her with topical corticosteroids.