Clinical record

A 44-year-old Samoan man presented in 2004 with a blistering skin rash affecting his face, trunk and upper limbs (Figure, A). There was no mucosal involvement and a positive Nikolsky sign (the production of a blistering lesion on applying pressure to non-affected skin) was demonstrated. Skin biopsy revealed acantholysis and cleft formation within the superficial layers of the epidermis, confirming a diagnosis of pemphigus foliaceus. Direct immunofluorescence testing of a perilesional skin biopsy specimen revealed deposition of IgG and C3 in the intercellular cement substance of all layers of the epidermis. Indirect immunofluorescence testing, using a monkey oesophagus substrate, demonstrated a high titre of autoantibodies in the patient’s serum.

The condition failed to respond to prednisone combined with other immunosuppressive agents, including azathioprine, cyclosporin and mycophenolate mofetil. In late 2006, the patient developed a significant flare of the disease, associated with Staphylococcus aureus superinfection, which resulted in a lengthy hospital admission. Plasmapheresis was instituted, with clinical benefit and a concomitant decrease in antipemphigus antibodies to undetectable levels. However, the plasmapheresis was complicated by Citrobacter koseri sepsis due to colonisation of the intravenous catheter. Despite treatment of the sepsis and reinstitution of immunosuppression with prednisone and mycophenolate mofetil, the pemphigus flared again, accompanied by a dramatic increase in the titre of antipemphigus antibodies.

The hospital drug committee approved off-label use of two courses of rituximab (375 mg/m2). This resulted in rapid resolution of the lesions and a marked decrease in antipemphigus antibodies. Depletion of B cells was evident on immunophenotyping of peripheral blood mononuclear cells, and the corticosteroid dose was subsequently weaned to 0.1 mg/kg/day. Nine months after treatment with rituximab, the patient’s clinical condition remained stable (Figure, B).