A refractory rash in a seborrheic distribution

Abstract

A 70-year-old man presented to our clinic in April, 2014, with a 4 month history of painful, pruritic rash involving the scalp, face, chest, and back. He had a history of colon cancer and deep venous thrombosis. A biopsy sample of the rash had been interpreted as eczema, but he had had only minimum improvement with short courses of both topical and systemic corticosteroids and antibiotics. Examination showed a healthy-looking man with erythematous papules and plaques displaying cornfl akelike scale in a seborrheic distribution (fi gure). Oral and ocular mucosae were normal. Previous serological studies, including antinuclear antibody (ANA), complement, and serum protein electrophoresis, were normal. We did lesional punch biopsy for routine histology (appendix) and perilesional punch biopsy for direct immunofl uorescence (fi gure). Clinicopathological fi ndings were diagnostic of pemphigus foliaceus. Pemphigus foliaceus is a rare autoimmune bullous disease characterised by pathogenic autoantibodies against desmoglein-1 (a desmosomal protein) that cause disruption of intercellular adhesion between keratinocytes in the epidermal granular layer (acan tholysis). This results in fragile bullae that rupture easily to form erosions with characteristic scale crust. Pemphigus foliaceus often begins on the upper body in a seborrheic distribution, but progresses to widespread involvement or erythroderma if not appropriately treated. Pruritus and burning are common and can be exacerbated by UV exposure. Unlike pemphigus vulgaris, pemphigus foliaceus is rarely associated with mucosal involvement. Diagnosis is made with biopsies for routine histology and direct immunofl uorescence. Pemphigus foliaceus typically arises in middle age and can be drug-induced, such as by penicillamine and angiotensin-converting enzyme inhibitors. An endemic form, Fogo Sevelagem (“wild fi re”), occurs in South America and has been linked with exposure to black fl ies. Before eff ective treatment was available pemphigus foliaceus fatality reached 60% due to dehydration and sepsis. Rituximab, an anti-CD20 monoclonal antibody, has recently gained favour as treatment of choice for pemphigus foliaceus and other autoimmune bullous diseases because of relatively high rates of induced remission compared with classic treatments. We prescribed 30 mg prednisolone daily and rituximab (375 mg/m2 intravenously once weekly for 4 weeks) for our patient, and triamcinolone 0·1% cream twice daily. At follow-up 2 months after treatment with rituximab most skin lesions were healed and we could reduce prednisolone to 20 mg daily (appendix). He will be followed up every 3 months until prednisolone is tapered off completely.