Non‐endemic erythrodermic pemphigus foliaceus: a case with delayed diagnosis and response to rituximab

Abstract

Pemphigus foliaceus (PF) is an autoimmune blistering disorder with two clinical variants: sporadic and endemic PF [ 1 ] . Pemphigus foliaceus typically presents with crusted lesions on seborrheic areas of the scalp, face and trunk [ 1 ] . In the majority of cases the target antigen is desmoglein-1 (160 kDa), an intercellular adhesion protein that connects epidermal keratinocytes [ 2, 3 ] . Erythroderma accounts for about 6 % of PF cases, which are usually cases of fogo selvagem (endemic pemphigus foliaceus) [ 4 ] . Exfoliative erythroderma can occur during non-endemic PF that does not respond to treatment, and is even more unusual [ 5 ] . These cases of erythrodermic PF may initially be misdiagnosed as psoriatic erythroderma or staphylococcal scalded skin syndrome (SSSS). Immunofl uorescence is mandatory to establish the correct diagnosis and guide appropriate management [ 2, 3 ] . Here we present a rare case of erythrodermic PF that was misdiagnosed for months, refractory to classic treatment procedures and only responsive to rituximab. Α 53-year-old woman visited our department due to exfoliative dermatitis and ectropion. She initially developed a papular eruption accompanied by some tiny pustules on her trunk. This exanthema gradually progressed to erythroderma over a period of nine months. In the meantime, the patient was admitted to another hospital (fi ve months beforehand) with the diagnosis of SSSS. At that point a complex intravenous antibiotic treatment resulted in partial improvement. Since then the patient has been treated with various antibiotics as well as low doses of systemic prednisone and cyclosporine without complete remission of erythroderma. At admission to our department (Figure 1 a, b), tissue and blood samples were taken for histology and immunofl uorescence investigation. Histology revealed acantholysis in the granular layer of the epidermis (Figure 2 ). Immunofl uorescence techniques, both direct and indirect, gave positive results and revealed an intercellular reaction with IgG and C3. High titers of circulating anti-DSG-1 autoantibodies were also detected (>200). The molecular weight of DSG-1 (160 kDa) was captured by Western blot. Pemphigus foliaceus was confi rmed by all the above procedures as the cause of erythroderma in our patient. After a multidisciplinary collaboration, we treated the patient with a combination regimen of plasmapheresis and prednisolone in intravenous pulses. A signifi cant improvement was observed after seven weeks in hospital, and the patient was released (Figure 1 c). Two months later, while the patient was still treated with 40 mg prednisone and 100 mg azathioprine and had no erythroderma, many circinate erythematosquamous lesions were observed on the face and