P19 Diagnostic conundrums in paraneoplastic pemphigus

Abstract Paraneoplastic pemphigus (PNP) is a subset of pemphigus, a group of autoimmune blistering skin disorders. A 51-year-old man presented with paraneoplastic pemphigus associated with a hepatic neoplasm. He described an epigastric mass and associated mucositis affecting the orogenital mucosae, as well as the sclerae. Both computed tomography and magnetic resonance imaging demonstrated a 14-cm mass arising from the left lobe of the liver. A liver biopsy showed features of an atypical spindle-cell neoplasm, but a definite diagnosis was not possible. A diagnostic skin biopsy was taken from his outer lip mucosae. Histology showed surface ulceration with an acute inflammatory infiltrate, lichenoid lymphoplasmacytic infiltrate with focal basal vacuolar change, degenerate keratinocytes and adjacent suprabasal acantholysis and spongiosis. Perilesional direct immunofluorescence (DIF) was negative; however, indirect immunofluorescence (IIF) showed intercellular IgG antibodies on transitional epithelium with a high titre of 1 : 800 to rat bladder. These finding were consistent with the suspected clinical diagnosis of paraneoplastic pemphigus. The patient was commenced on oral prednisolone 1 mg kg−1 daily. Topical therapy included budesonide mixed with sweetener applied to the oral mucosae. Following this, a trial of 3 days of intravenous methylprednisolone along with 2% cocaine mouthwash, triple mouthwash (betamethasone, doxycycline and nystatin) and Dermovate® ointment was commenced, with improvement noted in pain, haemorrhage and ulceration. Intravenous immunoglobulin was administered preoperatively. The patient was subsequently transferred to a specialist centre for hepatobiliary surgery and listed for debulking of the liver mass. Postoperatively, he had plasmapheresis, with a noted reduction in mucosal ulceration and significant improvement in pain. Chemotherapy with doxorubicin and ifosfamide was initiated thereafter. PNP is a severe autoimmune blistering disorder characterized clinically by flaccid blisters and erosions. Although much is yet to be understood regarding the pathophysiology of PNP, studies show that the development of autoantibodies to the plakin family and desmogleins 1 and 3 play a particular role in its pathogenesis. In addition to autoantibodies, CD8+ T cells have also been shown to contribute to the development of PNP. In adults, the majority of cases are associated with an underlying haematological malignancy and, rarely, a solid-organ tumour. DIF findings include IgG and C3 deposition along the intercellular and basement membrane zones, while IIF detects autoantibodies to proteins found in transitional or stratified squamous epithelium. As in our case, reports have shown that the DIF can be negative, with one study showing a positive DIF in only 41% of cases. This case highlights the complex diagnostic and treatment challenges practitioners face when dealing with PNP and the patients it affects.