Pemphigus vulgaris as the first manifestation of multiple myeloma: a case report.

BACKGROUND: The association between pemphigus and malignancy has been well documented for decades but an association between pemphigus vulgaris and multiple myeloma is unusual. We report a case of pemphigus vulgaris revealing multiple myeloma.

CASE PRESENTATION: A 55-year-old Malagasy man, with no significant past medical history, presented with bullous and erosive skin lesions involving his trunk and scalp for the last 2 months. He had no mucous membrane involvement. A diagnosis of pemphigus vulgaris was made on skin biopsy and direct immunofluorescence of perilesional skin revealing immunoglobulin G deposition in the intercellular spaces in the epidermis. In an enzyme-linked immunosorbent assay, his serum autoantibody index against desmoglein-1 and 3 was found to be 112 RU/mL and 34 RU/mL respectively. Serum immunoelectrophoresis showed a monoclonal gammopathy with a markedly elevated immunoglobulin G level (2880 mg/dL) in association with a lambda free light chain. Bone marrow aspirate showed 6% plasma cell infiltration. Further investigations, including creatinine blood test and whole body radiographic examinations, showed that he had initially clinical stage I multiple myeloma of the immunoglobulin G-λ type. Six months later, bone tomography revealed vertebral compression fractures of the thoracic and lumbar spine that correlated with his back pain topographically. Anti-myeloma treatment including melphalan and prednisone led to an immediate decline in monoclonal immunoglobulin G concentration. Skin and hematologic remission were maintained for 12 months.

CONCLUSIONS: Absence of mucosal involvement, lack of vacuolar degeneration at the interface, and absence of apoptotic, dyskeratotic keratinocytes ruled out paraneoplastic pemphigus in our case. Pemphigus vulgaris should be considered even if possible underlying disease for which paraneoplastic pemphigus is recognized is present.