Mixed connective tissue disease syndrome.

Fifteen patients with epidermal nuclear staining on direct immunofluorescence of normal skin and high titer serum antibody to ribonuclease-sensitive extractable nuclear antigen (ENA) had diffuse nonscarring and focal alopecia, abnormal pigmentation, swollen hands with sclerodactyly, and chronic cutaneous lupus erythematosus (LE) as the most common dermatologic features. Direct immunofluorescence of normal, unexposed skin revealed a particulate ('speckled') epidermal nuclear staining pattern in all 15 patients and subepidermal immunoglobulin deposits in 5. Ribonucleoprotein antibodies in high titer are associated with this characteristic type of epidermal nuclear staining. These findings provide easily detectable markers for a less aggressive subset of LE characterized by distinctive clinical and laboratory features consistent with mixed connective tissue disease.