The significance of the 'dust-like particles' pattern of immunofluorescence. A study of 66 cases.

Subacute cutaneous lupus erythematosus (SCLE) is a marker of a unique subset of lupus erythematosus patients. A 'dust-like particles' direct immunofluorescence (DIF) staining pattern, which consists of fine granular particles of immunoglobulin(s) scattered through the epidermis and the cellular infiltrates of the dermis, was reported to be specific for SCLE. In this study, we assessed the real specificity of this staining pattern, which had not yet been evaluated. We systematically searched for the dust-like particles staining pattern among the 4374 skin biopsy specimens submitted for direct cutaneous immunofluorescence during a 7-year period (1989-96). The corresponding patient records were reviewed. Dust-like particles were observed in 66 samples originating from 60 patients. Only 53% of the patients had SCLE. The remaining patients had systemic lupus erythematosus with visceral involvement (17%), discoid lupus erythematosus (3%), mixed connective tissue disease (2%). Sjögren syndrome (2%) and other diseases. Eighty-five per cent of the patients had connective tissue disease. Seventy-seven per cent of the patients were positive for antinuclear antibodies, but only 36% were positive for anti-Ro (SSA) antibodies. This study shows that the dust-like particles staining pattern is not specific for SCLE, but is highly suggestive of connective tissue disease. The nature of the antigen responsible for the immunoglobulin deposition and the prognostic significance of this DIF pattern remain to be established.