How often should blood tests be repeated to rule out systemic lupus erythematosus (SLE) in a patient positive for discoid lupus erythematosus (DLE)? — Sherry Guralnick Cohen, CRNP-F, Owings Mills, Md.

The progression of localized DLE to DLE as part of SLE has been observed. Callen noted six of 62 patients with DLE who either had (two patients) or developed (four patients) SLE or mixed connective tissue disease (Arch Dermatol. 1982;118:412-416). This is similar to Millard and Rowell, who noted SLE to develop in 6.5% of their patients with DLE (Arch Dermatol. 1979;115:1055-1058). Specific guidelines for repeating blood tests to rule out SLE in a patient with DLE have not been established; however, it has been suggested that “the tests may need to be repeated every year or so.” — Philip R. Cohen, MD (155-9)