Diagnostic Relevance of the Lupus Band Test

Before interpreting a positive DIF finding in a presumed case of LE, several reasons for false-positive or false-negative results must be taken into account and excluded. Linear deposits or dust-like particles mostly containing IgM and/or C3 can be seen along the DEJ in a great variety of other inflammatory skin diseases - often in facial or chronically sun-exposed skin (Table 22.2). Continuous deposits of IgG, however, are usually not found in such cases and are conspicuous of true LE. In sun-protected nonlesional skin, DIF findings are always negative in biopsy specimens from patients with the diseases listed in Table 22.2. False-negative results can be obtained when fresh lesions or lesions from patients treated topically or systematically with corticosteroids or immunosuppressants are biopsied (Dahl 1983).

There is common understanding that a positive predictive or confirmatory value of the LBT in lesional skin for the diagnosis of LE is lower than the negative predictive value since a negative DIF finding in lesional skin is rather uncommon, whereas a (false-)positive DIF finding can be found in many other inflammatory skin diseases (Table 22.2). In nonlesional skin, however, a positive LBT result has a far higher positive predictive value than a negative one and clearly points to a diagnosis of LE, especially when deposits of IgG are present. Otherwise, the LBT, in lesional and unin-volved skin, has only little value for the distinction between DLE, SCLE, and SLE. For this purpose, serologic tests with demonstration of subtype-specific antinuclear antibodies are much more sensitive and specific (Conrad et al. 2000).

100 Hair Growth Tips

100 Hair Growth Tips

100 Hair Growth Tips EVERY Balding Person Should Know. This Report

Get My Free Ebook


Post a comment