To the Editor.—
The article by Fabré et al1 on the presence of granular deposits of immunoglobulin at the basement membrane zone of normal sun-exposed skin is valuable in pointing out some of the limitations of direct immunofluorescence for the diagnosis of lupus erythematosus. However, their results differ from those of prior studies in which granular deposits of immunoglobulin at the basement membrane zone have been reported to be present in sun-exposed skin in fewer than 5% of normal individuals.2A likely explanation for the discrepancy between prior studies and that by Fabré et al is that the latter obtained the biopsy specimens of normal sun-exposed skin from the neck. This is in contradiction to the sun-exposed sites that usually undergo a biopsy in systemic lupus erythematosus, which are the extensor surface of the forearm or the deltoid area of the arm.2-5 It has been demonstrated that
Bystryn J. Limitations of Direct Immunofluorescence. Arch Dermatol. 1992;128(2):271–272. doi:10.1001/archderm.1992.01680120147024
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