LAUSR

Pemphigus foliaceus (PF) is a variant of pemphigus, a chronic autoimmune bullous disease. The separation of the epidermis in PF is caused by autoantibodies to desmoglein 1 which is mostly located in the upper epidermis. Unlike pemphigus vulgaris, the oral mucosa is not involved in PF due to less expression of desmoglein 1 in the mucous membrane. DIF of the skin specimen is regarded as the gold standard for the diagnosis of pemphigus and normally shows intercellular deposition of IgG and/or C3 in the epidermis. Interestingly, in addition to the skin, DIF of plucked anagen and telogen hair of pemphigus patients also demonstrates similar findings of intercellular deposition of immunoreactants. This can be explained by the fact that the structure of the outer root sheath of the hair corresponds to that of the epidermis. Positive DIF of plucked hair has been shown for all variants of pemphigus, namely pemphigus vulgaris, PF, pemphigus erythematosus, and pemphigus vegetans [1]. Positivity was observed irrespective of the presence of scalp lesions and in patients with only mucosal involvement [1]. The use of plucked hair for DIF is non-invasive. This might help in the diagnosis of pemphigus vulgaris, with a sensitivity of 85-91% [2]. Furthermore, in the assessment of immunological remission, DIF of plucked hair showed a sensitivity of 80% and a specificity of 48-70% when using conventional skin DIF as the gold standard [3, 4]. Compared to skin biopsy, hair plucking is less invasive and easier and cheaper to perform. It might be interesting to combine DIF of plucked hair in both the standard approach for diagnosis and monitoring of pemphigus patients.