Nail changes in alopecia areata: light and electron microscopy.

Fragments of nail keratin removed with tweezers from patients suffering from alopecia areata were examined using light microscopy and electron microscopy. The results obtained from these two techniques show nail changes which are slits, cupuliform dips of the upper edge and parakeratosis, under light microscopy; vacuoles, depletion of keratin fibers, and electron-dense fibrillary deposits, under electron microscopy. These changes predominate in the nail plate with a maximum in the upper part while the subungual keratin is preserved. A serious disorder of the matrix keratinization is probably the source of this preferential localization. To determine whether it is a disorder of the keratin fibers themselves or rather of the interfilamentary matrix and especially of the filaggrin system will require further biochemical and immunological studies.