Afflictions of a Vestigial Appendage

Inflammatory processes affecting the nail matrix under the posterior nail fold cause the production of a dystrophic nail. Most commonly the inflammation is due to external trauma from manipulation of the posterior nail fold during manicuring or from constant exposure to irritants as in the case of housewife's eczema. The posterior nail fold is or has been inflamed, and the nail dystrophy corresponds with the period of inflammation (Fig 1). The process is limited to the affected nails and avoidance of trauma or exposure leads to prompt cure. Much more puzzling are those cases in which nail dystrophy (ridging, pitting, lysis) which arises at the nail matrix is due to an inflammatory process which is part of a more widespread skin disease. The inflammation may be practically unobservable since it originates from within the nail matrix or its supplying vessels. Although psoriasis is the most common cause of these defects