Pitting

Pits result from small areas of abnormal keratinization of the proximal nail matrix that produce foci of parakeratotic cells in the superficial nail plate. They appear as small punctate depressions of the superficial nail plate, which progress distally and often become more evident with nail growth . Deep and irregularly distributed pits are seen in psoriasis and atopic dermatitis; geometric and superficial pits are typical of alopecia areata