Acrodermatitis continua with nail involvement Diseases

Various parts of the nail unit are affected in 10-50 percent of patients with psoriasis . In less than 5 percent of the time the nails may be involved without obvious skin lesions . Psoriatic nail disease manifests as pitting, "oil spots" or "oil drop" sign, onycholysis, subungual hyperkeratosis (onychoauxis), splinter hemorrhage, onychorrhexis, Beau's lines, and onychomedesis, depending on the specific structure of the nail unit affected and severity of the involvement . Pustular psoriasis of the nail units or acrodermatitis continua starts as pustules under the nail and leads to extensive destruction of the plate .

The pathology of psoriatic nails is similar to that observed in the skin with parakeratosis, acanthosis, and inflammatory changes . Nail pitting is caused by intermittent parakeratosis of the proximal matrix. The light-brown or yellowish red discoloration of the "oil drop" sign, which is virtually pathognomonic for psoriasis , reflects deposition of glycoproteins in the nail bed with onycholysis. Onycholysis and subungual hyperkeratosis is a consequence of abnormal keratinization of the nail bed. Severe involvement of the nail matrix can lead to extensive dystrophic changes of the nail plate. Treatment of severe psoriatic nail is often unsatisfactory. We report a case of severe 20-nail psoriasis successfully treated by low dose methotrexate.