what are diseases of the skin
acanthosis - an abnormal but benign thickening of the prickle-cell layer of the skin (as in psoriasis) acanthosis nigricans, keratosis nigricans - a skin disease characterized by dark wartlike patches in the body folds; can be benign or malignant. acne - an inflammatory disease involving the sebaceous glands of the skin; characterized by papules or pustules or comedones.