This chapter mainly focuses on the acute eczematous dermatitis, psoriasis, and malignant tumors of skin. The word eczema is derived from Greek, meaning “to boil over” which describes its gross appearance. Acute eczematous dermatitis is one of the most common skin disorders. Allergic contact dermatitis, atopic dermatitis, drug-related eczematous dermatitis, photoeczematous dermatitis, and primary irritant dermatitis are five types of acute eczematous dermatitis. Psoriasis is a chronic, frequently familial inflammatory dermatosis that appears to have an autoimmune basis. Psoriasis most commonly involves the skin of the elbows, knees, scalp, lumbosacral areas, intergluteal cleft, and glans penis. The typical lesion consists of a well-demarcated, pink to salmon-colored plaque covered by loosely adherent silver-white scale. Squamous cell carcinoma, basal cell carcinoma, and melanoma are various types of malignant tumors of skin, which are also provided in this chapter.