The basics -- Diagnostic clues and "need to know" items -- Lichenoid reaction pattern -- Psoriasiform reaction pattern -- Spongiotic reaction pattern -- Vesiculobullous reaction pattern -- Granulomatous reaction pattern -- Vasculopathic reaction pattern -- Disorders of epidermal maturation and keratinization -- Disorders of pigmentation -- Disorders ofcollagen -- Disorders of elastic tissue -- Cutaneous mucinoses -- Cutaneous deposits -- Diseases of cutaneous appendages -- Cysts, sinuses, and pits -- Panniculitis -- Metabolic and storage diseases -- Miscellaneous conditions -- Cutaneous drug reactions -- Reactions to physical agents -- Cutaneous infections and infestations -- Bacterial and rickettsial infections -- Spirochetal infections -- Mycoses and algal infections -- Viral diseases -- Protozoal infections -- Marine injuries -- Helminth infestations -- Arthropod-induced diseases -- Tumors of the epidermis -- Lentigines, nevi, and melanomas -- Tumors of cutaneous appendages -- Fibrous tumors and tumor-like proliferations -- Tumors of fat -- Tumors of muscle, cartilage, and bone -- Neural and neuroendocrine tumors -- Vascular tumors -- Cutaneous metastases -- Cutaneous non-lymphoid infiltrates -- Cutaneous lymphomatous and leukemic infiltrates.