dermatology- clin med

• Skin functions include barrier against environment, immunologic, regulation, protection from radiation, nerve sensation, injury repair, and appearance/quality of life.
• The skin consists of three layers: the Epidermis, which is made of keratinocytes, the Dermis, which contains fibroblasts, collagen & elastin fibers, and the Subcutis/hypodermis, which is made of fat.
• The Pilosebaceous Unit is found everywhere except palms, soles, top of feet, and lower lip.
• Hair follicle, hair shaft, sebaceous gland, erector pili muscle are parts of the Pilosebaceous Unit.
• Apocrine Glands (sweat glands) are found in the axillae and anogenital areas that open directly into the hair follicle.
• Macule is a primary lesion that is flat, circumscribed, non palpable, often hypo- or hyperpigmented, or other colors, and may be round, oval, or irregular in shape.
• Patch is a primary lesion that is flat, circumscribed, non palpable, often hypo- or hyper pigmented, or other colors, and may be larger than a macule.
• Papule is a primary lesion that is elevated, circumscribed, usually <1cm in diameter, and may have secondary changes.
• Plaque is a primary lesion that is elevated, circumscribed, usually >1cm in diameter, and may have secondary changes.
• Nodule is a primary lesion that is elevated, circumscribed, usually >1.5 cm in diameter, and may involve the dermis and extend to the subcutis.
• Vesicle is a primary lesion that is elevated, circumscribed, usually <1cm in diameter, and is fluid-containing, usually clear.
• Bulla is a primary lesion that is elevated, circumscribed, usually <1cm in diameter, and is fluid-containing, usually clear, and may become an erosion or ulceration.
• Pustule is a primary lesion that is elevated, circumscribed, usually <1cm in diameter, and contains purulent material (neutrophils > eosinophils), and may be infectious or sterile.