Chapter 61 - Disorders of Skin Integrity & Function

• rashes are temporary eruptions of the skin due to childhood diseases, heat, diaper irritation, or drug-induced reactions
• a lesion is a traumatic or pathologic loss of normal tissue continuity, structure, or function
• rash types:

  • blanched (white)
  • erythematous (reddened)
  • hemorrhagic or purpuric (containing blood)
  • pigmented
• fungi are free-living plant-like organisms that are single celled and composed of long filaments/hyphae
• fungi live on dead keratinized cells of the epidermis (enzyme to digest keratin)
• fungi causes superficial skin scaling, nail disintegration, or hair breakage
• primary bacterial infections are superficial and include impetigo and ecthyma
• impetigo appears as a small vesicle or pustule or as a large bulla on the face or elsewhere
• impetigo is commonly caused by staphylococci or beta-hemolytic streptococci
• ecthyma is an ulcerative form of impetigo, is less common, and is caused by Ritter disease/staphylococcal scalded skin syndrome
• secondary bacterial infections are deep cutaneous infections including infected ulcers and cellulitis
• cellulitis affects the dermis and subcutaneous tissue
• cellulitis is caused by a bacterial infection that enters the skin if compromised (ulcer, wound) and causes inflammation to occur
• cellulitis can enter the lymphatic system and spread
• cellulitis is usually caused by:

  • group A beta-hemolytic streptococcus
  • streptococcus pneumoniae
  • staphylococcus aureus
• cellulitis is commonly found in the legs (calves, thighs), feet, and hands
• risk factors of cellulitis:

  • compromised skin (e.g., athlete's foot)
  • older age
  • compromised defences (e.g., HIV/AIDS)
• manifestations of cellulitis:

  • erythema
  • warmth
  • edema
  • fever
  • pain (inflammatory reaction)
• treatment for cellulitis:

  • mild = oral antibiotics
  • severe = IV antibiotics (if hospitalized)
• complications of cellulitis:

  • lymphangitis
  • gangrene
  • sepsis
• in HPV, verrucae (warts) are common benign papillomas (thickening of stratum spinosum and corneum)
• HPV warts disappear when immunity develops, but this may take years
• removal of HPV warts is common (e.g., liquid N2, salicylic acid, duct tape)
• in type 1 HSV, the organism is spread by respiratory droplets or by direct contact with infected saliva, persisting in a latent state in the dorsal root ganglia
• type 2 HSV results in genital herpes
• herpes zoster/shingles are localized vesicular eruptions distributed over a dermatomal segment of the skin, resulting from reactivation of latent varicella-zoster virus from initial infection that has persisted in the dorsal root ganglia
• sebacenous glands secrete holocrine sebum, which is a mixture of lipids
• puberty increases the activity of sebaceous glands, which is driven by androgens
• types of acne:

  • noninflammatory
  • inflammatory
  • acne vulgaris
• noninflammatory acne is characterized by comedones
• whiteheads are comedones that are pale, slightly elevated papules with no visible orifice
• blackheads are comedones that are coloured plugs by melanin
• comedones are plugs of material that accumulate in sebaceous glands that open to the skin sirface
• inflammatory acne is characterized by papules, pustules, nodules, and, in severe cases, cysts
• inflammatory acne is developed to develop from the escape of sebum into the dermis and the irritating effects of the fatty acids contained in the sebum
• acne vulgaris is a chronic inflammatory disease of the pilosebaceous unit
• in acne vulgaris, excessive sebum allows growth of P. acnes which have lipases that break down free fatty acids and produce acne inflammation
• acne vulgaris is most common in adolescents and young adults
• topical treatments for acne vulgaris are designed to keep the pore open and limit bacterial growth, including retinoids and benzoyl peroxide
• benzoyl peroxide works by oxidizing bacterial proteins by free radical production from metabolism at the skin