Skin Diseases by Layer

DISEASES AFFECTING STRATUM CORNEUM

• Icthythyois: hyperkeratosis over the entire body, giving the skin a scaly or fish like appearance.
  
  
   
  • Icthyosis Vulgaris: most common (75%) and underdiagnosed
    • Abnormal retention of S. corneum, may see hypo- or agranulosis.
      • Skin is usually thick, and smelly. Often children will go to school and the teachers will yell at them for not washing and then they will go home and scrub until their skin bleeds, but alas the next day the teacher yells and the kids tease calling them smelly. This leads to children dropping out of school and eventually becoming homeless, so lets all be aware of this conditions and educate our patients & school teachers.
    • Genetic link – autosomal dominant
• Dermatophytes: includes tinea capitis (head), manum (hand), pedis (foot) cruris (groin), corporis (body) and is caused by fungi which infects the skin.
• Candida albicans  is a yeast which infects skin, distinguished from dermatophytes by a pustular reaction

DISEASES AFFECTING THE STRATUM MALPIGHI

• Dermatitis
  • Can have a psychological effect
  • Pompholyx (palms and soles) Hand Eczema
    • Aka: dishydrosis: On the palms and soles there are lots of eccrine glands and it was originally thought that this condition was due to a malfunction of these glands causing dehydration
    • Most commonly seen in people who do manual labor, especially involving water and cleaning solvents; however there doesn’t have to be a cause
    • Characterized: vesicular, crusted, and severe dermatitis
    • Major cause of disability in industry

    

     

• Stasis dermatitis:
  • Usually found on legs
  • Caused by abnormal vasculature due to stasis of blood
  • Occurs on below the knee, over the medial malleolus
  • Often the 1^st sign of leg ulcer development
  • Seen a lot in nursing homes
• Contact Dermatitis
  • Caused by contact with an irritant
  • Will combine with a protein on the surface, and is antigenic resulting in am immune reaction in which inflammatory mediators are involved.

• Aka: Allergic contact dermatitis
  • Commonly seen with metal allergies (nickel). If you have to wear the metal for some reason, coat the metal with clear nail polish.
  • Also seen with leaves (outdoors) especially the rhus species of poison ivy, poison oak, and poison sumac
  • Patch testing: in which the substance is rubbed on the skin to see if a reaction occurs, is used to determine allergen
  • Other examples:
    •  a women who could not attend outdoor functions bc the reaction of the sunlight with her perfume was allergenic (phytophotodermatitis)
    •  A male who was allergic to his wife’s contraceptive cream

• Impetigo
  • Bacterial infection of the superficial part of the S. Malpighii
  • Bacteria (staph or strep) will get under the S. corneum and multiply. This attracts neutrophilsto the area in an attempt to get rid of the bacteria. The skin is also proliferating during this time, making lots of immature cells that the bacteria can grow in.
  • Edema (including PMNs) between the S. corneum and S. malpighii will occur resulting in crusting (pustule)
  • May also see blisters involving hair follicles: carbuncles & furnucles
  • Remember: this is not a systemic problem (probably will not have a fever)! The individual is not sick! BUT treat w/ systemic antibiotics
  • This is sometimes referred to as leprosy (but its not the real leprosy)
• Cellulitis or Erysipelas
  • Seen with a strep infection
  • Rapid spread of erythema due to lytic enzymes produced by the bacteria
  • Characterized: widespread, swollen, hot, markedly edematous lesion
    • Often can see lymphatic streaks
      • Note: an infection with staph causes a deep, localized, pus filled nodue that occurs in a hair follicle, and is termed a furuncle. If multiple furnucles (carbuncle)
• Janeway’s Nodes:
  • Patients with subacute bacterial endocarditis (bacterial vegetations on the heart valves) may have vegetation form an emboli which will cause infarction under the nails, resulting in dark spots under the nails
• Erythema Migrans (lyme disease)
  • Caused by a tick bite (Deer tick) which probably got infected from a mouse
  • Have an expanded lesion, with hyperpigmentation.
• Figured Erythema
  • Stay for days
• Erythema Marginala
  • Transient

  Back to the Integumentary System Index