1. Principles of Dx
   1. Initial Assessment
      1. ask, look and think!
      2. give up preconceived dx
   2. What is the cause?
      1. Infectious
      2. Infestation
      3. Sun
      4. AI
      5. Internal dz
         1. cancers
      6. Iatrogenic
      7. Hormonal
      8. Drugs
         1. alleries
         2. side effects
      9. Allergies
         1. nickle
   3. Hx
      1. Where?
      2. When did it first appear?
         1. hx of atropy (atopic dermatitis/eczema)
      3. Has it spread? changed location?
      4. How does it feel?
      5. Has the appearance changed?
      6. Does anything make it worse or better?
         1. cleaning supplies (contact dermatitis)
         2. sun
            1. better
            2. psoriasis
            3. worse
            4. lupus
      7. Have you treated it w. anything?
      8. Other Systemic dzs
         1. DM, Candida, tinea, hep C, IBD
   4. ROS
      1. Organ Involvement
      2. Concomitant sx
   5. FHx
      1. Atopy
      2. AI
   6. SHx
      1. STDs
         1. syphilis
         2. gonorrhea
         3. herpes
   7. PE
      1. Examine ALL skin areas
         1. include
            1. mucus membrane
            2. Hair, scalp, nails
      2. Palpate lesion(s)
      3. Skin scraping
         1. 15 blade
      4. Woods lamp
2. Primary Morphology (lesion type)
   1. Macule
      1. flat
         1. non-palpable color change
      2. <10 mm
      3. variable shape
   2. Papule
      1. elevated
      2. palpable
      3. <10 mm
   3. Plaque
      1. elevated
         1. plateau-like
            1. like a raised macule
      2. irregular borders
   4. Nodule
      1. firm papule
         1. palpable
            1. extends into dermis or subQ tissue
      2. Tumors
         1. large nodules
            1. >10 mm
   5. Vesicle
      1. fluid-filled blister
      2. <10 mm
   6. Bullae
      1. vesicle
      2. >10 mm
   7. Pustule
      1. elevated lesion containing pus
   8. Urticaria
      1. aka
         1. wheals or hives
      2. transient
      3. elevated lesion
      4. red, raised
         1. no interuption of the skin line
      5. dt
         1. edema
   9. Scale
      1. accumulation of epithelium
      2. dry
         1. whitish
      3. slough off
      4. you can have a scaly plaque
   10. Erosion
       1. loss of epidermis
       2. excoriation
          1. linear erosion
          2. usu dt scratching
   11. Ulcer
       1. deep Erosion
       2. bleed and scar
   12. Petechiae
       1. non-blanchable
          1. indicative of vascular prob
       2. small
       3. punctuate foci of hemorrhage
   13. Purpura
       1. larger hemorrhage
       2. bruises or ecchymosis
   14. Atrophy
       1. paper-thin
          1. looks winkled and dry-appearing skin
   15. Scar
       1. fibrous tissue replacement after injury
   16. Telangiectasia
       1. dilated superficial blood vessels
3. Secondary Morphology/Configuration
   1. Shape
      1. Linear
      2. Annular
      3. Nummular
         1. circular
      4. Target
      5. Serpiginous
         1. fungal/parasitic
      6. Reticulated
         1. lacy pattern
4. Texture
   1. Verrucous
      1. irreg. surface
   2. Linchenification
      1. epidermal thickening w. accentutaion of skin lines
      2. Etio
         1. chronic irritation
   3. Induration
      1. dermal thickening
         1. feels
            1. hard and rough
   4. Umbilicated
      1. with a central indentation
5. Location
   1. Single or multiple lesions?
   2. presence on certain body parts
      1. mb significant
   3. Random vs. patterned
   4. Symmetric vs asymmetric
   5. Sun-exposed vs not
6. Color
   1. Red
      1. erythema
      2. INC blood flow to skin
   2. Orange
      1. hypercarotenemia
   3. Yellow
      1. Jaundice
      2. Heavy metal poisoning
      3. Myxedema
      4. Uremia
   4. Green
      1. pseudomonas
         1. in fingernails
   5. Violet
      1. darkening cutaneous hemorrhage
      2. vasculitis
   6. Gray/blue skin
      1. cyanosis
      2. metal deposits
   7. Black
      1. melanocytic lesions
      2. infection
      3. arterial insufficiency
      4. Trench mouth
7. Other Clinical Signs
   1. Dermatographism
      1. urticaria after stroking the skin
   2. Diascopy
      1. pressure to indicate blanching
      2. hemorrhagic lesions
         1. don't blanch
      3. Inflammatory
         1. blanch
   3. Darier's Sign
      1. – stroking lesions causes intense and sudden erythema and wheal formation
   4. Nikolsky's Sign
      1. bullae formation and erosion following gentle traction pressure
      2. Pemphigus
   5. Auspitz' Sign
      1. pinpoint bleeding after removal of plaques
   6. Koebner’s Phenomenon
      1. areas of trauma
         1. makes a line
      2. Lichen Planus
8. Diagnostic Tests
   1. Biopsy
      1. suspected malignancies
      2. unknown lesion that persist
   2. Patch test for allergies
   3. Bacteria
      1. Cultures
      2. Gram stain
   4. Viral
      1. Tzanck smear
         1. distinguish btw
   5. Fungal
      1. Cultures
      2. KOH test
      3. Skin scraping
      4. Wood's lamp
         1. UV light
   6. Immunofluorescence
9. Atopic triad
   1. asthma
   2. allergy
   3. allergic dermatitis