The General Dermatology Exam: Learning the Language

The diagnosis of any skin lesion starts with an accurate description of it. To do that, you need to know how to describe a lesion with the associated language. This language, reviewed here, can be used to describe any skin finding.

Approach to General Exam

Approach to Multiple Rashes

Introduction to the Dermatology Exam

Before you can make a diagnosis of any skin lesion, it's important to be able to accurately describe the skin lesion. The purpose of this page is to cover the fundamental knowledge you will need to do this. 

Learn the Language of the Dermatology Exam

  1. Primary Morphology
    1. Macule - flat lesion less than 1 cm, without elevation or depression
    2. Patch - flat lesion greater than 1 cm, without elevation or depression
    3. Plaque - flat, elevated lesion, usually greater than 1 cm
    4. Papule - elevated, solid lesion less than 1 cm
    5. Nodule - elevated, solid lesion greater than 1 cm
    6. Vesicle - elevated, fluid-filled lesion, usually less than 1 cm 
    7. Pustule - elevated, pus-filled lesion, usually less than 1 cm
    8. Bulla - elevated, fluid-filled lesion, usually greater than 1 cm 
  2. Size
  3. Demarcation
    1. Well-demarcated
    2. Not well-demarcated
  4. Color
    1. White
    2. Red
    3. Purple
    4. Brown
    5. Yellow
    6. Black
    7. Blue
  5. Secondary Morphology
    1. Serum (Dry crust)
    2. Fissure
    3. Lichenification
    4. Erosion
    5. Ulceration
    6. Scaling
  6. Distribution
    1. Extensor
    2. Generalized
    3. Photodistributive 


Primary Morphology


Example: Petechiae


Example: Vitiligo


Example: Psoriasis


Examples: Angioma, Wart


Example: Epidermal Inclusion Cyst


Example: Herpes


Example: Acne


Example: Bullous pemphigoid


How Small?

Example: Superficial Spreading Melanoma

How Large?

Example: Acral Lentiginous Melanoma


Clearly Defined?

Example: Erysipelas

Not Well Defined?

Example: Cellulitis

Consult the Expert

Justin Ko

Dr. Justin Ko is a Clinical Assistant Professor, Dermatologist and Clinic Chief and Director of Medical Dermatology at Stanford.

Clinical Pearl

A good dermatology exam requires a well lit room and sometimes a hand held light. Sometimes, you may need a ruler and magnifiying glass. Remember that sometimes the palpation of skin lesions can be just as important as what you see.



Example: Vitiligo


Example: Drug Eruption


Example: Kaposi Sarcoma


Example: Sarcoidosis


Example: Xanthelasma


Example: Black Eschar


Example: Blue Nevus

Secondary Morphology

Serum (Dried Crust)

Example: Impetigo


Example: Psoriasis


Thickening of skin. Note the accentuation of skin lines

Example: Chronic Rubbing, Lichen simplex chronicus


Partial loss of epidermis.

Example: Scratching, minor skin injury


Full thickness loss of epidermis. 

Example: Pyoderma gangrenosum, Pressure/Decubitus ulcer


Example: Psoriasis (picture), Ichthyosis


Extensor surfaces

Example: Psoriasis


Example: Viral, Drug reaction


Example: Lupus / Dermatomyositis




Applying What We Learned

Based on the above image, here's how we'd describe this skin lesion:

  1. Primary morphology -> plaque, 
  2. Size -> a few centimeters 
  3. Well-Demarcated
  4. Color -> Dully red
  5. Secondary morphology -> Dry serum/crusting, erosions and scaling
  6. Distribution -> Extensor surface of leg

Diagnosis is consistent with psoriasis given the above description.



















Key Learning Points

  • Learn the language of the skin exam
  • Learn to apply this approach for any skin exam

Related to Dermatology Exam

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