The Dermatology Exam: Learning the Language

Approach to General Exam

Approach to Multiple Rashes


 

Introduction

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

Macule

Example: Petechiae


Patch

Example: Vitiligo


Plaque

Example: Psoriasis


Papule

Examples: Angioma, Wart


Nodule

Example: Epidermal Inclusion Cyst


Vesicle

Example: Herpes


Pustule

Example: Acne


Bullae

Example: Bullous pemphigoid

Size

How Small?

Example: Superficial Spreading Melanoma

How Large?

Example: Acral Lentiginous Melanoma

Demarcation

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.

Color

White

Example: Vitiligo


Red

Example: Drug Eruption


Purple

Example: Kaposi Sarcoma


Brown

Example: Sarcoidosis


Yellow

Example: Xanthelasma


Black

Example: Black Eschar


Blue

Example: Blue Nevus

Secondary Morphology

Serum (Dried Crust)

Example: Impetigo


Fissure

Example: Psoriasis


Lichenification

Thickening of skin. Note the accentuation of skin lines

Example: Chronic Rubbing, Lichen simplex chronicus


Erosion

Partial loss of epidermis.

Example: Scratching, minor skin injury


Ulceration

Full thickness loss of epidermis. 

Example: Pyoderma gangrenosum, Pressure/Decubitus ulcer


Scaling

Example: Psoriasis (picture), Ichthyosis

Distribution

Extensor surfaces

Example: Psoriasis


Generalized

Example: Viral, Drug reaction


Photodistributive

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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