Dermatology

  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

  4. Color

  5. Secondary Morphology

  6. Distribution

 

Primary Morphology

Macule

Example: Petechiae

Example of Petechiae (Petechia) showing small red spots on legs

Patch

Example: Vitiligo

Example of vitiligo showing loss of skin pigmentation in blotches under arm

Plaque

Example: Psoriasis

Example of Psoriasis showing red flaking skin on leg

Papule

Examples: Angioma, Wart

Example of cherry angioma showing small round red growth on skin

Example of skin wart on finger

Nodule

Example: Epidermal Inclusion Cyst

Example of Epidermal inclusion cyst (sebaceous cyst / epidermoid cyst)

Vesicle

Example: Herpes

Example of herpes skin rash

Pustule

Example: Acne

Example of acne skin rash

Bullae

Example: Bullous pemphigoid

Example of bullous pemphigoid large fluid-filled blisters on legs

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Size

How Small?

Example: Superficial Spreading Melanoma

small melanoma

How Large?

Example: Acral Lentiginous Melanoma

acral lentiginous melanoma

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Demarcation

Clearly Defined?

Example: Erysipelas

erysipelas

Not Well Define

Color

White

Example: Vitiligo

white patch of vitiligo

Red

Example: Drug Eruption

drug eruption rash

Purple

Example: Kaposi Sarcoma

Kaposi Sarcoma

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Brown

Example: Sarcoidosis

Sarcoidosis

Yellow

Example: Xanthelasma

Xanthelasma

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Black

Example: Black Eschar

Black Eschar

Blue

Example: Blue Nevus

Blue Nevus

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Secondary Morphology

Serum (Dried Crust)

Example: Impetigo

Impetigo

Fissure

Example: Psoriasis

Psoriasis fissuring of hand

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Lichenification

Thickening of skin. Note the accentuation of skin lines

Example: Chronic Rubbing, Lichen simplex chronicus

lichen simplex chronicus

Erosion

Partial loss of epidermis.

Example: Scratching, minor skin injury

erosion of heel of foot

Ulceration

Full thickness loss of epidermis. 

Example: Pyoderma gangrenosum, Pressure/Decubitus ulcer

Impetigo

Scaling

Example: Psoriasis (picture), Ichthyosis

scale from psoriasis

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Distribution

Extensor surfaces

Example: Psoriasis

psoriasis of extensor surfaces

Generalized

Example: Viral, Drug reaction

Drug eruption showing generalized rash

Photodistributive

Example: Lupus / Dermatomyositis

photodistribution rash

 

 

 

Applying What We Learned

GenDermExam

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