Primary skin lesions

Primary Lesions Summary

• 1. Macule: Flat circumscribed area of change in skin color
• 2. Papule: small circumscribed elevation of the skin
• 3. Nodule: Solid, circumscribed elevation of the skin whose greater part is beneath skin surface (felt more than seen)
• 4. Plaque: flat topped palpable lesion (gathering of papules)
• 5. Vesicle: collection of clear fluid (<5mm in diameter)
• 6. Bulla: like vesicle, but > 5 mm
• 7. Wheal: Transient, slightly raised lesion with pale center and pink margin. Seen in urticaria.
• 8. Purpura: Visible collection of blood under the skin e.g. Vasculitis
• 9. Telangectasia: Dilated capillaries visible on skin surface
• 10. Burrow: Tunnel in the skin (e.g. Scabies)

Morphology

• The word morphology is used by dermatologists to describe the form and structure of skin lesions
• The morphologic characteristics of skin lesions are key elements in establishing the diagnosis and communicating skin findings
• There are two steps in establishing the morphology of any given skin condition:
  1. Careful visual and tactile inspection
  2. Application of correct descriptors

Visual and Tactile Inspection

• Accumulate detailed information about the visual and tactile aspects of the skin findings
• Be able to communicate an accurate description so someone on the other end of a phone can get a mental picture of what you see.
• Question 1
  • How would you fill in the description of the item depicted on the next slide?

Question 1

• How would you describe the object to the right?
• Be as detailed as you can be!

• This is a red, circular, shiny object with a small invagination on top. It measures 8 cm. It is in a white background and casts a shadow.
• The above description identifies:
  1. Palpability (indicated by shadow)
  2. Color
  3. Shape
  4. Texture
  5. Size
  6. Location

Application of the correct descriptors

• We have just reviewed careful visual inspection
• We will now define the terms dermatologists use to describe skin lesions
• We will then have a series of cases for you to practice describing so you can use the correct descriptors.

Primary skin lesions

Macule

• (L. macula, “spot”)
• A macule is flat; if you can feel it, then it is not a macule.

Patch

• Patches are flat but larger than macules
• If it’s flat and larger than 1 cm, it is a patch

Papule

• (L. papula, “pimple”)

• A papule is a circumscribed palpable elevation of the skin less than 1 cm in diameter
• Dermal (drug eruption, lipid deposits), epidermal (warts, molluscum), or both (lichen planus)

Plaque

• Plaques > 1 cm - A slightly raised lesion greater than 1 cm in diameter - They cast a shadow with side lighting
• Papules confluence (psoriasis)
• Patch thickening (mycosis fungoides the lymphoma of the skin)

• It is caused by a proliferation of cells in epidermis or superficial dermis

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Nodule

Palpable solid deep lesion (depth > diameter)

• Epidermal
• Dermal

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Vesicle

• A raised lesion less than 0.5 cm in diameter containing clear fluid

Vesicles - Bulla

Bulla

• A vesicle that is greater than 0.5 cm in diameter is known as a bulla.

Pustule

Pus is made up of leukocytes and a thin fluid called liquor puris (L.“pus liquid”)

• A pustule is a raised lesion less than 0.5 cm in diameter containing yellow fluid, which may be sterile as in acne and pustular psoriasis, or infected.

Sterile pastules; ABCD - seen in acne, psoarsos, bacterial staph, commidone?

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Wheal

• A wheal is a transient, itchy, pink or red swelling of the skin, often with central pallor.

Cyst

palpable soft sac containing fluid.

• Epidermal
• Dermal

Telangiectasia

• Dilatation of capillaries gives rise to this skin condition.

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