What are primary skin lesions?
They develope from originally normal skin and are directly associated with a disease process.
Which are the primary lesions?
What are macules? Patches?
Circumbscribed skin with altered color, without any elevation or depression.
A macular rash is called macular exanthema.
A patch is a macule > 1cm in diameter.
Examples of macules:
Vitiligo (white macules)
“Café au lait spots” (brown macules)
Mongolian spots (blue macules)
Port wine staines (red macules)
What is a papule?
Superficial, solid, raised lesions usually < 1cm in diameter with well or ill-defined borders. It is infiltrative.
A papular rash is called papular exanthema.
- Solitary papules:
- Dermal nevus, basal cell carcinoma, nodular melanoma
- Multiple papules:
- Condyloma acuminata, lichen planus, syringomas, psoriasis, secondary syphilis, neurofibromatosis, …
What is a plaque?
Flat-topped, plateau-like solid elevation (papule) > 1cm with infiltration.
- Solitary plaques:
- Lichen simplex chronicus, Bowen’s disease, superficial spreading melanoma, …
- Multiple plaques:
- Psoriasis, mycosis fungoides
- Atopic dermatitis, eczematous dermatitis, psoriasis, mycosis fungoides, …
What is a nodule?
It is solid, round or oval, non-flat-topped elevation (papule) which is > 2cm in diameter. Arises from the dermis or subcutis.
- Solitary nodules:
- Dermal nevus, basal cell carcinoma, nodular melanoma, …
- Mutliple nodules:
- Lipoma, metastatic melanoma, metastatic cancer
What is a wheal?
Erythematous plaque of dermal origin. Edema under the surface. Characteristic of uritcaria.
Disappears within 24-48h.
A rash consisting of wheals is called urticarial exanthema or urticaria.
What is a vesicle? Bulla?
Circumbscribed epidermal or dermal clear fluid-filled raised lesion (blister) < 0.5cm in diameter. If > 0.5cm it is a bulla.
Examples of vesicular/bullous lesions:
Varicella bullous pemphigoid
What is a pustule?
It is a raised vesicle filled with pus, which may be white, yellow, green or hemorrhagic.
Herpes simplex and zoster
What is a cyst?
Cavity (closed sac) in the skin containing air, serous, pustular or haemorrhagic fluid, or semi-solid material (such as sebum). It’s covered by an epithelial wall.
Cystic basal cell carcinoma