Comedo

What is a comedo?

A comedo (plural comedones) is a plugged follicular orifice.

• Open comedones (blackheads) are grey, orange, brown or black papules. The keratinous contents can be expressed or extracted.
• Closed comedones (whiteheads) are uninflamed skin-coloured papules. They must be punctured to remove their contents.

Open comedones 

Closed comedones 

Which conditions are characterised by a comedo?

Skin lesions and conditions in which there are prominent comedones include:

• Acne, especially acne vulgaris and comedonal acne
• Hidradenitis suppurativa
• Solar (senile) comedones and Favre Racouchot syndrome
• Discoid lupus erythematosus
• A seborrhoeic keratosis (best seen on dermatoscopy)
• A compound or dermal papillomatous melanocytic naevus or mole (best seen on dermatoscopy)
• A comedone naevus
• An epidermal cyst (giant comedo)
• A dilated pore of Winer
• Enlarged pores.

Comedonal acne 

Comedones in hidradenitis suppurativa 

Solar comedones 

Discoid lupus erythematosus 

Dermatoscopy of seborrhoeic keratosis. Rectangles highlight comedones 

Papillomatous naevus 

Comedone naevus 

Giant comedo 

Multiheaded comedo cyst