Giant comedone

A giant comedone is an exceptionally large blackhead.

This chapter is set out as follows:

• The abnormalities that arise could be due to either an increased production of the corneocytes lining the duct and, or an associated decrease in the rate at which the ductal corneocytes separate - but there is no data to confirm either of these suggestion

• Usually single but occasionally several can be found
• People who have very bad acne and atrophic scars are much more prone to developing giant comedo, however they frequently occur in the absence of previous acne
• Age - occur more in the middle-aged and elderly age groups

Distribution

• ​Can arise on most parts of the body but especially on areas which are rich in sebaceous glands such as the face, back and chest
• They are occasionally found where there are apocrine glands, as in the axillae, groins, perianal areas and scrotum

Morphology

• Size - lesions are between several mm and 2 cm in diameter
• The diagnosis is usually obvious with the comedone clearly visible underneath normal stretched skin 

• The diagnosis is usually straightforward as it is normally very easy to squeeze out the contents of the much distended duct. This is best done by placing a little piece of gauze either side of the comedone and pressing gently

• The problem is that in most instances the follicular ducts refill over a period of two to three months. Cautery of the residual duct, having evacuated the contents does not seem a very successful procedure. If the comedone is problematic it may be worth a trial of topical retinoids but no study has ever looked at this treatment