Sebaceous gland
Hypodermis & appendages · Holocrine Androgen-driven Acne
Holocrine gland of the pilosebaceous unit whose cells disintegrate entirely to release sebum into the follicular infundibulum. Its size and output are androgen-dependent, which is why acne begins at adrenarche.
Traced from the start
Detail
- Secretion mode
- Holocrine — the whole cell breaks down and becomes the secretion, unlike merocrine (eccrine sweat) or apocrine glands
- Sebum
- Triglycerides, wax esters and squalene; lubricates hair and skin and supplies substrate for the skin surface microbiome
- Control
- Androgens (including adrenal DHEAS at adrenarche) enlarge the gland and raise output; isotretinoin shrinks it
- Distribution
- Densest on face, scalp, chest and upper back; absent from palms and soles
When it goes wrong
Follicular hyperkeratinisation, androgen-driven sebum excess, Cutibacterium acnes colonisation and inflammation
Acne vulgaris; treatment escalates from topical retinoid and benzoyl peroxide through oral doxycycline to isotretinoin, which is teratogenic and requires strict pregnancy prevention and lipid and liver monitoring
Hyperandrogenism from polycystic ovary syndrome, congenital adrenal hyperplasia or an androgen-secreting tumour
Acne with hirsutism, oligomenorrhoea and androgenetic alopecia — a pattern that should prompt endocrine investigation rather than dermatological treatment alone
Sebaceous carcinoma or multiple sebaceous neoplasms
Muir-Torre syndrome, a Lynch syndrome variant with mismatch repair deficiency: screen for colorectal and genitourinary malignancy
Practise this structure
16 questions in the bank tagged Skin.
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