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Integumentary system ORGAN SYSTEMS

Seborrhoea

Chronic skin condition characterized by abnormal cornification or keratinization that causes excessive greasiness and scaling of the skin and haircoat.


Aetiology

  • Male sex
  • Premenopausal women during ovulation
  • Spring/summer seasons
  • Humid climate
  • African American race
  • Conditions with elevated androgens (i.e., congenital adrenal hyperplasia, androgen-secreting tumours of the ovaries or adrenal glands)

Clinical features

Common complaint is dry, greasy skin or patchy dermatitis that is initially nonpruritic but can become pruritic later on if the seborrhea worsens or lesions are infected with Staphylococcus or Malassezia spp. Most of the lesions are present on the neck and trunk area.

Presentations:

  • Seborrhea sicca (dry)
  • Seborrhea oleosa (greasy/oily skin)
  • Seborrheic dermatitis (patchy dermatitis)

Management

TOPICAL MANAGEMENT:

  • Retinoids
  • Cosmeceuticals

Retinoids (Vitamin A/retinol):

  • Natural derivativesRetinaldehyde, retinoic acid, and retinyl esters
  • Synthetic derivativesAdapalene & tazarotene

Cosmeceuticals:

Numerous cosmeceutical products and ingredients make claims that their use will reduce oily skin, but this discussion will be limited to evidence-based ingredients.

  • Topical 2% niacinamide (↓ sebum production)
  • Green tea (emulsions, etc) (↓ sebum production)
  • Topical 2% L-carnitine (augment β-oxidation, the catabolic process by which fatty acids are broken down & ↓ intracellular fatty acid content in human sebocytes)
  • sebosuppressive properties are warranted, it is a reasonable ingredient to recommend to patients concerned about oily skin

SYSTEMIC MANAGEMENT:

  • Isotretinoin or 13-cis retinoic acid
  • Spironolactone
  • Oral contraceptives

Isotretinoin or 13-cis retinoic acid (M/effective):

  • ↓ Size and secretion of sebaceous glands (sebum production decreases by 90% during oral isotretinoin therapy)
    • Lower dose (<0.5mg/kg/day): Oily skin alone without nodulocystic acne, but associated with a higher relapse rate
  • Overall, up to 17% patients require a 2nd course despite achieving the recommended cumulative dose of 120-150mg/kg
  • Adverse effects:
    • Dry skin, chapped lips, xerophthalmia, and secondary skin infections
    • Teratogenic drug (to help prevent this severe adverse risk, sexually active women must use 2 forms of contraception, and pregnancy testing is required for all female patients of childbearing potential at baseline and monthly until completion of therapy)

Spironolactone:

Used in the treatment of oily skin, acne, hirsutism, and androgenic alopecia in women in addition to use as an antihypertensive

  • Antihypertensive (potassium-sparing diuretic)
  • Aldosterone antagonist (androgen receptor blocker)
  • Inhibitor of 5a-reductase (human sebocytes contain Type 1 5a-reductase, which converts testosterone to the potent androgen 5a-dihydrotestosterone (DHT))
    • Thus, by inhibiting production of DHT and blocking testosterone & DHT from binding to sebocytes, spironolactone has been proven to inhibit sebocyte proliferation in a dose-dependent manner
    • Androgens stimulate sebocyte proliferation and contribute to seborrhea
  • Adverse effects: Menstrual irregularity (M/C), hyperkalemia

Oral contraceptives:

  • ↓ Ovarian & adrenal androgens and ↑ sex hormone-binding globulin (limits free testosterone)
  • Estrogens (inhibitory effect on excessive sebaceous gland activity in vivo)
  • Used in combination with a progestin (to avoid the risk of endometrial hyperplasia, or even cancer, that can result from unopposed estrogen)
    • eg. Ethinyl estradiol/drospirenone combination or ethinyl estradiol/cyproterone acetate combination
  • Adverse effect: ↑ risk of venous thromboembolism, nausea, breast tenderness, and breakthrough menstrual bleeding

OTHER MANAGEMENT:

  • Botulinum toxin
    • Cleaves proteins involved in vesicle fusion with the plasma membrane of the presynaptic neuron’s axon terminal. These vesicles contain acetylcholine, and botulinum toxin blocks the release of this neurotransmitter into the synaptic cleft where it would normally bind to a muscarinic receptor on a post-synaptic cell. In sebaceous glands, both immature and mature sebocytes express muscarinic acetylcholine receptors that are important for sebocyte differentiation and sebum production.
  • Photodynamic therapy (PDT)
    • Following the application of δ-aminolevulinic acid (ALA) (also treats acne vulgaris)
    • ALA preferentially absorbed by pilosebaceous units, and sebocytes metabolize ALA to light-sensitive protoporphyrin IX (PplX).When exposed to light at a suitable dose and wavelength, PplX forms cytotoxic free radicals that result in cell destruction and apoptosis of sebocytes.
  • Lasers: 1,450nm diode laser treatment (M/C)

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