General Dermatology

ACNE AND RELATED CONDITIONS
ACNE VULGARIS AND SPECIAL FORMS (Tables 3-1, 3-2)
Acne Vulgaris
  • Inflammation of the pilosebaceous unit (PSU) causing comedones, papulopustules and nodules
  • Four key pathogenic factors
    • Abnormal follicular keratinization
      • ↑ Corneocyte cohesiveness and proliferation
    • Propionibacterium acnes (P. acnes) in sebum
      • Gram + anaerobic rod, resident flora in follicle but acne patients with higher concentration
      • Naturally produces porphyrins (coproporphyrin III), which is the target of light-based acne therapy
      • Secretes lipases which cleave lipids in sebum into pro-inflammatory free fatty acids (FFAs), which are both comedogenic and chemotactic
      • Binds/activate toll-like receptor 2 (TLR2)
    • Inflammation
      • ↑ IL-1, IL-8, and TNF-α through TLR-2 pathway
    • Hormonal effect on sebum due to androgens
      • ↑ Sebum production due to androgen-stimulated sebaceous glands
      • Androgen receptors present on basal layer of sebaceous gland and ORS of hair follicle; respond to most potent androgen, dihydrotestosterone (DHT), and testosterone (latter produced by gonads and can be converted to DHT via 5α -reductase)
      • Dehydroepiandrosterone sulfate (DHEA-S): weak androgen produced by adrenal glands
  • Microscopic precursor lesion: microcomedo
  • May present with non-inflammatory comedones (open/closed), inflammatory papules, pustules, ± nodules
  • Histology: follicular distension often with ruptured PSU and accompanying brisk inflammatory response, ± foreign body reaction with multinucleated giant cells
  • Treatment:
   
 
 
Topical therapy
Benzoyl peroxide, retinoids (tretinoin, adapalene, tazarotene), azelaic acid, dapsone, clindamycin, sodium sulfacetamide/sulfur and salicyclic acid

   
Topical retinoids: comedolytic and downregulate TLR-2
   
   
 
Other therapies
Oral antibiotic, isotretinoin, oral contraceptive pill; photodynamic therapy or blue light alone

   
Cannot combine isotretinoin and tetracycline due to risk of pseudotumor cerebri
   
   
 
   
Figure 3.1 A: Acne conglobata B: Acne excoriée C: Acne in PCOS
Figure 3.1
A: Acne conglobata
B: Acne excoriée
C: Acne in PCOS


   
 
Table 3-1 Acne Variants
TypeClinical Features
 
Acne fulminans
– Severe form of nodulocystic acne in young males (13–16 years old)

– Presents with sudden-onset suppurative nodular acne with ulceration, eschars and systemic symptoms (may include myalgias, arthralgias, fever, ↑ ESR, ↑ WBCs, ± sterile osteolytic bone lesions typically over clavicle or sternum)

– Treat with low-dose accutane and prednisone or prednisone alone initially, followed by isotretinoin (to prevent flare and formation of granulation tissue)
 
Acne conglobata
(Figures 3.1A, 3.2A)
– Acute-onset nodulocystic acne without systemic manifestations

– Part of the follicular occlusion triad (dissecting cellulitis of scalp, pilonidal cyst and hidradenitis suppurativa)
 
Acne excoriée
(Figure 3.1B)
– Mainly seen in young women with emotional or psychological disorders (such as obsessivecompulsive disorder) who repeatedly pick at lesions

– Presents as mild acne with several excoriations, crusted erosions and sometimes ulcerations with subsequent scarring

Antidepressants may be warranted
 
Acne with underlying
endocrinologic abnormality
(Figure 3.1C)
– If acne with accompanying hirsutism ± irregular menses, check lab work for hormonal abnormality (check LH, FSH, DHEA-S, free and total testosterone)

– Source of androgens

    Ovarian androgens: testosterone
    Adrenal androgens: DHEA-S, 17-hydroxyprogesterone
Polycystic ovarian syndrome (PCOS):

– Seen in 5–10% of women of reproductive age

– Androgen excess causing hirsutism, irregular menses, ± polycystic ovaries, obesity, insulin resistance, ↑ LH/FSH ratio, ↓ fertility, ↑ testosterone

– Acne lesions typically nodular and involve lower ½ of face (especially jawline)

– Treatment: oral contraceptive pill (resulting in ↑ SHBG, ↓ free testosterone), spironolactone (off-label, blocks androgen receptor)

Late congenital adrenal hyperplasia:

– ↑ DHEA-S or 17-hydroxyprogesterone due to partial deficiency of adrenal enzymes (commonly 21-hydroxylase or 11-hydroxylase)
 
Industrial acne
– Due to exposure to insoluble cutting oils or chlorinated aromatic hydrocarbons (such as chlorinated dioxins and dibenzofurans)

– Chloracne (form of industrial acne): presents with comedones, pustules and cysts over malar cheeks, retroauricular region, and scrotum
 
Acne mechanica
– Due to repeated obstruction of the pilosebaceous unit through friction/pressure
 
Neonatal acne (Cephalic
neonatal pustulosis)
– Begins around 2 weeks of age and often resolves by third month of age

– Presents with erythematous small papules on cheeks
 
Infantile acne
– Typically begins around 3–6 months of age, resolves within 1–2 years
 
Drug-induced acne
(Acneiform eruption)
– Due to corticosteroid, phenytoin, lithium, isoniazid, iodides, epidermal growth factor receptor inhibitors (EGFRI: cetuximab, erlotinib, gefitinib), anabolic steroids

– Presents with abrupt-onset monomorphic-appearing papules and pustules; comedones typically not seen
    
 
   


   
 
Table 3-2 Syndromes Associated with Acne
 Syndrome Clinical Features
 
PAPA syndrome
 
Pyogenic Arthritis (sterile), Pyoderma gangrenosum, Acne

– Inherited (AD), CD2 binding protein 1 (CD2BP1) mutation; CD2BP1 is a pyrininteracting protein, which is part of inflammatory pathway associated with familial Mediterranean fever, Muckle-Wells syndrome, and familial cold urticaria

– Skin changes typically present near or at puberty
 
HAIR-AN
Hyper Androgenism, Insulin Resistance, Acanthosis Nigricans
 
SAPHO
(Chronic recurrent multifocalosteomyelitis)
 
Synovitis, Acne (conglobata), Pustulosis (palmoplantar), Hyperostosis, Osteitis

– Inflammatory bone changes (commonly involving sternoclavicular joint, spine {spondyloarthropathy} and long bones); peripheral arthritis also common

– 1 st line treatment: bisphosphonates suggested in many case reports and series; other treatments include mainstay therapies for psoriatic arthritis (methotrexate, anti-TNF a agents, etc.)