OCCURRENCE Very common, affecting approximately 85% of young people.
AGE OF ONSET Puberty; may appear for the first time around 25 years or older.
SEX More severe in males than in females.
RACE Lower incidence in Asians and Africans.
GENETIC ASPECTS Multifactorial genetic background and familial predisposition. Most individuals with cystic acne have a parent(s) with history of severe acne. Severe acne may be associated with XYY syndrome (rare).
Pathogenesis
Key factors are follicular keratinization, androgens, and Cutibacterium acnes.
Follicular plugging (comedone) prevents drainage of sebum; androgens (quantitatively and qualitatively normal in serum) stimulate sebaceous glands to produce more sebum. Bacterial (C. acnes) lipase converts lipids to fatty acids and produces proinflammatory mediators (IL-I, TNF-α), which lead to an inflammatory response. Distended follicle walls break; sebum, lipids, fatty acids, keratin, and bacteria enter the dermis, provoking an inflammatory and foreign-body response. Intense inflammation leads to scars.
CONTRIBUTORY FACTORS Acnegenic mineral oils, rarely dioxin, and others listed below.
DrugsLithium, hydantoin, isoniazid, glucocorticoids, oral contraceptives, iodides, bromides and androgens, and danazol.
OthersEmotional stress can cause exacerbations. Occlusion and pressure on the skin, such as leaning the face on the hands, is a very important and often unrecognized exacerbating factor (acne mechanica). Cow's milk may be associated with acne.
DURATION OF LESIONS Weeks to months.
SEASON Often worse in fall and winter.
SYMPTOMS Pain in lesions (especially the nodulocystic type).
SKIN LESIONSComedones—open (blackheads) or closed (whiteheads); comedonal acne (Fig. 1-1). Papules and papulopustules—that is, a papule topped by a pustule; papulopustular acne (Fig. 1-2). Nodules or cysts—1 to 4 cm in diameter; nodulocystic acne (Fig. 1-3). Soft nodules result from repeated follicular ruptures and re-encapsulations with inflammation, abscess formation (cysts), and foreign-body reaction (Fig. 1-4). Round, isolated single nodules and cysts coalesce to linear mounds and sinus tracts (Figs. 1-3 and 1-5). Sinuses: draining epithelial-lined tracts, usually with nodular acne. Scars: atrophic depressed (often pitted) or hypertrophic (at times, keloidal).
Sites of Predilection Face, neck, trunk, upper arms, and buttocks.
NEONATAL ACNE Occurs on the nose and cheeks in newborns or infants, and is related to glandular development; transient and self-healing.
ACNE EXCORIÉE Usually occurs in young women, and is associated with extensive excoriations and scarring resulting from emotional and psychological problems (obsessive compulsive disorder).
ACNE MECHANICA Flares of acne occur on cheeks, chin, and forehead, because of leaning the face on the hands or forehead, and from the pressure of sports gear such as helmets.
ACNE CONGLOBATA Severe cystic acne (Figs. 1-5 and 1-6) occurs with more involvement of the trunk than the face, but also occurs on the buttocks. Coalescing nodules, cysts, abscesses, and ulceration. Spontaneous remission rare. Rarely seen in XYY genotype or polycystic ovary syndrome (PCOS).
ACNE FULMINANS Occurs primarily in teenage boys. Acute onset, severe cystic acne with suppuration and ulceration; malaise, fatigue, fever, generalized arthralgias, leukocytosis, and elevated ESR.
TROPICAL ACNE With severe folliculitis, inflammatory nodules, draining cysts on the trunk and buttocks, particularly in tropical climates; secondary infection with Staphylococcus aureus.
OCCUPATIONAL ACNE Caused by exposure to tar derivatives, cutting oils, chlorinated hydrocarbons (see "Chloracne" as follows). Not restricted to predilection sites, and can appear on other (covered) body sites, such as arms, legs, or buttocks.
CHLORACNE Caused by exposure to chlorinated aromatic hydrocarbons in electrical conductors, insecticides, and herbicides. Sometimes very severe because of industrial accidents or intended poisoning (e.g., dioxin).
ACNE COSMETICA Caused by comedogenic cosmetics.
Pomade Acne On the forehead, usually in Africans from applying pomade to hair.
SAPHO SYNDROMESynovitis, acne fulminans, palmoplantar pustulosis, hidradenitis suppurativa, hyperkeratosis, and osteitis; very rare.
PAPA SYNDROME Sterile pyogenic arthritis, pyoderma gangrenosum acne. An inherited autoinflammatory disorder; very rare.
STEROID ACNE No comedones. Following systemic or topical glucocorticoids. Monomorphous folliculitis—small erythematous papules and pustules on chest and back.
DRUG-INDUCED ACNE No comedones. Monomorphous acne-like eruption caused by phenytoin, lithium, isoniazid, high-dose vitamin B complex, epidermal growth factor inhibitors (see Section 23, ACDR-related to chemotherapy), and halogenated compounds.
ACNE AESTIVALIS No comedones. Papular eruption after sun exposure. Usually on forehead, shoulders, arms, neck, and chest.
GRAM-NEGATIVE FOLLICULITIS Multiple tiny yellow pustules on top of acne vulgaris in long-term antibiotic administration.
Laboratory Examination
No laboratory examinations required. In the overwhelming majority of acne patients, hormone levels are normal. If an endocrine disorder is suspected, determine free testosterone, follicle-stimulating hormone, luteinizing hormone, and dehydroepiandrosterone sulfate (DHEAS) to exclude hyperandrogenism and PCOS. Recalcitrant acne can also be related to congenital adrenal hyperplasia (11β or 21β hydroxylase deficiency). If systemic isotretinoin treatment is planned, determine transaminase (ALT, AST), triglyceride, and cholesterol levels.
Note: Comedones are required for diagnosis of any type of acne. Comedones are not a feature of acne-like conditions (see preceding), and the following conditions: Face—S. aureus folliculitis, pseudofolliculitis barbae, rosacea, and perioral dermatitis. Trunk—Malassezia folliculitis, "hot-tub" pseudomonas folliculitis, S. aureus folliculitis, and acne-like conditions (see preceding).
Course
Often clears spontaneously by the early 20s, but can persist to the fourth decade or older. Flares occur in the winter and with the onset of menses. The sequela of acne is scarring that may be avoided by treatment, especially with oral isotretinoin early in the course of the disease (see below).
The goal of therapy is to remove any plugging of the pilar drainage, reduce sebum production, and treat bacterial colonization. The long-term goal is prevention of scarring.
Use topical antibiotics (clindamycin and erythromycin) and benzoyl peroxide gels (2%, 5%, or 10%). Topical retinoids (retinoic acid, adapalene, or tazarotene) require detailed instructions regarding gradual increases in concentration from 0.025% to 0.1% cream or gel. Best combined with benzoyl peroxide-mycin gels.
Note: Acne surgery (extractions of comedones) is helpful only when properly done and after pretreatment with topical retinoids.
MODERATE ACNE Add oral antibiotics to the above regimen. Minocycline is most effective, or doxycycline, starting at 100 mg twice daily and tapering to 50 mg daily as acne lessens. Use of oral isotretinoin in moderate acne to prevent scarring has become much more common and is very effective.
SEVERE ACNE In addition to topical treatment, systemic treatment with isotretinoin is indicated for cystic or conglobate acne, or any other acne refractory to treatment. This retinoid inhibits sebaceous gland function and keratinization, which is very effective. Oral isotretinoin leads to complete remission in almost all cases, lasting for months to years in the majority of patients.
Indications for Oral Isotretinoin Moderate, recalcitrant, and nodular acne.
Contraindications Isotretinoin is teratogenic and effective contraception is imperative. Concurrent tetracycline and isotretinoin may cause pseudotumor cerebri (benign intracranial swelling); therefore, the two medications should never be used together.
Warnings Determine blood lipids, transaminases (ALT, AST) before therapy. Around 25% of patients can develop increased plasma triglycerides. Patients may develop mild-to-moderate elevation of transaminase levels, which normalize with reduction of the drug dosage. Eyes: Night blindness has been reported, and patients may have decreased tolerance to contact lenses. Skin: An eczema-like rash caused by drug-induced dryness can occur and responds dramatically to low potency (class III) topical glucocorticoids. Dry lips and cheilitis almost always occur and must be treated. Reversible thinning of hair may occur very rarely, as may paronychia. Nose: Dryness of nasal mucosa and nosebleeds occur rarely. Other systems: Rarely depression, headaches, arthritis, and muscular pain, but pancreatitis can occur. For additional rare possible complications, consult the package insert.
Dosage Isotretinoin, 0.5 to 1 mg/kg daily given in divided doses with food to a total goal dose of 120 to 150 mg/kg.
OTHER SYSTEMIC TREATMENTS FOR SEVERE ACNE Adjunctive systemic glucocorticoids may be required in severe acne conglobata, acne fulminans, and SAPHO and PAPA syndromes. The TNF-α inhibitor infliximab and anakinra are investigational drugs in these severe forms and show promising effects. Note: For inflammatory cysts and nodules, intralesional triamcinolone is helpful (0.05 mL of a 3 to 5 mg/mL solution).