On the lookout for acne, psoriasis and eczema

Skin problems are an important component of primary-care practice. It is essential for the family doctor to be comfortable in assessing and managing common cutaneous conditions. This primer reviews three common skin conditions seen in primary care: acne, psoriasis and eczema.

Acne
Acne is an inflammatory disorder of pilosebaceous units, prevalent in adolescence. The characteristic lesions are open (black) and closed (white) comedones, inflammatory papules, pustules, nodules, cysts and potentially scarring. The skin with sebaceous glands is affected, that is, mostly the face and upper trunk. The etiology of acne is multifactorial and includes abnormal follicular keratinization, increased sebum production secondary to androgens, Propionibacterium acnes bacteria proliferation and inflammation. In women with acne and associated irregular periods and/or hirsutism, workup for an underlying hormonal problem, such as polycystic ovarian syndrome, is warranted. Common differential diagnosis of acne includes folliculitis, perioral dermatitis, seborrheic dermatitis and rosacea.

Treatment options depend on acne type and severity. Topical therapies include topical retinoids, benzoyl peroxide (2% to 10%), topical antibiotics (for example, clindamycin and erythromycin), over-the-counter preparations of salicylic acid and combination products. Of note, retinoids specifically target comedonal lesions, whereas antimicrobial and/or benzoyl peroxide products are mostly used for inflammatory lesions. Systemic acne therapies include oral antibiotics such as tetracycline, doxycycline and minocycline; hormonal therapies, including oral contraceptives and spironolactone; and isotretinoin. Some indications for oral isotretinoin are: moderate or severe acne, typically with scarring, and inadequate improvement with systemic antibiotics or hormonal therapy. Physical therapeutic modalities for acne include comedone extraction, chemical peels and microdermabrasion, intralesional corticosteroid injections for acne cysts, Blu-U light photodynamic therapy, as well as injectable fillers and laser resurfacing for acne scarring.

Psoriasis

Psoriasis: Characteristic erythematous plaques with silvery-white scale are typically distributed over extensor surfaces, including knees.

Psoriasis is a chronic scaly dermatosis that affects 1% to 3% of the population. The etiology of psoriasis is multifactorial and includes a genetic component, human lymphocyte antigen associations and cytokine inflammatory cascade. Characteristic erythematous plaques with silvery-white scale are typically distributed over extensor surfaces (elbows, knees), scalp, sacrum and other sites. Types of psoriasis include plaque psoriasis, guttate psoriasis (typically seen after streptococcal pharyngitis), erythrodermic psoriasis and pustular psoriasis. Up to 25% of patients with psoriasis also have associated psoriatic arthritis, most commonly of the small joints of the hands and feet. Topical treatments for psoriasis include moisturizers, topical steroids, a combination of a topical steroid with the vitamin D derivative calcipotriol (e.g., Dovobet ointment), tar (e.g., LCD) and salicylic acid preparations, topical immunomodulators and intralesional steroids. Phototherapy is an effective modality, especially for widespread psoriasis. Systemic treatment options for psoriasis are divided into traditional therapies, such as methotrexate, acitretin and cyclosporine, as well as newer biologic therapies such as etanercept (Enbrel), infliximab (Remicade), efalizumab (Raptiva), alefacept (Amevive) and adalimumab (Humira).

Eczema
Eczema or dermatitis is a broad term representing a group of conditions associated with skin hypersensitivity and typically characterized by pruritic erythematous patches. The types of eczema include:

• Atopic eczema: e.g., typically infantile and childhood eczema.

Psoriasis: Characteristic erythematous plaques with silvery-white scale are typically distributed over extensor surfaces, including knees.

• Asteatotic eczema: e.g., elderly with dry skin.

• Dyshidrotic eczema (pompholyx): eczema of hands and feet, usually starting off as small vesicles.

• Allergic contact dermatitis: T-cell mediated skin allergy. Specialized patch-testing is often required to confirm the diagnosis. Of note, poison ivy reaction is a form of allergic contact dermatitis.

• Irritant contact dermatitis: skin dermatitis triggered by an irritant such as water.

• Nummular dermatitis: coin-shaped eczematous patches. It is important to differentiate nummular eczema from tinea corporis and psoriasis.

• Stasis dermatitis: typically lower leg dermatitis associated with venous insufficiency.

• Neurodermatitis and lichen simplex: habit-itch eczema, e.g., scratcher’s and lip-licker’s dermatitis.

• Pityriasis alba: common type of eczema seen in young children, in which low-grade inflammation leads to hypopigmented patches, predominantly on the face.

Atopic dermatitis is a prototype of eczema commonly seen in primary care and pediatric practice. The condition usually starts in early infancy and is typified by pruritus (often referred to as “the itch that rashes”), eczematous lesions, xerosis (dry skin), and lichenification (thickening) of the skin. Atopic dermatitis is often associated with other atopic diseases, including asthma, hay fever and allergic rhinitis. While 80% of children develop atopic dermatitis before the age of one year, the majority will outgrow it by ages 10 to 12 years. Basic skin care routine is paramount in management of atopic dermatitis. It includes increasing humidity at home (especially in winter time), bathing in emulsifying oils, and applying moisturizer after bathing and at least a few times daily. Antihistamines can be used for pruritus control, while antibiotic therapy should be considered for areas of secondary infection, i.e., impetiginization.

Topical treatments of atopic dermatitis include topical steroids and topical immunomodulators, such as pimecrolimus (Elidel) and tacrolimus (Protopic). In topical therapy, creams are mostly used for acute inflammatory eczema, whereas ointments are more occlusive and are preferred for chronic, dry and lichenified eczema. Topical steroids are often used to control initial eczema flares, while topical immunomodulators can be subsequently used for prophylaxis, maintenance and as a nice option in “steroid-phobic” patients. Other options for severe eczema include UVB phototherapy and systemic immunosuppressive agents, such as short courses of prednisone for eczema flares.