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Emergency and Acute Medicine - Seborrheic Dermatitis
Seborrheic dermatitis is a common, chronic papulosquamous inflammatory skin disorder that affects individuals of all ages. It ranges in severity from mild dandruff to extensive, greasy, scaling plaques that are typically yellow to red or brown in color. The condition most often involves areas rich in sebaceous glands, such as the scalp, face, chest, and skin folds. It follows a relapsing and remitting course, with exacerbations frequently triggered by physical stress, emotional stress, or intercurrent illness.
The exact cause of seborrheic dermatitis is not fully understood, but it is considered multifactorial. Environmental, genetic, hormonal, immunologic, and microbial influences all play a role. A strong association exists with the yeast Malassezia, which thrives in sebaceous areas and contributes to inflammation. The disease involves a complex interaction of immune responses, inflammation, and increased epidermal turnover. Certain conditions predispose individuals to more severe or refractory disease, including neurologic disorders such as Parkinson disease, immunosuppression such as HIV/AIDS, mood disorders, and chronic systemic illness. Various medications, including lithium and interferon, may also exacerbate the condition.
Clinical presentation varies by age group. In infants, seborrheic dermatitis commonly appears within the first few weeks of life and is usually self-limited, resolving by 12 months. The classic manifestation is cradle cap, characterized by thick, greasy scales on the scalp, sometimes accompanied by inflammation or secondary infection. It may also involve flexural areas, presenting similarly to diaper dermatitis. In children, seborrheic dermatitis may present as blepharitis with scaling along the eyelid margins and can be persistent or resistant to treatment.
In adolescents and adults, seborrheic dermatitis typically presents with mild itching and greasy, fine scaling over erythematous skin. The distribution is usually bilateral and symmetrical, affecting the scalp, eyebrows, eyelids, nasolabial folds, ears, posterior neck, and presternal area, as well as body folds such as the axillae and groin. In individuals with darker skin tones, affected areas may show hypopigmentation. The condition is often exacerbated by infrequent washing and environmental stressors.
Diagnosis is primarily clinical, based on history and physical examination. Laboratory testing is rarely required but may include potassium hydroxide preparation to assess for yeast or fungal cultures to exclude dermatophyte infections. Skin biopsy is seldom necessary and is reserved for unclear or treatment-resistant cases.
Management focuses on controlling symptoms rather than curing the disease, as seborrheic dermatitis is chronic. General measures include patient education, regular cleansing, and the use of emollients such as mineral oil to soften scales before removal. Gentle brushing after washing can help remove adherent scales. Moderate exposure to sunlight may also be beneficial due to its inhibitory effect on yeast growth.
Pharmacologic treatment is typically multifaceted. First-line therapy includes topical antifungal agents such as ketoconazole, which target Malassezia species, along with low-potency topical corticosteroids like hydrocortisone for short-term control of inflammation. Medicated shampoos containing pyrithione zinc, selenium sulfide, coal tar, or salicylic acid are commonly used, especially for scalp involvement. In more resistant cases, second-line treatments include ciclopirox and topical calcineurin inhibitors such as tacrolimus or pimecrolimus, which provide anti-inflammatory effects without the long-term risks of corticosteroids.
In infants, treatment is generally gentle and supportive, using emollients, mild shampoos, and low-potency topical steroids if needed. Blepharitis associated with seborrheic dermatitis is managed with warm compresses and careful cleansing of the eyelid margins. Severe cases, particularly those involving extensive scaling or secondary infection, may require more intensive therapy.
The prognosis is generally good, although seborrheic dermatitis tends to be chronic with recurrent flares. Symptoms often improve within 7 to 10 days of treatment, but complete resolution may take longer, and recurrence is common. Patients should be advised about the chronic nature of the condition and the importance of maintenance therapy.
Important clinical considerations include recognizing that sudden or severe seborrheic dermatitis may be a sign of underlying immunosuppression, particularly HIV infection. Overuse of topical corticosteroids should be avoided due to the risk of skin atrophy and rebound flares. Clinicians should also remain vigilant for signs of secondary bacterial or fungal infection, such as increased erythema, tenderness, or systemic symptoms, which may require additional treatment.
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