Seborrhoeic Dermatitis

Introduction | Aetiology and Risk Factors | Clinical Presentation | Diagnosis | Management and Treatment | Prevention | When to Refer | References

Introduction

Seborrhoeic dermatitis is a common, chronic inflammatory skin condition that primarily affects areas of the body with a high density of sebaceous (oil) glands, such as the scalp, face, and upper chest. It is characterised by red, scaly, and sometimes itchy patches. The exact cause is not fully understood, but it is thought to be related to the overgrowth of a yeast called Malassezia, in combination with individual susceptibility. Seborrhoeic dermatitis is often recurrent and can be managed with appropriate treatments.

Aetiology and Risk Factors

Seborrhoeic dermatitis is thought to result from a combination of factors:

• Malassezia Yeast: The overgrowth of this yeast on the skin is a key factor. It feeds on skin oils and is found in areas with a high density of sebaceous glands.
• Skin Oil (Sebum) Production: Increased production of sebum creates an environment conducive to yeast overgrowth, contributing to inflammation and scaling.
• Immune Response: An abnormal immune response to Malassezia may lead to the inflammation seen in seborrhoeic dermatitis.
• Genetic Predisposition: A family history of seborrhoeic dermatitis or other skin conditions like psoriasis may increase the risk.
• Environmental Factors: Cold, dry weather and stress can exacerbate the condition.
• Neurological and Psychiatric Conditions: Conditions such as Parkinson's disease and depression have been associated with a higher incidence of seborrhoeic dermatitis.

Clinical Presentation

Seborrhoeic dermatitis typically presents with the following features:

• Scaly Patches: Greasy, yellowish or white scales on a red, inflamed base are commonly found on the scalp, eyebrows, nasolabial folds, and chest.
• Itching: Itching is common but may vary in severity.
• Dandruff: On the scalp, seborrhoeic dermatitis often presents as dandruff, with flaking of the skin.
• Crusting: In more severe cases, thick crusts may form, particularly on the scalp.
• Distribution: The condition typically affects the scalp, face (especially around the nose and eyebrows), ears, chest, and upper back.
• Fluctuating Course: Symptoms often improve and then recur, particularly in response to environmental changes or stress.

Diagnosis

The diagnosis of seborrhoeic dermatitis is primarily clinical, based on the characteristic appearance and distribution of the lesions:

• History: Take a detailed history, including the onset and duration of symptoms, any known triggers (e.g., stress, weather changes), and response to previous treatments.
• Physical Examination: Examine the affected areas for typical red, scaly patches, especially in seborrhoeic regions like the scalp, face, and chest.
• Differential Diagnosis: Consider other conditions such as psoriasis, atopic dermatitis, rosacea, and contact dermatitis, which can present with similar features.
• Skin Biopsy: A skin biopsy is rarely needed but may be performed in atypical cases to rule out other conditions.

Management and Treatment

Management of seborrhoeic dermatitis involves controlling the symptoms through a combination of antifungal treatments, anti-inflammatory agents, and supportive care:

1. Antifungal Treatment

• Ketoconazole Shampoo: Ketoconazole 2% shampoo is the first-line treatment for seborrhoeic dermatitis affecting the scalp. It should be used twice a week for 2-4 weeks, then as needed to maintain control. It can also be used on other affected areas such as the face and chest.
• Other Antifungal Shampoos: Alternatives to ketoconazole include selenium sulphide, coal tar, and zinc pyrithione shampoos, which can also be effective in managing scalp symptoms.

2. Topical Steroids

• Betamethasone Valerate Scalp Application (Betacap): For more severe or resistant cases, betamethasone valerate 0.1% (Betacap) can be applied to the scalp to reduce inflammation. This should be used sparingly and for short periods to avoid side effects associated with long-term steroid use.
• Low-Potency Steroids: For facial or other sensitive areas, mild topical corticosteroids like hydrocortisone 1% may be used short-term to control inflammation.

3. Topical Calcineurin Inhibitors

• Tacrolimus or Pimecrolimus: These are non-steroidal options that can be used on sensitive areas like the face where long-term steroid use is a concern. They are effective in reducing inflammation and are particularly useful for maintenance therapy.

4. Supportive Care

• Regular Cleansing: Advise patients to wash the affected areas regularly with a gentle, non-irritating cleanser to remove scales and reduce oiliness.
• Moisturising: Use of non-comedogenic moisturisers can help soothe the skin and reduce scaling, particularly on the face.
• Sunlight Exposure: Moderate sun exposure can help improve symptoms, although patients should avoid excessive exposure and always use appropriate sun protection.

Prevention

Preventive strategies are key to managing seborrhoeic dermatitis and reducing the frequency of flare-ups:

• Maintenance Therapy: Continue using antifungal shampoos like ketoconazole once a week or every other week to prevent recurrence.
• Avoid Known Triggers: Stress management and avoiding harsh skincare products can help prevent flare-ups.
• Regular Skin Care Routine: Maintain a gentle skincare routine using non-irritating, fragrance-free products to keep the skin balanced and healthy.

When to Refer

Referral to a dermatologist may be necessary in the following situations:

• Severe or Refractory Cases: If seborrhoeic dermatitis does not respond to standard treatments or if the condition is severe, referral to a specialist is advised.
• Complications: If there are complications such as secondary infection or significant discomfort, specialist input may be required for further management.
• Uncertain Diagnosis: If the diagnosis is unclear or if there is concern for other underlying conditions, a dermatologist's input may be necessary.

References

1. British Association of Dermatologists (2024) Guidelines for the Management of Seborrhoeic Dermatitis. Available at: https://www.bad.org.uk (Accessed: 26 August 2024).
2. National Institute for Health and Care Excellence (2024) Seborrhoeic Dermatitis: Diagnosis and Management. Available at: https://www.nice.org.uk/guidance/ng105 (Accessed: 26 August 2024).
3. British National Formulary (2024) Topical and Oral Treatments for Dermatological Conditions. Available at: https://bnf.nice.org.uk/ (Accessed: 26 August 2024).