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Seborrheic dermatitis could be the cause of your recent dandruff outbreak

November 14, 2017

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  • Mainly affects the sebaceous, gland-rich regions of the scalp, face, and trunk, seborrhoeic or seborrheic dermatitis is a common, chronic or relapsing form of eczema/dermatitis. There are infantile and adult forms of seborrhoeic dermatitis. It is sometimes associated with psoriasis (sebopsoriasis). Seborrhoeic dermatitis is also known as seborrhoeic eczema.
  • Dandruff also known as pityriasis capitis is considered to be an uninflamed form of seborrhoeic dermatitis. Scattering within hair-bearing areas of the scalp, dandruff of such presents as itself as bran-like scaly patches.
  • Although the cause of seborrhoeic dermatitis is not completely understood, it is associated with proliferation of various species of the skin commensal Malassezia, in its yeast, non-pathogenic form. Its metabolites (such as the fatty acids oleic acid, malssezin, and indole-3-carbaldehyde) may cause an inflammatory reaction. Differences in skin barrier lipid fuction and content may account for individual presentations.
  • Adult seborrhoeic dermatitis tends to begin in late adolescence. It is less common in females than in males and most common amongst young adults and in the elderly.
  • The following factors are sometimes associated with severe adult seborrhoeic dermatitis:
    – A family history of psoriasis or familial tendency to seborrhoeic dermatitis
    – Oily skin (seborrhoea)
    – Lack of sleep, and stressful events.
    – Immunosuppression: organ transplant recipient, human immunodeficiency virus (HIV) infection and patients with lymphoma
    – Neurological and psychiatric diseases: congenital disorders such as Down syndrome, depression, epilepsy, facial nerve palsy, tardive dyskinesia, parkinson disease, spinal cord injury
    – Psoralen and ultraviolet A (PUVA) therapy used in treatments for psoriasis
  • Infantile seborrhoeic dermatitis is the type of seborrhoeic dermatitis that affects babies under the age of 3 months and usually resolves by 6–12 months of age. Its causes cradle cap, the diffuse greasy scaling on scalp. The rash may spread to affect armpit and groin folds resulting in a type of napkin dermatitis. They are characterised by their flaky or peeling salmon-pink patches. Since it is not itchy, babies often appear undisturbed by the rash, even when generalised.
  • As seborrhoeic dermatitis often affects the upper trunk, facial areas such as within eyebrows, around the nose and behind ears and scalp, typical features of this condition include:
    – Winter flares, improving in summer following sun exposure
    – Minimal itch most of the time
    – Combination oily and dry mid-facial skin
    – Ill-defined localised scaly patches or diffuse scale in the scalp
    – Blepharitis: scaly red eyelid margins
    – Ill-defined, thin, scaly and salmon-pink plaques in skin folds on both sides of the face
    – Ring-shaped or petal-shaped flaky patches on anterior chest or hair-line
    – Rash in armpits, under the breasts, in the groin folds and genital creases
    – Superficial folliculitis (inflamed hair follicles) on cheeks and upper trunk
  • Pityriasiform seborrhoeide is a form of extensive seborrhoeic dermatitis that affects the scalp, neck and trunk
  • Seborrhoeic dermatitis is often diagnosed by its clinical appearance and behaviour. This is because Malassezia is a normal component of skin flora. Due to this, their presence on microscopy of skin scrapings is often not diagnostic.
  • Although skin biopsy may be helpful but is rarely indicative. Histological findings specific to seborrhoeic dermatitis are as following:
    – superficial perivascular and perifollicular inflammatory infiltrates
    – psoriasiform hyperplasia
    – parakeratosis around follicular openings.
  • Treatment of seborrhoeic dermatitis often involves several of the following options:
    – Keratolytics can be used to remove scale when necessary, eg salicylic acid, lactic acid, urea, propylene glycol
    – To reduce Malassezia, topical antifungal agents such as ketoconazole, or ciclopirox shampoo or and/or cream are applied. It is important to note that some strains of Malassezia are resistant to azole antifungals. In such cases, it is advised to try zinc pyrithione or selenium sulphide, under a dermatologist supervision.
    – Mild topical corticosteroids are prescribed for 1–3 weeks to reduce the inflammation of an acute flare
    – Topical calcineurin inhibitors (pimecrolimus cream, tacrolimus ointment) are indicated if topical corticosteroids are often needed, as they have fewer adverse effects on facial skin
    – In resistant cases in adults, oral itraconazole, tetracycline antibiotics or phototherapy may be recommended. Low dose oral isotretinoin has also been shown to be effective for severe or moderate seborrhoeic dermatitis.
  • Scalp treatments include the following:
    – Medicated shampoos containing zinc pyrithione, selenium sulfide, coal tar, ciclopirox, ketoconazole and salicylic acid should be used twice weekly for at least a month
    – Steroid scalp applications are seen to reduce itching. These should be applied daily for a few days every so often.
    – Calcineurin inhibitors such as tacrolimus can be used as steroid alternatives.
    – Coal tar cream can be applied to scaling areas and removed several hours later by shampooing.
    – Combination therapy is often advisable.
  • Treatment for face, ears, chest and back affected by seborrhoeic dermatitis include:
    – Using a non-soap cleanser, cleanse the affected skin thoroughly once or twice each day.
    – Apply ciclopirox cream or ketoconazole once daily for 2 to 4 weeks, repeated as necessary.
    – Hydrocortisone cream can also be used, applied up to twice daily for 1 or 2 weeks. Occasionally a more potent topical steroid may be prescribed.
    – Topical calcineurin inhibitors such as pimecrolimus cream or tacrolimus ointment may be used instead of topical steroids.
    – A variety of herbal remedies are commonly used, but their efficacy is uncertain.
    – Regular washing of the scalp with baby shampoo or aqueous cream is followed by gentle brushing to clear the scales.
    – White petrolatum may be useful.
    – Depending on the extent of the rash, topical antifungals are often prescribed.

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Meet with Dr. Teo Wan Lin, consultant dermatologist at TWL Specialist Skin & Laser Centre, for a thorough consultation to determine the most suitable treatment for your skin.

To book an appointment with Dr. Teo, call us at +65 6355 0522, or email appt@twlskin.com. Alternatively, you may fill up our contact form here.

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