Seborrheic dermatitis is a common skin disease associated with increased and altered sebum production and yeast colonization. Seborrheic dermatitis presents as a chronic dermatitis or eczema in sebum rich areas of the body like scalp, face and upper trunk. Its milder, non-inflammatory form is known as dandruff.
Seborrheic Dermatitis affects 1-3% general population, though dandruff is a very common occurrence. More than 36% of HIV positive patients have Seborrheic Dermatitis.
What are the Causes for Seborrheic Dermatitis?
Seborrheic dermatitis appears in genetically pre-disposed individuals with the so called seborrheic diathesis, meaning increased sebum secretion in the sebaceous gland rich areas of the body- the scalp, face, front of chest, and in between the shoulder blades. Certain triggering agents make the greasiness of the skin in these areas a flourishing ground for the yeasts known as malassezia. These yeasts breakdown and alter the composition of the sebum which further sets in motion an inflammatory response in the skin. This in turn increases the sebum secretion and the cycle continues again.
The skin becomes red, irritated and scaly. Itching is prominent in acute, active state. In addition to the classical sites, seborrheic dermatitis can also affect the eyelids, armpits, groin and gluteal fold.
Malassezia species M.restricta and M.globosa have been isolated from the seborrheic dermatitis skin.
Seborrheic dermatitis is seen in the first few months of life when maternal androgens are present in the blood. Then, the disease re appears in susceptible individuals after the sebaceous glands become active during puberty.
Seborrheic dermatitis can be considered a part of the clinical spectrum between dandruff and psoriasis.
What are the Triggers for Seborrheic Dermatitis?
- Stress & Fatigue. Both lowered immunity and hormonal stimulation are the reasons for increased seborrheic dermatitis in stressed and fatigued conditions.
- Hormonal Triggers . Androgen hormones control the sebaceous activity in humans. Probably these are under the control of a sebotrophic hormone secreted from the hypothalamus. Body builders using anabolic steroids get severe attacks of seborrheic dermatitis.
- Environmental Triggers. Seborrheic dermatitis is precipitated in low humid conditions and in winter.
- Low Immune states. Either due to medications, or diseases like HIV and malignancies trigger seborrheic dermatitis.
- Food. Sugar consumption, fast foods, Vit B including B12 malutilization, biotin deficiency, niacin deficiency, pyridoxine deficiency, zinc deficiency and excess alcohol consumption have all been found to increase the incidence of seborrheic dermatitis .
- Drugs. Broad spectrum Antibiotics, OCP, Systemic Steroids, buspirone, chlorpromazine, cimetidine, ethionamide, griseofulvin, haloperidol, interferon alfa, lithium, methoxsalen, methyldopa, phenothiazines, psoralens, stanozolol are some of the medications that have been found to increase seborrheic dermatitis. The list is not complete.
- Diseases. Seborrheic dermatitis may be the presenting feature of Parkinsonism and HIV infection. Incidence of seborrheic dermatitis is high in epilepsy, idiopathic post encephalitis, diabetes mellitus, paralytic states etc.
What are the Other Causes for Itchy Scalp?
Seborrheic dermatitis has to be differentiated from scalp dryness, contact allergy and psoriasis, all of which cause itchy and scaly scalp.
What are the Types of Seborrheic Dermatitis?
- Infantile Seborrheic Dermatitis
- Craddle cap
- Trunk: Flexural, napkin (diaper) area
- Leiner’s disease
- Adult Seborrheic Dermatitis
- Scalp: Dandruff and inflammatory types.
- Face: Inflammatory and non inflammatory, with blepharitis(eye lid)
- Trunk: Petaloid, pityriasiform, follicular, follicular, eczematous type
- Generalized exfoliative erythroderma
What are the Complications of Seborrheic Dermatitis?
- Psychosocial impact: Chronic visible disease may affect a person's self esteem.
- Secondary bacterial infection with Staphylococcus aureus may occur, with typical impetigo with increased redness, oozing and crusting.
What is Leiner’s Disease?
Leiner's disease is a complication of seborrheic dermatitis in infants with C5 complement deficiency. There is usually a sudden confluence of lesions leading to a generalised scaling and redness of the skin. The child is severely ill with anemia, diarrhea and vomiting. Secondary bacterial infection is common.
Related Reading
Reference
Hanish Babu - Dr.Hanish Babu, MD is a dermatologist and a feature writer on Suite101.com with more than 200 articles related to skin diseases on the ...
Join the Conversation