What is Seborrheic Dermatitis?
Before we share about the effectiveness of TCM for Seborrheic Dermatitis, let’s go over what Seborrheic Dermatitis is.
- Seborrheic Dermatitis is a skin condition linked to sebum production by the sebaceous glands.
- The skin lesions often show up as greasy and scaly patches. The areas of the body most affected are those rich in sebaceous glands — this includes the scalp, face, upper back, and for some people, the groin and armpit.
As you read on, you will realize it is sometimes not so straight forward, how Seborrheic Dermatitis is diagnosed. It is often confused with skin conditions as disparate as Fungal Infection, Rosacea, Atopic Dermatitis, Psoriasis, Pityriasis Rosea and even Pityriasis Versicolor.
Adult Seborrheic Dermatitis
There are two common classifications of Seborrheic Dermatitis in Chinese Medicine. They relate specifically to:
- Seborrheic Dermatitis of the Scalp
- Seborrheic Dermatitis of the Face.
Seborrheic Dermatitis of the Scalp is called Bai Xiao Feng (White Scales Wind) in Chinese Medicine. It starts with dandruff of the scalp, which then extends beyond the hairline (this is called “Corona Seborrhica”). It may also spread behind the ears, leading to greasy scale and fissures behind the ears. At a later stage, there may be reversible hair loss.
Seborrheic Dermatitis of the Face is called Mian You Feng (Roving Face Wind). The areas that are affected include the inner eyebrow, the eyelids (blepharitis), the nasolabial folds, and may spread all over the face.
Other areas affected in adult Seborrheic Dermatitis
Seborrheic Dermatitis of the Torso is often seen in on the chest and in the upper back of men. These is where sebum is rich where there are abundant hair follicles.
Seborrheic Dermatitis of the Groin and Armpit may show up as red and sensitive skin, but may also turn into weepy lesions.
What is Malassezia?
Malassezia is a type of yeast that naturally occurs in the skin’s oils. When it multiplies more than usual, it may cause an inflammatory response in the skin, which then triggers excessive oil production.
What is Sebum?
Sebum is this sticky and oily substance that our body produces in order to keep the skin moisturized. Sebum is made up of fat molecules, wax and squalene.
What are Sebaceous Glands?
Sebaceous glands are sebum-secreting glands that are concentrated on the face, back and chest.
Sebaceous gland activity is stimulated by androgens (sex hormones including testosterone and dihydrotestosterone), which explains why men are twice as likely than women to develop Seborrheic Dermatitis.
What is interesting is this: High sebum activity gives rise to Seborrheic Dermatitis and Acne, yet its presence is disproportionately low in Atopic Dermatitis and Eczema!
What are some factors that put you at risk?
- Male gender and increased androgen activity
- Poor skin and hair care practices
- Hot and humid weather conditions
5 Phases of Seborrheic Dermatitis
The pathogenesis of this condition can be categorized into five different phases.
- Sebaceous glands secrete lipids onto the skin surface.
- Malassezia yeasts colonizes areas that are covered with lipids.
- Lipase (an enzyme) is secreted by Malassezia, resulting in the generation of free fatty acids (FFA) and lipid peroxides that activate the inflammatory response.
- The immune system generates cytokines, such as IL-1α, IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12 and TNF-α. This stimulates keratinocyte proliferation and differentiation.
- Skin barrier disruption with resulting clinically evident erythema, pruritus and scaling.
Seborrheic Dermatitis or Eczema?
Seborrheic Dermatitis lesions sometimes look like Atopic Dermatitis / Eczema lesions. One reason is that The main reason why they can be similar is because the same commensal yeast lives off both Seborrheic Dermatitis and Eczema lesions. This yeast is called Malassezia or Pityrosporum.
Over time, some Seborrheic Dermatitis lesions around the ears may fissure and resemble the cracks you see in Eczema. Those around the upper back may erode and crust and show up like the erosions and crusts common in Eczema lesions.
The differences are most obvious in infants:
- Itch: In an infant, eczema is always itchy, and the child tends to be upset by the rash, with scratch marks being a common finding. Meanwhile, Seborrheic Dermatitis isn’t always itchy for infants.
- Area affected: Seborrheic Dermatitis may often spread to the diaper area in infants, while eczema in infant do not usually affect the buttocks.
Seborrheic Dermatitis or Psoriasis?
In fact, Malassezia is also present in Psoriasis, making it sometimes very difficult to differentiate Seborrheic Dermatitis from Psoriasis (More on TCM for Psoriasis here!)
Both Psoriasis in its nascent phase and Seborrheic Dermatitis may show up as greasy, scaly patches along the hairlines, around the ears, near the inner eyebrow.
That said, there are some ways to differentiate Psoriasis from Seborrheic Dermatitis:
- Look and feel: Once they develop beyond the nascent phase, Psoriasis lesions tend to show up as thicker, with a clearer border than Seborrheic Dermatitis lesions.
- Scales: Psoriasis scales are often less greasy, and drier.
- Auspitz sign: If you try to scratch or pluck off psoriasis scales, they will probably bleed and become thicker and itchier. On the other hand, SD patches are usually easy to remove with no bleeding.
- Colour: Psoriasis can appear as red or pink with silver-white scales, while the scales in SD tend to be more pinkish-yellow with yellowish flakes and a greasy appearance.
- Area affected: Psoriasis tends to extend beyond the hairline and usually affects more than one area of the body. If you have Scalp Psoriasis, you may have mild psoriasis on your elbows, knees or lower back too.
- Nail Changes: You are more likely to see nail pitting or dents in a mature Psoriasis presentation.
- Arthritis: About one-third of people with psoriasis get a form of arthritis as the disease gets worse. This pain can be classified as rheumatic pain and is also autoimmune in origin. Seborrheic Dermatitis is not an autoimmune skin condition.
When it is hard to differentiate both of them, there is also a medical label called Sebopsoriasis! For real!
Seborrheic Dermatitis or Rosacea?
If a person presents only with Seborrheic Dermatitis of the Face, it can be difficult to differentiate from Rosacea.
- Color: Rosacea tends to present as blushing or flushing with visible blood vessels on the face, while Seborrheic Dermatitis typically appears as yellow greasy patches.
- Flushing: Rosacea most prominent characteristic is telangiectasia, which widening of the tiny blood vessels on the face. These dilated blood vessels cause threadlike red lines or patterns on the skin. Seborrheic Dermatitis does not present like this, and just appears as dull pink.
- Areas affected: Seborrheic Dermatitis often affects the forehead and eyelids, while Rosacea lesions usually start out at the sides of the nose and cheeks.
- Bumps: Rosacea lesions are also more ‘bumpy’ and ‘pimply’ compared to the flat and scaly lesions seen in Seborrheic Dermatitis.