Types of seborrheic dermatitis
Seborrheic dermatitis is a prolonged and often chronic skin disorder1 typically classified as a chronic eczema. It is also known as seborrhea but sometimes referred to and related to ear eczema, eyelid dermatitis, and diaper dermatitis. Symptoms include inflamed scaly, red, itchy and greasy skin. Areas most affected include areas high in sebum, or natural body oils, such as the face including the scalp, eyebrows, eyelids, areas adjacent to the nose and upper lip referred to as the nasolabial fold, underarm areas, below the breasts and in the groin, and also the upper buttocks.1It may cause issues with the self-esteem of an individual or socialization1as it frequently affects the head and neck.
Seborrheic dermatitis is thought to be the single most common skin inflammatory condition that affects humans’ besides acne and is thought to affect 2-5% of the population.
Who is at risk of seborrheic dermatitis?
Seborrheic dermatitis may be experienced by people of any age and ethnicity. This skin condition is triggered by a number of risk factors. Such include heat, sunlight, illnesses, skin irritants and chronic ailments such as Parkinson’s disease or viral infections such as HIV infection.
It should be noted that there is a specific type of seborrheic dermatitis that targets neonates and infants up to the age of 3. This is called infantile seborrheic dermatitis or cradle cap. Symptoms include the formation of greasy and scaly patches which eventually turn crusty and thick on the baby’s scalp. At times, red rashes may appear on the diaper region and elsewhere. It is commonly mistaken for a diaper rash. Infantile seborrheic dermatitis is typically a self-limited condition and resolves with time.
What causes seborrheic dermatitis and what are the different types?
Not much is known about the exact causes of seborrheic dermatitis. Because this condition occurs in oily regions of the skin surface, it is believed that the over-production of sebum may be a major causative factor of seborrheic dermatitis. Also, it appears that most patients of seborrheic dermatitis are highly afflicted with Malassezia or Pityrosporum¸ a common skin yeast. However, whether or not the fungi plays a causal role in seborrheic dermatitis remains to be determined. Patients who have some underlying disorders with the central nervous system have more trouble with seborrheic dermatitis. We are yet to understand whether or not the CNS plays any role in seborrheic dermatitis.
Seborrheic dermatitis may be classified into infantile and adult forms. However, there is overlap of the different types of seborrheic dermatitis as they typically affect different areas on the body.
Infantile seborrheic dermatitis also known as cradle cap
Infantile seborrheic dermatitispresents as greasy and thick scales occurring on the top of the scalp in very young children.2In infants, the condition is not typically itchy or red; it is simply extensively yellow, greasy, and scaly. There may be variations in the color of the scales, giving a white, yellow or off-white appearance. It typically presents during the first few weeks of life and typically resolves after 3 months of age. Infants who have dry and large scales may also have psoriasiform seborrheic dermatitis. This is a type of cradle cap that also has features of psoriasis. Sometimes, it is associated with a red rash all over the body which is called generalized seborrheic dermatitis. Thankfully, this condition is quite rare.
Adult seborrheic dermatitis
Adult seborrheic dermatitis typically begins as a greasy but mild scaling on the scalp (dandruff) and may also be accompanied by redness and formation of scales on the skin along the sides of the nose (nasolabial folds) continuing to the upper lip area. The same occurs on the skin behind the ears called the postauricular skin. Scaling occurs in areas with excess sebum secretion (such as the ears and ear canals, eyebrows, beard and the upper chest area). In some cases, the central region of the face may be involved.
There are other much less common variants of seborrheic dermatitis types which include eryrhroderma and petaloid seborrheic dermatitis.3The latter appears as scaly patches which take the shape of a medallion or a flower. Erythoderma has large red areas that may spread to cover the entire surface of the body. Thankfully, this rash is extremely rare.