Symptoms and Causes
Seborrheic Dermatitis
Seborrheic dermatitis manifests through a range of symptoms, primarily affecting the scalp but also appearing on other oil-rich areas of the body. The common symptoms include:
- Scalp Symptoms: Persistent dandruff characterized by flaky white or yellow scales. This dandruff can mix with hair and fall onto the neck and shoulders.
- Facial Symptoms: Red, scaly patches, particularly around the eyebrows, sides of the nose, and behind the ears.
- Body Symptoms: Patches on the chest, upper back, armpits, groin, and beneath the breasts. These patches may be salmon-pink in color and can flake or peel.
In infants, seborrheic dermatitis is known as cradle cap, which presents as crusty yellow scales on the head, possibly spreading to armpit and groin folds. Unlike in adults, infants usually do not experience itching, although the condition can cause inflammation if scratched. In adults, the condition is often characterized by a combination of oily and dry skin patches, minimal itching, and ill-defined localized scaly patches or diffuse scales on the scalp.
The exact cause of seborrheic dermatitis is not fully understood, but several factors are believed to contribute to its development, including:
- Malassezia Yeast: This yeast is present on all skin but can overgrow in some individuals, leading to inflammation. The yeast produces lipases and phospholipases that break down sebum, releasing free fatty acids that can cause irritation and inflammation.
- Sebum Production: High levels of skin oils can contribute to the condition, providing a rich environment for the overgrowth of Malassezia.
- Genetic Factors: A family history of seborrheic dermatitis or psoriasis increases the risk of developing the condition.
- Environmental Factors: Stress, cold and dry climates, and certain medications can exacerbate symptoms. Additionally, an increase in androgens (hormones) and variations in skin barrier lipid content and function may also play a role.
Other factors that may trigger or worsen seborrheic dermatitis include the use of alcohol-based lotions, a history of other skin disorders (such as rosacea, psoriasis, and acne), and underlying health conditions such as Parkinson’s disease, HIV, and neurological and psychiatric disorders.
