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Seborrheic Dermatitis: Definition, Epidemiology, Etiopathogenesis, Clinical Manifestations

Definition

What is Seborrheic dermatitis? 

Seborrheic dermatitis or seborrheic eczema is a superficial chronic inflammatory disease characterized by reddish scales on the skin base. It often affects skin areas that have high sebum production and folds.

In 1984, Shuster stated that seborrheic dermatitis could be suppressed with systemic ketoconazole. These findings are related to a recent study that explained that seborrheic dermatitis is closely associated with the yeast Pityrosporum.

Seborrheic Dermatitis: Definition, Epidemiology, Etiopathogenesis, Clinical Manifestations
Scalp Seborrheic Dermatitis



Epidemiology

Seborrheic dermatitis is divided into two age groups:

  1. The infantile form resolves itself, especially in the first three months of life.
  2. The chronic adult form. 
Male predominance is seen at all ages, without preference for race, or horizontal transmission.

Characteristics Seborrheic dermatitis has a bimodal trend, with the first peak frequency at birth and the second in adults aged 30 to 60 years.9 Its prevalence is estimated to be 5%, but the lifetime incidence is significantly high. Extensive, treatment-resistant seborrheic dermatitis is an important cutaneous sign of HIV infection, Parkinson's disease, and mood disorders.


Etiopathogenesis

What are causes seborrhoeic dermatitis?

The etiopathogenesis of seborrheic dermatitis is partially known. Although the pathogenesis of Seborrheic dermatitis is not fully understood, it is thought that there is an association with excessive sebum production and the commensal yeast Malassezia.

Seborrheic dermatitis was first described by Unna, who suspected Malassezia furfur as a causative factor. This disease classification has been discussed for decades, focusing on sebaceous gland dysfunction and the high number of Malassezia furfur present in seborrheic dermatitis scales. Skin lipids and Malassezia species are the most studied etiological factors. There are no more sebaceous glands in seborrheic dermatitis patients than in healthy individuals. Also, there are no morphological abnormalities and gland size in patients with seborrheic dermatitis compared to healthy people.

Not everyone with Hyperborea has seborrheic dermatitis, but patients with seborrheic dermatitis can have a normal quantity of sebum or even dry skin. So it can be concluded that the amount of sebum is not a factor in seborrheic dermatitis.

In the sebum of patients with seborrheic dermatitis, triglycerides and cholesterol are increased, while squalane and free fatty acids are reduced. Free fatty acids known to have an antimicrobial effect are formed from triglycerides by bacterial lipases produced by Corynebacterium acne and Malassezia, which are resident flora. Free fatty acids and reactive oxygen radicals can alter the balance of the normal flora of the skin.

Malassezia species cannot produce fatty acids, which are essential for their growth. However, it produces lipases and phospholipases, which break down triglycerides into free fatty acids. Furthermore, the Malassezia species use saturated fatty acids and release unsaturated fatty acids to the skin's surface. Finally, these species induce the release of proinflammatory cytokines (IL6 and 8, and tumor necrosis factor α).

Relationship other medical conditions with seborrheic dermatitis

In AIDS patients, Seborrheic dermatitis is more frequent and severe. In AIDS patients, the prevalence of Seborrheic dermatitis ranges from 34% to 83% (in the general population, the prevalence is only 3-5%). These patients were mostly homosexual or bisexual men with CD4 + <400 / mm3. They suffer from Seborrheic dermatitis with more severe inflammation and desquamation. Furthermore, in AIDS patients, the burden of Malassezia spp is higher than in healthy people. This could be because these patients had a specific cellular deficiency for Malassezia spp. So it can be concluded that Malassezia spp has a role in the pathogenesis of seborrheic dermatitis. This is also indicated by the fact that oral antimycotics are useful as a therapy for Seborrheic dermatitis.

According to some literature, Seborrheic dermatitis is more common in patients with Parkinson's and facial palsy. Therapy with L-dopa will only reduce sebum secretion if there is excessive secretion, but it has no clinical impact on normal sebaceous gland secretion. However, several published studies suggest that L-dopa causes clinical improvement in seborrheic dermatitis.

Increased sebum pooling in immobility skin may be important in this case. Hot, humid environments and sweating are known to exacerbate Seborrheic dermatitis symptoms, especially itching of the scalp.

Sunlight and tropical climates can also exacerbate the symptoms of Seborrheic dermatitis. So these findings suggest that climatic conditions can affect the growth of Malassezia species. However, for further clarification, more specific studies are needed.


Clinical Manifestations

Clinical manifestations Seborrheic dermatitis often appears as well-defined:

  1. plaque erythema with an oily, 
  2. yellowish surface with various extensions to areas rich in sebaceous glands:
  • the scalp, 
  • retro auricular area, 
  • face (nasolabial folds, upper lip, eyelids, and eyebrows)
  • and inner chest.  
The distribution of the lesions is generally symmetrical, and Seborrheic dermatitis is neither contagious nor fatal.

In infants, seborrheic dermatitis can appear on the scalp, face, retro auricular, body folds; rarely be generalized. Cradle cap is the most frequent clinical manifestation. Seborrheic dermatitis in children usually resolves on its own. In contrast, seborrheic dermatitis in adults is usually chronic and recurrent. Itching is rarely felt but often occurs in lesions on the head. The main complication is the secondary bacterial infection, which increases redness, exudate, and local irritation.

However, in infants, it can also be aggravated by the expansion of skin lesions to more than 90% of the body area as erythroderma desquamation (Leiner disease). The clinical manifestations include fever, anemia, diarrhea, vomiting, weight loss, and can cause death.

In immunosuppressed patients, seborrheic dermatitis is often widespread, intense, and refractory to therapy. This may be considered an early cutaneous manifestation of AIDS in both children and adults.

Seborrheic dermatitis severity can be determined by the presence of erythema, scale, infiltration, and pustules. For each parameter, 4 points are used (0-none, 1-light, 2-moderate, 3-heavy). The second measurement is based on the percentage of the affected skin area, which is less than 10% (1 point), 10-30% (2 points), 30-50% (3 points), 5070% (4 points), and more than 70% (5 points). ). The results are obtained by multiplying the two measurements above, namely mild seborrheic dermatitis (total score is 5 or less), moderate Seborrheic dermatitis (total score 6-11), and severe seborrheic dermatitis (total score 12-60).

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