Learning Objectives
Identify the classic clinical features of Seborrheic Dermatitis, including its characteristic “greasy” appearance and predilection for sebaceous-rich areas. Master the systemic associations, specifically HIV and Parkinson’s disease, and understand the role of Malassezia spp. in its pathogenesis.
1. Clinical Characteristics & Presentation
Seborrheic dermatitis is a common inflammatory condition that affects areas of the body with a high density of oil-producing glands. It presents differently across age groups but maintains a consistent “greasy” morphology.
| Feature | Description | High-Yield Color/Texture |
|---|---|---|
| Morphology | Erythematous, well-demarcated plaques. | Greasy yellow scales. |
| Distribution | Scalp (dandruff), eyebrows, chest, and nasolabial folds. | Areas rich in sebaceous glands. |
| Infant Form | Known as “Cradle Cap”. | Usually self-limiting. |
2. Pathophysiology & Systemic Associations
While the exact cause is not fully understood, the condition is strongly linked to the presence of skin flora and specific underlying neurological or immunological states.
| Category | Associated Factor | Clinical Context |
|---|---|---|
| Microbiology | Malassezia spp. | A yeast-like fungus that thrives on sebum. |
| Neurological | Parkinson Disease | Increased incidence and severity of dermatitis. |
| Immunological | HIV Infection | An extensive or “explosive” onset may be a sentinel sign of HIV. |
3. Management & Treatment
Treatment focuses on reducing the fungal load and calming the associated inflammation.
| Therapy Type | Action |
|---|---|
| Topical Antifungals | Target the Malassezia (e.g., ketoconazole). |
| Topical Glucocorticoids | Reduce inflammation and erythema. |
Activity: Clinical Correlations
- Seborrheic = Sebaceous (oil) glands + Scales (yellow/greasy).
- HIV & Parkinson: If a patient has unusually severe dandruff or facial redness, check for HIV or Parkinson’s.
- Malassezia: This is the same fungus associated with Tinea Versicolor.