Seborrheic Dermatitis Comprehensive Notes

Seborrheic Dermatitis: General Information and Historical Context

• Historically, seborrheic dermatitis was first described by Dr. Unna in the late 1890s.

• It's a common inflammatory skin disorder classified within the papulosquamous category.

• It occurs in areas with increased sebaceous gland activity, such as:

  • Scalp

  • Face

  • Perioricular region

  • Presternal area

  • Intertriginous areas

Association with Yeast and Other Factors

• Specific yeast, like Pityrosporum ovale (now known as Malassezia), are associated with seborrheic dermatitis.

• The exact mechanism is unclear, but research suggests possible abnormal responses to this yeast, including:

  • T cell depression

  • Alternate complement activation

  • Increased sebum production

• Increased stress is also linked to increased activity of seborrheic dermatitis.

Prevalence, Diagnosis, and Age Groups

• Seborrheic dermatitis typically presents with intermittent activity and periods of remission.

• Worldwide prevalence is approximately 3-5%, with mild cases potentially reaching 20%.

• Diagnosis is primarily clinical, as there are no specific helpful laboratory tests.

• It commonly affects two primary age groups:

  • Infants: Occurring within the first few days or weeks of life, typically resolving within 3-6 months and is often self-limiting.

  • Adults: The most common presentation, affecting an estimated 5% of adults.

Impact of Hospitalization and Specific Patient Groups

• Brief hospitalizations can trigger temporary outbreaks, possibly due to increased body stress altering normal immune function.

• Higher incidence is observed in patients with:

  • Parkinson's disease

  • History of alcohol abuse

Physical Exam Findings

• Physical exam findings differ based on age.

• Disease occurs at sites of increased sebaceous glands.

  • Face: Approximately 500 glands per $cm^2$

  • Neck: Approximately 250 glands per $cm^2$

  • Dorsum of hand: Less than 75 glands per $cm^2$

• Severity is typically mild, but some cases can be widespread.

• Rarely, patients may present with erythrodermic seborrheic dermatitis involving the entire body.

• HIV patients can experience severe and recalcitrant disease.

• Patients with type six skin may sometimes have annular-appearing lesions.

Physical Exam in Infants

• Typically appears during the 2nd to 10th week of life, with peak incidence at 3 months.

• Scalp is the most common site of involvement; when extensive, it's termed cradle cap.

• Other locations: face, retroauricular region, neck, trunk, groin, and proximal extremities.

• Primary lesions: Faint plaques

• Secondary lesions: Diffuse scale and erythema

• Description: Scaling plaques over red inflamed skin, often symmetrical with red to pink or brown greasy quality.

• Key feature: Typically no hair loss.

• Seldom see excoriations as itching is minimal, distinguishing it from atopic dermatitis.

• Cradle cap: Patchy, scaly, sometimes crusty, greasy skin rash on the scalp of newborns and infants.

Physical Exam in Adults

• Distribution involves the scalp and face in a symmetrical pattern.

• Scalp: Any area can be involved, but parietal and temporal regions are more frequent.

• Face: Paranasal areas, nasolabial creases, and eyebrows are commonly involved.

• Other areas of involvement:

  • Midface

  • Perioral area

  • Eyelid region (upper and lower), sometimes with edema and scale on the upper eyelids.

Additional Areas of Involvement in Adults

• Perioricular area

• Postauricular sulcus and surface.

• Midline area of the chest

• Less often in intertriginous areas

• Primary lesions: Fine plaque with scale and erythema.

Important Characteristics of Lesions

• Margins of lesions are not distinct.

• May only see slight scaling.

• Intermittent activity is typical; recurrences are the norm.

• Patients typically don't complain of itching.

• Alopecia is uncommon.

• More commonly seen in certain geriatric conditions, including Parkinson's disease and chronic alcoholism.

• Patients with HIV infection may have severe and recalcitrant cases.

• Blepharitis (eyelid margin involvement): Characterized by erythema and scale on the lashes.

Common Associated Findings with Seborrheic Dermatitis

• Non-melanoma skin cancer (basal cell carcinoma and squamous cell carcinoma)

• Actinic keratosis

• Rosacea

• Management may involve clearing up seborrheic dermatitis before treating actinic keratoses.

Management Strategies

• Encourage patients to treat at the first sign of flare-up.

• Treatment plans are based on regional involvement.

Scalp

• Mild to moderate cases: Anti-dandruff shampoos containing:

  • Tar preparations

  • Zinc pyrithione

  • Anti-yeast azole products (e.g., ketoconazole or Nizoral).

• Moderate to severe cases: Low to mid-potency topical steroid solutions (or stronger if necessary).

• Derma-Smooth FS oil shampoo: For thick, adherent scales.

  • Apply nightly to damp scalp, cover with a shower cap, and shampoo out the next morning.

  • Repeat nightly for up to 7 days; improvement is rapid.

• Type six skin considerations:

  • Dry scalps require reduced shampoo frequency.

  • Topical steroid ointments may be preferred for moisturizing.

Face

• Mild to moderate cases: Non-fluorinated topical steroid creams, lotions, or ointments.

• Ketoconazole cream 2%: Excellent product, used once or twice daily.

• Topical calcineurin inhibitors (e.g., Protopic ointment, Elidel cream): Very effective.

• Topical metronidazole gel: For refractory cases.

• Severe cases: Systemic ketoconazole 200 mg/day or Diflucan 200 mg/day for 1-2 weeks.

Torso

• Low to mid-potency topical steroids (e.g., triamcinolone 0.1%)

• Topical calcineurin inhibitors

• Anti-Pityrosporum shampoos

Infants

• Prognosis is good; clears in weeks with simple or no treatment.

• Scalp: Treat by shampooing.

  • Use baby shampoos, gently massage into scalp.

  • Rarely, non-fluorinated topical steroid solutions or lotions (if significant inflammation is present), sparingly once or twice daily.

• Body/intertriginous/diaper areas:

  • Barrier products with zinc oxide: Function as a protective barrier in the diaper area.

  • Non-fluorinated topical steroid creams (e.g., 1% hydrocortisone cream): applied sparingly and rubbed in completely; can be mixed with a bland emollient. The younger the patient, the greater the emollient concentration

    • Example for newborn with severe seborrhea: three parts moisturizing cream and one part hydrocortisone cream.

    • Mix thoroughly in a clean container and apply to affected areas as needed (once, twice, or even three times daily).

    • Increase moisturizer amount as rash improves.

Scalp Therapy for Patients with Skin of Color

• Management poses unique challenges due to scalp dryness.

• African American scalps tend to be substantially drier.

• Women with curly, tightly coiled, relaxed hair:

  • Shampoo twice weekly with anti-seborrheic shampoos.

  • Limit product contact time to 5 minutes.

  • Follow with a moisturizing conditioner for 5-10 minutes.

Differentiating Seborrheic Dermatitis from Other Rashes

Atopic Dermatitis Comparison

Infantile Seborrheic Dermatitis vs. Atopic Dermatitis:

• Seborrheic Dermatitis:

  • Earlier age of onset

  • More scalp involvement

  • Less inflammation or redness

  • Lacks vesicular lesions and oozing

  • Typically lacks itching and secondary infection

  • Self-limiting

  • Absence of allergic rhinitis and asthma

  • Diaper area and scalp involvement without face and other flexural involvement, combined with the absence of itching favors seborrheic dermatitis.

• Overlap can occur; atopic dermatitis features become more prominent as seborrheic dermatitis features subside.

Adults Seborrheic Dermatitis vs. Adult Atopic Dermatitis

• Patients with seborrheic dermatitis characteristically have scalp involvement and lack itching.

• Patients also lack generalized dryness classically seen with atopic dermatitis.

Seborrheic Dermatitis vs. Psoriasis

• Patients may have clinical features of both, termed seborrheic psoriasis.

• Psoriasis features: defined plaque with scale, sharper edge and thickened scale; plaque is well circumscribed and raised; discrete erythematous plaques

Key Differences:

• Seborrheic Dermatitis:

  • More flexural than extensor involvement

  • Scalp involvement typically stays within the scalp region

  • Fine scale

• Psoriasis:

  • May extend beyond the scalp

  • Adherent silvery scale

  • Potentially more resistant to improvement with treatment

Seborrheic Dermatitis vs. Tinea Infections (Scalp)

• Consider tinea capitis when anti-seborrheic treatment protocols fail.

Tinea Capitis Indicators:

• Hair loss is typically present

• Lymphadenopathy may be present

• Pustules or boggy nodules suggest kerion formation

• Annular primary lesions with peripheral fine scale

• Diagnosis via KOH preps of hair or fungal cultures.

Non-Improving Seborrheic Dermatitis

Infantile Seborrheic Dermatitis:

• Severe cases that don't improve with standard measures and are associated with crusted papules, lymphadenopathy, and hepatosplenomegaly: consider:

  • Histiocytosis X

  • Various immunodeficiencies

  • Zinc deficiency

Adult Seborrheic Dermatitis:

• Number one consideration: HIV infection

Additional Considerations:

• Other papulosquamous diseases:

  • Psoriasis

  • Pityriasis rosea

  • Intertrigo

  • Parapsoriasis

  • Subacute cutaneous lupus

• Infiltrative disorders:

  • Sarcoidosis

  • Cutaneous T-cell lymphoma

Seborrheic Dermatitis in HIV Patients:

• Exaggerated involvement

• Widespread lesions

• Thickened plaque and scale

• Areas of hyperpigmentation

• Noticeable treatment resistance