Distinguishing Scalp Psoriasis, Seborrheic Dermatitis and Dandruff

February 14, 2024

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Itchy, flaky scalps are very common, but determining the exact cause can be confusing. The most prevalent culprits are scalp psoriasisseborrheic dermatitis and dandruff (mild seborrheic dermatitis). While their signs and symptoms overlap, understanding key differences helps guide appropriate treatment.

Defining Scalp Psoriasis

Scalp psoriasis stems from an abnormal immune response causing rapid skin turnover. This results in a buildup of thick, dry scales that shed easily and are brighter white. The extra skin layer also blocks hair follicles leading to temporary hair loss in patches.

In addition to itching and flaking, scalp psoriasis has more severe redness, swelling and tenderness compared to other scalp issues. Areas also feel thicker and rougher with clearly demarcated borders.

About half of those with scalp psoriasis concurrently battle plaques on elbows, knees, lower back and nails. There is no cure, but various treatments aim to minimize symptoms and improve quality of life.

Overview of Seborrheic Dermatitis

Seborrheic dermatitis is thought to involve a reaction to a common skin yeast called Malassezia. This triggers flares consisting of greasy yellow to white scales and dandruff accompanied by itchiness and mild redness.

Distribution sticks to oilier areas like the scalp, face, upper chest and wherever skin folds. Infants often get cradle cap. Symptoms naturally wax and wane but worsen in cold, dry weather when skin barrier function falters.

Anti-yeast and anti-inflammatory agents reduce outbreaks. With diligent skin care, seborrheic dermatitis generally remains controlled but may persist lifelong with periodic flares.

Dandruff as Mild Seborrheic Dermatitis

The term dandruff refers to flaky scaling limited to the scalp without significant redness or inflammation. It falls on the very mild end of the seborrheic dermatitis spectrum.

Dandruff reflects an irritated scalp reacting to factors like infrequent shampooing, harsh products, dry cold air and stress. Oily white flakes easily brush out but regenerate quickly. Anti-dandruff shampoos adequately treat most cases.

So in essence, dandruff represents incidental, situational seborrheic dermatitis that comes and goes while seborrheic dermatitis consists of recurring scalp flares of various degrees.

Distinguishing Features of Scalp Psoriasis vs Seborrheic Dermatitis vs Dandruff

Scalp psoriasis can prove challenging to differentiate from seborrheic dermatitis to an untrained eye, but dermatologists utilize the following characteristics:

Location

  • Scalp psoriasis – any location including behind ears and nape of neck
  • Seborrheic dermatitis – scalp, central face, ears, upper back/chest
  • Dandruff – restricted to the scalp only

Appearance

  • Scalp psoriasis – thick silvery white scales, well-demarcated edges
  • Seborrheic dermatitis – yellow greasy scales, poorly defined borders
  • Dandruff – thin powdery flakes

Inflammation

  • Scalp psoriasis – marked redness, swelling and tenderness
  • Seborrheic dermatitis – mild to moderate pinkness
  • Dandruff – no redness

Scale Adherence

  • Scalp psoriasis – firm, strongly attached scales
  • Seborrheic dermatitis – loose scales shed easily
  • Dandruff – detaches readily

Symptoms Over Time

  • Scalp psoriasis – lifelong relapsing condition
  • Seborrheic dermatitis – fluctuates in severity longterm
  • Dandruff – temporary, comes and goes

Treating Scalp Psoriasis

Since scalp psoriasis relates to an overactive immune system, treatments aim to:

  • Soothe inflammation
  • Slow skin cell turnover
  • Remove scales to clear blockages

Common methods include:

Topical Steroids

  • Reduce swelling and irritation
  • Allow easier scale removal
  • Examples – triamcinolone, clobetasol propionate

Vitamin D Analogues

  • Slow down skin cell proliferation
  • Less strong than steroids
  • Example – calcipotriol

Coal Tar

Salicylic Acid

  • Facilitates shedding of excessive skin layers
  • Encourages medication absorption

Biologics

  • Injectable immunosuppressants
  • Used for moderate-severe cases unresponsive to other treatment

Using medicated shampoos containing vitamin D, steroids, or antimicrobial ingredients helps minimize scalp psoriasis between flare-ups.

Seborrheic Dermatitis Treatments

To manage seborrheic dermatitis long term, dermatologists endorse:

Antifungal Creams/Shampoos

  • Treat underlying yeast overgrowth
  • Common ingredients – ketoconazole, zinc pyrithione, ciclopirox

Low-Medium Potency Steroids

  • Counter inflammation
  • Example – hydrocortisone valerate foam/cream

Coal Tar Shampoos

  • Reduce scaling, itching, redness
  • Help normalize cell turnover

Calcineurin Inhibitors

-Specialized creams altering immune response

  • Example – pimecrolimus

Keratolytics

  • Loosen adherent scales
  • Contains salicylic acid or sulfur

Identifying and limiting triggers like skin irritants also helps minimize seborrheic dermatitis severity and frequency of flares.

Controlling Mild Dandruff

Most basic dandruff responds readily to a few adjustments:

More Frequent Shampooing

  • Removes emerging flakes
  • Clarifying shampoos deter yeast growth

Tea Tree Oil

  • Potent antimicrobial properties
  • Reduces fungus colonization

Zinc Pyrithione Shampoos

  • Fights yeast overgrowth
  • Normalizes cell turnover

Selenium Sulfide Shampoos

  • Curtail Malassezia yeast population
  • Examples – Selsun Blue, Head & Shoulders

As dandruff constitutes mild, intermittent seborrheic dermatitis, the above strategies also help counter early flares of seborrheic dermatitis itself.

Scalp Psoriasis or Seborrheic Dermatitis? – Key Diagnostic Questions

Distinguishing scalp psoriasis from seborrheic dermatitis holds importance for optimal treatment and outcomes. Dermatologists determining which one a patient has consider:

Are other body areas like knees, elbows affected?

Yes – supports psoriasis

No – more consistent with seborrheic dermatitis

Does it involve non-scalp regions like ears, face, chest?

Yes – favors seborrheic dermatitis

No – suggests psoriasis

How severe are the redness, pain and itching?

High severity – leans psoriasis

Mild – more likely seborrheic dermatitis

How well-defined are the lesion borders?

Clear distinct margins – psoriasis

Fuzzy borders – seborrheic dermatitis

How adherent are the scales?

Tightly stuck – psoriasis

Loosely attached – seborrheic dermatitis

Answers help guide appropriate courses of topical/systemic treatments to mitigate symptoms and minimize recurrences.

Seborrheic Dermatitis Treatment Considerations

Treating seborrheic dermatitis relies heavily on topical medications – shampoos, foams, gels or creams applied to affected areas. Factors influencing choice include:

Hair Texture

Coarse, coiled hair – cream or foams

Fine, straight hair – solutions or lighter foams

Severity

Mild – over-the-counter antifungal shampoo

Moderate – prescription selenium sulfide or ciclopirox

Severe – oral antifungal +/- steroid cream

Location

Scalp – medicated shampoo

Face – steroid cream/gel

Body – antifungal +/- tar preparation

Pregnancy/Breastfeeding

Topicals – safe first line

Systemics if unresponsive; not all are pregnancy-compatible

Determining optimal seborrheic dermatitis regimen relies on careful discussion between patient and provider accounting for these variables.

What Triggers Seborrheic Dermatitis Flares?

While seborrheic dermatitis’ exact cause remains uncertain, recognizable triggers provoke flare-ups. Identifying and limiting these factors helps maintain remission.

  • Stress

Heightens inflammation, upsets skin equilibrium

  • Weather Changes

Cold, dry air dehydrates skin escalating flares

  • Skin Irritants

Soaps, fragrances, alcohols disrupt skin barrier integrity

  • Medications

Lithium, beta blockers, immune suppressants incite flares

  • Hormonal Shifts

Menstrual cycles, postpartum state upset skin balance

  • Poor Nutrition

Deficiencies in zinc, vitamins A/E impair skin quality

  • HIV/Immune Dysfunction

Impaired immunity allows yeast overgrowth triggering outbreaks

While not all triggers can be controlled, minimizing effects of those possible helps reduce seborrheic dermatitis frequency and severity.

Children with Seborrheic Dermatitis vs Scalp Psoriasis

Infantile Seborrheic Dermatitis

Up to half of newborns develop “cradle cap” – crusty yellow-orange scalp scaling which may spread to eyebrows, ears and upper body. Cradle cap isn’t serious, resolves naturally and doesn’t require medicine.

Pediatric Psoriasis

Childhood psoriasis affects up to one third of those with psoriasis overall. Suspect childhood psoriasis if scalp flakes spread beyond hairline or if joints simultaneously become swollen. Consult pediatric dermatology to guide treatment.

FAQs: Scalp Psoriasis vs Seborrheic Dermatitis vs Dandruff

Does scalp psoriasis spread to other people?

No – scalp psoriasis isn’t contagious so head-to-head contact doesn’t transmit it like lice. Genetic susceptibility allows sporadic cases.

If I have seborrheic dermatitis, will my child get it too?

Possibly – genetics play a partial role in seborrheic dermatitis. Often when one parent has it, infants have higher likelihood of developing cradle cap.

How do I know if OTC dandruff shampoo isn’t working?

If a medicated dandruff shampoo hasn’t reduced scalp flaking after 4 weeks used twice weekly, consult a dermatologist to evaluate other causes like psoriasis, seborrheic dermatitis or fungal infection.

Does my baby’s cradle cap need steroids?

No – cradle cap is harmless, doesn’t bother most infants and resolves spontaneously around age 1 year. Try daily brushing and softening scales with mineral oil instead of using steroid creams without an exam.

When should I seek a dermatology referral?

See a dermatologist if you have scalp redness, significant flaking or hair shedding plus visible body rashes or nail changes which could indicate plaque psoriasis rather than run-of-the-mill seborrheic dermatitis or dandruff.

Key Takeaways

  • Scalp psoriasis stems from immune dysfunction causing excess skin turnover and thick white scale buildup plus hair loss
  • Seborrheic dermatitis relates to yeast overgrowth inducing milder yellow waxy scales, itching and flaking
  • Dandruff falls on the extremely mild end of seborrheic dermatitis with powdery flakes and minimal redness
  • Differentiating features help diagnose the condition to guide appropriate, effective therapy
  • Controlling triggers minimizes recurrence frequency and severity

While frustratingly similar in initial presentation, tailoring management to the specific diagnosis provides the best opportunity to successfully treat irritating scalp problems like psoriasis or seborrheic dermatitis. Accurate identification permits directing the most suitable topical and systemic therapies for symptomatic relief and maintenance of remission.

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