Post-inflammatory Hypopigmentation

Post-inflammatory Hypopigmentation

Post-inflammatory Hypopigmentation

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PIH: Intro & Pathophys - Fading Fast

  • Acquired disorder: ↓ or absent skin pigment post-inflammation or injury.
  • More frequent and visually prominent in individuals with darker skin tones (Fitzpatrick types III-VI).
  • Usually temporary, but resolution can be slow (months to years).
  • Pathophysiology involves:
    • ↓ Melanin synthesis within melanocytes.
    • Impaired transfer of melanosomes to surrounding keratinocytes.
    • Actual loss or destruction of melanocytes in severe cases.
  • Inflammatory mediators (e.g., certain cytokines, leukotrienes) are key culprits.

⭐ PIH often follows conditions like eczema, psoriasis, acne, burns, or even cosmetic procedures, especially in pigmented skin types.

PIH: Etiology & Clinical - Spot the Lesions

  • Etiology (Common Triggers):
    • Inflammatory dermatoses: Eczema, Psoriasis, Lichen planus.
    • Infections: Pityriasis versicolor, Herpes zoster.
    • Physical injury: Burns, Cryotherapy, Laser, Chemical peels.
    • Medications: Topical steroids (prolonged).
  • Clinical Presentation (Lesions):
    • Appearance: Hypopigmented macules/patches, not completely depigmented.
    • Color: Lighter than skin; varies from subtle loss to pallor.
    • Borders: Indistinct, "smudged," follows prior inflammation pattern.
    • Distribution: Localized to sites of previous inflammation or injury.
    • Symptoms: Usually asymptomatic; may have pruritus from prior cause.

⭐ On Wood's lamp, PIH shows some retained pigment (incomplete loss), unlike vitiligo's stark, chalky-white fluorescence.

PIH: Diagnosis & DDx - The Right White

  • Diagnosis:

    • Key: History of prior inflammation (e.g., eczema, psoriasis, acne, burn).
    • Lesions: Hypopigmented (not achromic/depigmented); borders often ill-defined.
    • Wood's Lamp: May accentuate hypopigmentation; no bright blue-white fluorescence (unlike vitiligo).
    • Biopsy (rarely needed): ↓ melanin in epidermis; melanocyte count usually normal. Post-inflammatory hypopigmentation
  • Key DDx - Distinguishing Features:

    • Vitiligo: Complete depigmentation (achromia); well-demarcated; chalky-white fluorescence on Wood's lamp.

      ⭐ PIH typically shows normal melanocyte numbers with reduced melanin production/transfer, while vitiligo often demonstrates a complete absence of melanocytes.

    • Pityriasis Alba: Ill-defined, fine scales, faint erythema; common in atopic individuals, face/extensors.
    • Tinea Versicolor: Multiple, well-demarcated, scaly macules; KOH positive ("spaghetti & meatballs"); variable Wood's lamp fluorescence (e.g., yellowish-green).
    • Idiopathic Guttate Hypomelanosis (IGH): Small (2-5mm), discrete, "porcelain-white" macules; sun-exposed limbs.

PIH: Management & Prognosis - Restore the Hue

  • Primary Goal: Treat underlying dermatosis; reassure patient (often self-limiting).
  • Sun Protection: Essential daily; broad-spectrum sunscreen helps ↓contrast with normal skin.
  • Topical Therapies:
    • Mild corticosteroids (e.g., hydrocortisone 1%): Short-term for any residual inflammation.
    • Topical Calcineurin Inhibitors (TCIs): Pimecrolimus, tacrolimus (preferred for face, flexures).
  • Phototherapy (Persistent/Widespread PIH):
    • Excimer laser (308 nm): Targeted therapy for localized, stable lesions.
    • Narrowband UVB (NB-UVB): Option for more extensive PIH.
  • Cosmetic Camouflage: Medicated or commercial concealers (e.g., Dermablend).
  • Prognosis:
    • Generally good; spontaneous repigmentation common over months to years.
    • Slower if significant dermo-epidermal junction damage or delayed treatment of primary cause.

    ⭐ Repigmentation typically initiates perifollicularly (around hair follicles) or from the lesion's periphery, gradually coalescing centrally.

High‑Yield Points - ⚡ Biggest Takeaways

  • Acquired loss of pigmentation following cutaneous inflammation or injury.
  • Caused by impaired melanocyte function or reduced melanocyte numbers, leading to decreased melanin.
  • Clinically appears as ill-defined macules or patches lighter than normal skin.
  • Distribution typically follows the pattern of the original dermatosis.
  • Diagnosis is usually clinical, relying on patient history and lesion appearance.
  • Generally self-limiting, with spontaneous repigmentation occurring over months to years.
  • Strict sun protection is vital to minimize contrast and support repigmentation.

Practice Questions: Post-inflammatory Hypopigmentation

Test your understanding with these related questions

Match the following woods lamp findings: 1. Erythrasma, 2. Pityriasis versicolor, 3. Tinea capitis, 4. Vitiligo || a. Yellow b. Coral red fluorescence c. Pink d. Green e. Milky white

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Flashcards: Post-inflammatory Hypopigmentation

1/10

_____ is the hypopigmentation seen in secondary syphilis after the copper-red rash fades away

TAP TO REVEAL ANSWER

_____ is the hypopigmentation seen in secondary syphilis after the copper-red rash fades away

Leukoderma syphiliticum

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