Drug-Induced Pigmentary Changes

Intro & Mechanisms - Hue Done It?

• Alteration in skin or mucous membrane coloration caused by systemic or topical medications.
• Key Mechanisms:
  • ↑ Melanin production: e.g., ACTH, psoralens, heavy metals (gold, silver).
  • Drug/metabolite deposition in dermis:
    • Amiodarone (slate-gray).
    • Minocycline (blue-gray, often in scars).
    • Antimalarials (blue-black; shins, palate).
    • Clofazimine (reddish-brown).
  • Drug-induced Post-Inflammatory Hyperpigmentation (PIH).
  • Hemosiderin deposition (e.g., after drug-induced purpura).

⭐ Drug-induced pigmentary changes are often reversible upon discontinuation of the offending agent, but resolution can be slow.

Drugs & Patterns - The Color Code

• Drug-induced pigmentary changes are common, resulting from various mechanisms: ↑ melanin synthesis (e.g., ACTH, OCPs), deposition of the drug or its metabolites (e.g., amiodarone, minocycline, heavy metals), or post-inflammatory hyperpigmentation (e.g., FDE).

Star Offenders - Pigment Parade

• Amiodarone: Slate-grey/blue-violet, photosensitive pigmentation. 📌 "Ami-Blue-Darone". Sites: Face, hands. Dose >200mg/day.
• Minocycline: Blue-black/grey pigmentation. Sites: Scars (Type I), shins (Type II), diffuse sun-exposed (Type III), sclera, teeth.

  ⭐ Minocycline can cause blue-black pigmentation in scars, shins, and sclera, often dose-dependent and related to iron chelation.

• Antimalarials (Chloroquine, Hydroxychloroquine): Yellow-brown to blue-grey. Sites: Shins (pretibial), face, palate, nails. Retinal risk.
• Zidovudine (AZT): Brown hyperpigmentation. Sites: Nails (longitudinal melanonychia), oral mucosa.
• Phenothiazines (e.g., Chlorpromazine): Slate-grey/purplish-brown. Sites: Sun-exposed areas. High doses, long term.
• Clofazimine: Reddish-brown to violaceous discoloration. Sites: Leprosy lesions, skin, conjunctiva, bodily fluids (sweat, urine). Dose-dependent.
• Heavy Metals:
  • Gold (Chrysiasis): Blue-grey, sun-exposed areas.
  • Silver (Argyria): Diffuse slate-grey/blue, generalized.
• Cytotoxic Agents:
  • Bleomycin: Flagellate (whip-like) hyperpigmentation, linear streaks.
  • Busulfan: Diffuse "Busulfan tan".
  • 5-Fluorouracil (5-FU): Photosensitive areas, serpentine supravenous hyperpigmentation.

Dx & Rx - Fading Shades

• Diagnosis:
  • Key: Detailed drug history, temporal link to onset.
  • Clinical exam: Note specific pattern, color (e.g., blue-grey, brown).
  • Skin biopsy: If diagnosis unclear; reveals melanin or drug deposits.

  ⭐ Wood's lamp examination can help differentiate epidermal (enhances) from dermal (no enhancement) pigmentation, guiding diagnostic and therapeutic approaches.

• Management:
  • Primary: Discontinue causative drug immediately.
  • Sun protection: Broad-spectrum sunscreen vital.
  • Topical agents: Hydroquinone, azelaic acid, retinoids.
  • Lasers: Q-switched (Nd:YAG, Ruby) for refractory pigmentation.
  • Counseling: Reassure; fading is gradual (months to years).

High‑Yield Points - ⚡ Biggest Takeaways

• Amiodarone: Causes slate-grey/bluish pigmentation, mainly in sun-exposed skin.
• Minocycline: Induces blue-grey pigmentation in scars, sclera, and teeth.
• Antimalarials (Chloroquine): May cause blue-black patches on shins, face, palate.
• Phenothiazines: Result in slate-grey/purplish hues in photodistributed areas (chronic use).
• Zidovudine (AZT): Causes nail pigmentation (longitudinal melanonychia) and macular hyperpigmentation.
• Fixed Drug Eruption (FDE): Recurrent violaceous plaques leaving persistent hyperpigmentation.
• Bleomycin: Cytotoxic drug causing distinctive flagellate (whip-like) hyperpigmentation.