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melasma (chloasma, mask of pregnancy)

From the Greek 'a black spot'. An acquired light or dark brown hyperpigmentation in a sun-exposed area, most frequently on the face. Etiology: 1) sun exposure 2) pregnancy* 3) contraceptive hormones* 4) medications - dilantin 5) idiopathic * estrogent may play a role Epidemiology: 1) common 2) more common in Asian, Middle Eastern, Indian, South American individuals 3) 90% females, most premenopausal 4) more frequent in sunny areas Pathology: 1) increase in production & transfer of melanosomes to keratinocytes 2) possible increase in number of melanocytes 3) may be dermal, epidermal or mixed Genetics: 30% of patients have family history of melasma [2] Clinical manifestations: 1) patchy macular hyperpigmentation evolving over weeks - generally symmetric hyperpigmentation on sun-exposed skin - generally on face - hyperpigmentation may begin on cheeks, then spread around eyes & onto forehead 2) light or dark brown, blue-gray or black - dermal melasma (nevus of Ota) is blue-gray, similar to tattoo Differential diagnosis: - post-inflammatory hyperpigmentation - lentigines: macular lesions generally smalled than those of melasma - nevus of Ota: - blue-gray hyperpigmentation because pigment is dermal vs epidermal Management: 1) strictly a cosmetic problem 2) only epidermal melasma is responsive to therapy [2] 3) hydroquinone 12% topical (Musely) advertised as effective treatment [6] 4) combination therapy more effective than monotherapy [2] 5) 3% hydroquinone in combination with topical tretinoin 6) azelaic acid or kojic acid 7) prevention a) mainstay of treatment is sun protection - use of sunscreen & sun-protective clothing recommended [4] b) opaque sunblock - titanium dioxide or zinc oxide c) SPF 30 ineffective

Related

hyperpigmentation

General

skin disease (dermatologic disorder, dermatopathy, dermatosis) granuloma

References

  1. Color Atlas & Synopsis of Clinical Dermatology, Common & Serious Diseases, 3rd ed, Fitzpatrick et al, McGraw Hill, NY, 1997, pg 300-301
  2. Goodheart HP & Mamis S Skin disorders in women of color Disorders of pigmentation - melasma Women's Health in Primary Care 8:473, 2005
  3. Sheth VM, Pandya AG. Melasma: a comprehensive update: part I. J Am Acad Dermatol. 2011 Oct;65(4):689-697. Review. PMID: 21920241
  4. Medical Knowledge Self Assessment Program (MKSAP) 19 American College of Physicians, Philadelphia 2022
  5. Ogbechie-Godec OA, Elbuluk N. Melasma: an up-to-date comprehensive review. Dermatol Ther (Heidelb). 2017;7:305-18. PMID: 28726212
  6. Musely Works. The Spot cream. https://www.musely.com/spotcream
  7. Passeron T. Melasma pathogenesis and influencing factors - an overview of the latest research. J Eur Acad Dermatol Venereol. 2013 Jan;27 Suppl 1:5-6. PMID: 23205539 Review.