Melasma

Melasma is a benign skin condition characterized by hyperpigmentation of sun-exposed regions due to excess melanin production and deposition. The condition mainly affects women during their reproductive years, particularly those with darker skin tones. Hyperpigmented patches typically occur on the face, especially the cheeks, chin, forehead, and upper lip. The diagnosis is clinical. Management includes sun protection and topical depigmenting agents.

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Overview

Definition

Melasma, also known as chloasma, is a benign condition of the skin characterized by hyperpigmentation in sun-exposed areas.

Epidemiology

  • Prevalence varies greatly: 1.5%–15.5%
  • Sex: 9 times more common in women than men
  • Age:
    • Rare before puberty
    • More common in reproductive years
  • Race:
    • Higher prevalence in individuals with darker skin tones
    • More common in Hispanics and Asians

Etiology

  • Sunlight/ultraviolet (UV) radiation exposure
  • Hormonal factors: 
    • Pregnancy (melasma is often called the “mask of pregnancy”)
    • Use of oral contraceptive pills (OCPs)
    • Hormone replacement therapy (HRT)
  • Photosensitizing medications
  • Genetic predisposition
  • Strong association with thyroid disorders

Pathophysiology

Hyperactive melanocytes deposit excess melanin in the epidermis and dermis of the skin.

Clinical Presentation and Diagnosis

Clinical presentation

Patients develop hyperpigmented lesions.

  • Occurs on any sun-exposed area of the body, most commonly: 
    • Cheeks
    • Chin
    • Forehead
    • Upper lip
  • Appearance:
    • Tan or brown
    • Well demarcated
    • Splotchy (irregular)
    • Symmetric
    • Macules or patches 

Diagnosis

The diagnosis of melasma is clinical.

Management and Prognosis

Management

  • General management:
    • Minimize sun exposure.
    • Sunscreen
    • Consider discontinuation of or alternatives to HRT and OCPs.
    • Patients should be screened for thyroid disease.
  • Topical depigmenting agents are the 1st-line treatment:
    • Hydroquinone cream
    • Azelaic acid
    • Topical retinoids (tretinoin)
  • Chemical peels or laser therapy are 2nd-line options if topical management fails.

Prognosis

  • Melasma associated with pregnancy often spontaneously fades within a year of delivery.
  • Recurrence is common with sun exposure, no matter what the initial inciting event.

Differential Diagnosis

  • Hori’s nevus: hyperpigmentation condition commonly seen in Asian populations, particularly in Chinese and Japanese women of reproductive age. Hori’s nevus is an acquired condition that often presents as bilateral, speckled, blue-gray to gray-brown macules on the cheeks, but may also affect other parts of the face. The diagnosis is clinical. Management is typically with laser therapy and chemical peels.
  • Riehl melanosis: also known as pigmented contact dermatitis, a skin condition caused by cosmetic ingredients. Presents with onset of erythema and pruritus, followed by a diffuse, reticulated hyperpigmentation of the skin. The face and neck are often involved. The diagnosis is clinical, but patch testing can be done to identify the offending agent. Management includes avoiding the offending agent, skin-protective measures, and skin-lightening treatments.
  • Discoid lupus erythematosus: most common form of cutaneous lupus. The condition presents with circular, red or purplish scaly plaques, and most commonly occurs on the head and neck. Hyperpigmented lesions can be interspersed with areas of scarring and hypopigmentation. Lesions are also photosensitive. The diagnosis is made with identification of autoantibodies. Steroids and anti-malarial medications are used for management.
  • Solar lentigo: hyperpigmentation condition caused by chronic and excessive sun exposure. Presents as tan or dark-brown macules in sun-exposed areas of skin. The diagnosis is clinical, but biopsy may be performed to rule out skin cancer. Management is with cryotherapy or lasers.
  • Phototoxic dermatitis: a skin reaction secondary to the use of a systemic or topical phototoxic medication that causes increased sensitivity of the skin to UV radiation. Patients present similar to a severe sunburn with erythema in sun-exposed regions. Vesicles and blisters may also develop. The diagnosis is usually clinical. Management can include avoidance of sun exposure and phototoxic agents, topical or systemic corticosteroids, and cold compresses.

References

  1. Lehrer, M. (2018). Melasma. Retrieved March 4, 2021, from https://medlineplus.gov/ency/article/000836.htm
  2. Grimes, P.E. (2019). Melasma: Epidemiology, pathogenesis, clinical presentation, and diagnosis. UpToDate. Retrieved March 4, 2021, from https://www.uptodate.com/contents/melasma-epidemiology-pathogenesis-clinical-presentation-and-diagnosis
  3. Vashi, N., Kundu, R. (2019). Acquired hyperpigmentation disorders. UpToDate. Retrieved March 4, 2021, from https://www.uptodate.com/contents/acquired-hyperpigmentation-disorders
  4. Grimes, P. E., Callender, V. D. (2021). Melasma: Management. UpToDate. Retrieved March 4, 2021, from https://www.uptodate.com/contents/melasma-management
  5. Das, S. (2020). Hyperpigmentation. MSD Manual Professional Version. Retrieved March 10, 2021, from https://www.msdmanuals.com/professional/dermatologic-disorders/pigmentation-disorders/hyperpigmentation
  6. Basit, H., Godse, K.V., and Al Aboud, A.M. (2021). Melasma. StatPearls. Retrieved March 10, 2021, from https://www.ncbi.nlm.nih.gov/books/NBK459271/
  7. Lyford, W.H. (2020). Melasma. In James, W.D. (Ed.). Medscape. Retrieved March 10, 2021, from https://emedicine.medscape.com/article/1068640-overview

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