MASI (Melasma Area and Severity Index) (Echelle de MASI) (Pour les professionnels)

• This tool is mainly used in research for measuring severity in patients who have melasma (chloasma, pregnancy mask).
• It would be useful in the measurement of the melasma before and after a treatment for example.

• Its measurement relies on the measurement in 4 areas:
  • (F) forehead which accounts for 30% of the score
  • (RMR) right and (LMR) left malar region which each account for 30% of the score
  • (M) chin which accounts for 10% of the score

• The area (A) of melasma involvement is graded from 0 to 6:
  • 0 = no involvement
  • 1 = less than 10% involvement
  • 2 = 10% to 29% involvement
  • 3 = 30% to 49% involvement
  • 4 = 50% to 69% involvement
  • 5 = 70% to 89% involvement
  • 6 = 90% to 100% involvement

• The degree of pigmentation (P) and homogeneity (H) graded from 0 to 4:
  • 0 = absent
  • 1 = slight
  • 2 = mild
  • 3= marked
  • 4 = maximum

• MASI score =  0.3 A(F) [P(F) + H(F)] + 0.3 A(RMR) [P(RMR) + H(RMR)] + 0.3 A(LMR) [P(LMR) + H(LMR)] + 0.1 A(M) [P (M) + H (M)].

• This measurement is highly subjective and different values can be found in the same patient at the same time !
• It is subjective not only because each parameter is subjective but also because it is so complicated that physicians will calculate an approximate score based on impressions.
• It could be used clinically but for research a colorimeter would be a better option, especially if more precise and reproductible measurements are sought.

Contributors:

Dr Christophe HSU – dermatologist. Geneva, Switzerland
Source of Information: Alrawashdeh B. Melasma Update. Dubai World Dermatology & Laser Conference & Exhibition – Dubai Derma 13 – Dubai, United Arab Emirates (UAE)