الفهرس 
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Abstract
Melasma is a symmetric progressive skin hyperpigmentation occurring in all population but with great predilection in darker skin photo-types. Pathogenesis of melasma is not yet clear, but some factors may play a role like: prolonged sun exposure, pregnancy, hormonal therapies and genetic background.
Truly effective treatment of melasma is still a challenge and is quite elusive. These treatment approaches include; topical agents, chemical peels, lasers and light-based devices.
In our study we used oral TXA drug with dosage 250 mg twice daily for 4 months on 15 cases to evaluate the clinical, histopathological (H&E, FM and Giemsa stains) and immunohistochemical (anti-tyr ab, VEGF) changes at the end of treatment compared to baseline.
According to the type of melasma, different assessment methods were concordant in 80% of cases.
Our study had demonstrated that there was clinical improvement after treatment with significant reduction in MASI score compared to baseline. After follow up period we noticed a recurrence in (26.7%) of cases with variable degrees. There were no serious side effects noticed in our study except for few reversible temporary ones.
As regard histiopathological changes of treated patients, H&E and FM stained sections showed remarkable reduction of the melanin density in basal layer as well as decreased density of melanophages in dermis compared to baseline. Giemsa stained sections showed a noticeable reduction in the number of mast cells.
Regarding immunohistochemistry, we observed a down regulation of both Anti-tyr ab and VEGF post‐treatment compared to baseline.
The present study suggested the inhibitory action of TXA on melanin synthesis, decreased pigmentary incontinence, decreased tyrosinase activity & vascularity, reduction in the number of mast cells and suggesting that TXA has an anti‐inflammatory action as well.
In conclusion, on the basis of the previously reported findings, oral TXA in a low dose of 250 mg twice daily can be used as an effective, safe and promising therapeutic agent for treatment of melasma. Oral TXA is easily available and affordable with no serious side effects. However, patients should be screened carefully for contraindications and risk factors before starting treatment to avoid serious side effects and they should be counseled about the risks associated with therapy. One of limitations of our study that it is a non-controlled study; also it was conducted on small sample size. Future research should evaluate the lowest effective dose and the adequate duration of treatment as well as the maintenance needed for long-term control based on a larger sample size.