The disfiguring condition is best known as the disease that plagued late pop star Michael Jackson.
Vitiligo is a common, psychologically devastating condition that causes skin to lose its pigmentation or colour.
Current treatments, such as steroid creams and light therapy, are not reliably effective in reversing the disease.
Recent advances in vitiligo research led investigators from the Yale School of Medicine in US to consider an existing class of Food and Drug Administration (FDA) approved medications known as Janus kinase (JAK) inhibitors, as a possible treatment.
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King and co-author Dr Brittany Craiglow, believed the same medicine might be effective for vitiligo.
To test the hypothesis, King and Craiglow administered tofacitinib to a 53-year-old patient with prominent white spots covering her face, hands, and body.
For more than a year prior to taking tofacitinib, the numbers of these white spots had been increasing.
Within two months of treatment, the patient experienced partial repigmentation on her face, arms, and hands - the areas that concerned her most.
The results could represent a breakthrough in vitiligo treatment, researchers said.
"While it's one case, we anticipated the successful treatment of this patient based on our current understanding of the disease and how the drug works," said King.
King said further research would be necessary to confirm the drug's safety and efficacy and cited work by University of Massachusetts Medical Center dermatologist and scientist John Harris as the inspiration for trying tofacitinib in this patient.
"This may be a huge step forward in the treatment of patients with this condition," King added.
King hopes to conduct a clinical trial using tofacitinib, or a similar medicine, ruxolitinib, for the treatment of vitiligo.
The finding was published in the journal JAMA Dermatology.