When I visited her months later, the callosity not only remained, but had grown. Since I lived in Washington, DC, and worked for an international organization, I contacted reputed dermatologists, who recommended a panoply of various medicines. I bought them and send them to her, insisting she use them.
My brother, a psychologist who had been in medical school, examined the finger a year later and found no improvement. He wrote to his professional friends worldwide, gathered latest data and prescribed some more medicine. No result either.
When my mother returned home after two days, the patch was gone. A fifteen year old rural girl who could not read had found a solution that had tenaciously eluded top medical specialists in three continents.