What could cause dry skin on the palm of one's hands?

One idea ... . I've learned i can't second-guess rashes without seeing them in person, but read about dishydrotic eczema / pompholyx and see whether you might not have this. Just my thought.
Dyshidrosis. Read this article http://www.Livestrong.Com/article/77051-dry-skin-hands-feet/ which summarizes the common causes of dry skin on the hands (and feet), treatments, and other important information. Dry skin is usually a temporary condition, and moisturizers can be helpful, as well as identifying the root causes and taking steps to minimize exposure.