There can be a number of causes for this condition. To arrive at the most probable cause, one would have to know what the underlying skin looks like and if this is a general condition all over the foot or if it is localized to specific areas of the foot. Is the underlying skin red and inflamed or is it pink and normal in appearance? Are the thick areas of skin only under weight-bearing areas which would indicate a mechanical (friction or pressure) cause? Contact with a skin irritant such as detergents or chemicals used in washing clothing or the manufacture of shoes may be the cause. Certain systemic diseases such as psoriasis, atopic eczema, and scleroderma can also cause generalized thickening of the skin of the feet.
The peeling skin may be the tipoff to the most probable cause in this case: a fungal infection of the skin caused by the tinea rubrum species of fungus. The underlying and around the edges of the thickened areas are usually red and inflamed. Small cracks may appear in the skin, and in general, the foot does not look healthy. This fungal condition is quite resistant to treatment, but with proper medication can be cured. – Godfrey Mix, D.P.M.
These symptoms can be caused by many different dermatologic conditions. Tinea pedis (athlete's foot), psoriasis, eczema, xerosis, and many other problems can contribute to thick, peeling skin. Your client could try a heavy emollient with glycolic acid or Lac Hydrin 5% twice daily for several weeks. If that does not help the problem, a dermatologist or podiatrist should be consulted. – Phoebe Rich, M.D.