Palmoplantar keratoderma, aka Keratosis Palmaris et Plantaris, is a not really as much a diagnosis as it is a symptom of another underlying condition. It is, as you see, characterized by a thickening of the palms and soles which may be diffuse or, as above, not. It can also be punctate, but in my mind that condition doesn't really fit with the others.
It may be associated with underlying malignancy, resulting sometimes in bizarre patterns such as tripe palms; it may be associated with ectodermal dysplasias, or the straightforward genetic maladies which are too numerous to count in this forum.
In an acquired setting, it can be associated with menopause, meds, infections and systemic disease.