The Sole of My Foot Is Abnormally Thick!

Have you noticed that the sole of your foot is abnormally thick and almost looks like reptile scales? What you likely have is one of a variety of palmoplantar keratodermas, a heterogeneous group of disorders characterized by an abnormal thickening of skin on either the palms or soles of the feet.

There are three types of patterns of palmoplantar keratodermas, which include:

*Diffuse

• Diffuse palmoplantar keratoderma is characterized by thick, even, and symmetric hyperkeratosis over the whole of the sole. They are present at birth or during the first few months of life. 
• Diffuse epidermolytic palmoplantar keratoderma is one of the most common patterns of this condition. This too is evident at birth and is characterized by demarcated symmetric thickening of the soles, with a "dirty" snakeskin appearance.
• Diffuse nonepidermolytic palmoplantar keratoderma is an inherited autosomal dominant condition, present at birth, and is characterized by well-demarcated, symmetric keratoses, and a "waxy" appearance.

*Focal

• Focal palmoplantar keratoderma is characterized by large, compact masses of keratin which develop at sites with recurrent friction. The pattern of calluses may be discoid or linear.
• Focal palmoplantar keratoderma with oral mucosal hyperkeratosis is an autosomal dominant keratoderma that represents an overlap with pachyonychia congenita type 1 without the typical nail involvement. 

*Punctate

• Punctate palmoplantar keratoderma is characterized by tiny "raindrop" keratoses which involve the palmoplantar surface, but may be restricted in their distribution.

*Ungrouped

• Palmoplantar keratoderma and spastic paraplegia is an autosomal dominant or x-linked dominant condition that begins in early childhood with thick keratoderma over the soles.
• Palmoplantar keratoderma of Sybert is characterized by a glove-and-stocking distribution with severe symmetric involvement of the whole surface and is extremely rare. 
• Striate palmoplantar keratoderma involves the soles at birth or during the first few years of life.