Palmoplantar keratoderma (PPK) is made of a group of benign disorders that cause thickening of the palms and soles. It is generally divided into three categories: diffuse PPK, with involvement of the whole palmoplantar surface; focal and striate PPK, usually located mainly on pressure points; and punctate PPK, featuring multiple small hyperkeratotic papules, nodules, or spicules. This patient’s lesions are most consistent with punctate palmoplantar keratoderma (PPPK).
PPPK is usually inherited as an autosomal dominant trait, although acquired cases can be seen. It is also called Buschke-Fischer-Brauer syndrome, or keratodermia palmoplantaris papulosa. The condition affects men and women equally. Lesions usually appear during adolescence or after, unlike other forms of keratoderma, which may occur during childhood. While any race may be affected, in those of African descent, lesions are more common in the palmar creases. The condition is likely due to an aberration in proteins involved in keratin filament assembly. A mutation in the AAGAB gene can be at fault. PPPK can be associated with Darier’s disease and Cowden disease. Familial PPPK may be associated with Hodgkin disease, squamous cell carcinoma, kidney, breast, colon, and pancreatic cancer.
Upon physical exam, multiple keratotic, punctate papules are present on the palms and soles, which may appear clear or more opaque. They may also have a verrucous appearance. Some lesions may have a central keratotic core and appear more comedonal. Most often, lesions are nontransgradient, meaning they only involve the palms and soles. Sometimes lesions may extend to the top of the hands and feet as well, which is called transgradient. Lesions are typically asymptomatic, although larger lesions can become painful with friction. Other types of PPPKs include filiform keratoderma and marginal keratoderma.
Histologic evaluation reveals columns of hyperkeratosis with an increased granular layer. There is no dermal inflammation. Clinically, the differential diagnosis is limited. Verruca vulgaris will reveal bleeding points upon paring with a blade. In spiny keratoderma, also called punctate porokeratosis of the palms and soles, lesions protrude more and resemble “music box spines.” Histologically, columnar parakeratosis is seen. Pitted keratolysis have reduced stratum corneum and a distinct clinical appearance.
If treatment is desired, emollients, keratolytics such as topical retinoids, salicylic acid, lactic acid, and urea may be used. Oral retinoids may be useful in symptomatic patients. Surgery and CO 2 laser may be an option for resistant lesions.
This case and photos were submitted by Dr. Bilu Martin.
Dr. Bilu Martin is a board-certified dermatologist in private practice at Premier Dermatology, MD, in Aventura, Fla. More diagnostic cases are available at edermatologynews.com. To submit a case for possible publication, send an email to firstname.lastname@example.org.