Punctate palmoplantar keratoderma (punctate PPK), or keratosis punctata, is a heterogeneous group of conditions characterized by small hyperkeratotic growths on the palms and soles. Many cases are inherited in an autosomal dominant fashion, although sporadic cases have also been reported. There is no sex predilection.

Numerous subtypes have been identified, and varied classification systems exist:

Punctate PPK type 1, also known as the diffuse type, Buschke-Fischer-Brauer disease, keratosis punctata palmaris et plantaris, and keratosis papulosa – Patients present with small hyperkeratotic papules on the palms or soles that appear in late childhood to adolescence. These lesions increase in size and number with time. Mutations in the alpha and gamma adaptin binding protein (AAGAB) on chromosome 15 have been identified. Only a few reported kindreds have associated malignancy (squamous cell carcinoma, Hodgkin disease, and renal, breast, lung, prostatic, pancreatic, and colonic adenocarcinomas). Other rare associations include spastic paralysis, ankylosing spondylitis, anodontia, deuteranopia, deuteranomaly, freckle-like hyperpigmentation, or HIV disease.

Punctate PPK type 2, also known as spiny keratoderma and music box spine keratoderma – In the inherited form, patients present with tiny keratotic spines on the palms and soles that appear in childhood. Sporadic cases present later in life and may be associated with renal, pulmonary, and gastrointestinal carcinomas, as well as lymphoproliferative malignancies and melanoma. Other reported underlying disease associations have included polycystic kidney disease, chronic renal failure, type 4 hyperlipoproteinemia, and pulmonary tuberculosis.

Punctate PPK type 3, also known as acrokeratoelastoidosis (AKE), marginal keratoderma, acrokeratoelastoidosis lichenoides, focal acral hyperkeratosis (FAH), and acrokeratoelastoidosis of Costa – Patients present with flat or umbilicated keratotic shiny papules on the marginal border of the palms, soles, and digits that erupt during adolescence or young adulthood. Hyperhidrosis may occur in some patients.

FAH appears during young adulthood and is clinically identical to AKE. The major difference between these 2 disorders is the histopathologic finding of elastorrhexis (fragmentation and degeneration of elastic fibers) in the dermis, a feature that is present in AKE but absent in FAH. In addition, hyperhidrosis is rarely associated with AKE but is not associated with FAH. It is still controversial whether FAH is a distinct entity or a variant of AKE.

Punctate PPK of the palmar creases (keratosis punctata of the palmar creases) is a distinct variant that has been identified in patients of African descent.

In Cole disease, punctate PPK is seen in association with guttate hypopigmentation, with or without calcifications within tendons, skin, and breast tissue.

Related topic: palmoplantar keratoderma