Unilateral Linear Punctate Palmoplantar Keratoderma: A Case Report

Abstract

Punctate palmoplantar keratoderma (PPPK) is a rare entity with an estimated prevalence rate of 1.17/100,000. PPPK usually presents with bilateral asymptomatic, tiny, hyperkeratotic punctate papules and plaques on the palmoplantar surface. Among the PPPK varieties, the linear presentation is much rarer, and so far there have been only 3 case reports. Here, we report the case of a 27-year-old female Thai patient who presented to our outpatient clinic with unilateral asymptomatic linear thickening lesions on her right sole since childhood. There were no similar lesions on other parts of the body. A histopathologic examination revealed epidermal hyperplasia and hyperkeratosis without columns of parakeratosis or cornoid lamella. The other examinations were normal. The clinical and histological contexts were consistent with a diagnosis of unilateral linear PPPK. The patient was treated with topical 10% urea cream and 10% salicylic acid cream twice daily. To the best of our knowledge, this is the first reported case of unilateral linear PPPK in Thailand, and the fourth reported case worldwide.

Case of punctate palmoplantar keratoderma type I treated with combination of low‐dose oral acitretin and topical salicylic acid and steroid

“…PPK can be classified according to whether they are inherited or acquired. Hereditary PPK can be clinically categorized into three subgroups: diffuse PPK, focal PPK and PPPK . These diseases can be distinguished on the basis of mode of inheritance, the site of invasion, accompanying symptoms and extent of epidermal involvement .…”

“…It is believed that both genetic and environmental factors play some roles in triggering the disease. The PPPK tends to be inherited autosomal dominantly and has been known to be linked with two loci on chromosomes 15q22–15q24 and 8q24.13–8q24.21 . Recently, the pathogenic mutations in the AAGAB gene on 15q were identified, which encodes the α‐ and γ‐adaptin‐binding protein p34 .…”

“…Topical keratolytics (urea, salicylic acid, lactic acid) are helpful for symptomatic control. Liquid nitrogen and psoralen plus ultraviolet A therapy have been tried with variable success . Traditional systemic retinoids have been used for treatment of PPPK by regulating keratinocyte differentiation .…”

“…Palmoplantar keratodermas (PPK) are heterogeneous disorders characterized by abnormal keratinization . PPK can be classified according to whether they are inherited or acquired . Punctate PPK (PPPK), one of the subtypes of hereditary PPK, is a rare punctate keratoderma characterized by tiny “raindrop” keratoses having a tendency to coalesce on the edge of soles, which are exposed to sustained pressure .…”

“…The exact etiology of PPPK has not been fully understood. It is believed that both genetic and environmental factors play some roles in triggering the disease . It has been known to be linked to genetic mutations leading to a hyperproliferation hyperkeratosis on the epidermis .…”