Palmoplantar Keratodermas

(1)

Hôpital Universitaire de Strasbourg, Strasbourg, France

Abstract

Palmoplantar keratodermas are a common clinical finding and thus addressed in this chapter. Keratoderma is a scaly and/or keratotic thickening of the palms and/or soles. Keratoderma may affect exclusively the palms, or the soles, or both. The diagnosis of the underlying causative disorder can be difficult, as differential diagnosis includes many different diseases. The acquired forms are more common and may reveal a serious disease such as cancer or lymphoma. They may also be triggered by an infection such as reactive arthritis (i.e., keratoderma blennorrhagica). Frequent causes of keratodermas are dermatophytosis, orthoergic dermatitis, or psoriasis. However, they have many potential causes and they can be one of the signs or early in the course the only sign of a general disease, such as dermatomyositis or hypothyroidism. They also correspond to the acral manifestation of many dermatoses, such as ichthyoses.

Keratoderma can be localized or diffuse. When diffuse, they affect the entire palm and sole. The localized forms can be focal, striated, or punctate. Hence they produce round, keratotic areas of a few millimeters wide. These keratotic areas are described as focal when measuring more than 5–10 mm and punctate when millimeter wide.

They are described as striated when producing linear or reticulated areas and transgredient (“keratoderma transgrediens”), when extending over the palmar and/or plantar area and when the keratosis thus spreads towards the lateral or dorsal parts of hands or feet.

The diagnosis of the numerous variants of congenital keratodermas is based on heredity (AD, AR, or X-linked, mitochondrial, etc.), semiology (diffuse or localized, focal, striated, or punctate), and associated signs (isolated or syndromic). The association of early keratoderma with wooly hair is often the first expression of a hereditary disease of desmosomes, which exposes to a potentially lethal cardiac risk (arrhythmogenic right ventricular cardiomyopathy, left ventricular dilated cardiomyopathy) in patients with Naxos or Carvajal syndromes.

Box 38.1

Main Causes of Acquired Keratodermas and Keratodermas Occurring in Well-Defined Diseases

Mecanogenic causes

Infectious causes

Crusted scabies

Mycoses (dermatophytosis)

Pitted keratolysis caused by Corynebacterium minutissimum

Reactive arthritis

Secondary syphilis and endemic treponematosis (pian)

Verrucous tuberculosis

Warts

Drug-related causes (gold salts, hydantoin, mepacrine, proguanil, mexiletine, alpha-methyldopa, practolol, hydroxyurea, retinoids, streptomycin)