Diagnosis: Palmoplantar keratoderma

Our patients had familial diffuse palmoplantar keratoderma (PPK). Various synonyms of PPK include keratosis palmaris et plantaris, Unna-Thost disease, tylosis palmaris et plantaris, ichthyosis palmaris et plantaris, and symmetric hereditary keratoderma palmare et plantare.

There are three distinct types of PPK: Diffuse PPK features uniform involvement of the palmoplantar surface; focal PPK presents with localized areas of hyperkeratosis on pressure points; and punctate PPK demonstrates keratotic papules, similar to tiny corns, on the palms and soles. Defects in the epidermal keratin composition associated with base mutations in genetic markers may aid future classification.

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Diffuse PPK can present without any systemic sequelae, or it can manifest with numerous anatomic deformities. In Papillon-Lefèvre syndrome, PPK is accompanied by atrophy of the alveolar bone, hemorrhagic gingivitis, and fetor oris. Patients are usually edentulous by age 15. Esophageal carcinomas and calcifications of the cerebral sulci can also occur. Another manifestation of PPK is mal de Meleda. 

Diffuse PPK usually appears in the third or fourth month of life as red skin on the palms and soles, followed by thick, yellow hyperkeratosis, the surface of which is usually smooth and waxy but can be irregular and verrucous. Lesions are sharply demarcated with an erythematous border at the wrists; extensor surfaces usually are not involved. Occasionally, nails and other frictional body surfaces, such as elbows and knees, are included in the keratotic process. Hyperhidrosis, secondary dermatophyte infections, and pitted keratolysis are often present. By age 3, PPK manifests completely.

Histologically, the epidermis demonstrates hypertrophy of all layers, especially the stratum corneum. Tonofilaments are clumped, resulting in perinuclear vacuolization. Large keratohyalin granules are seen in the spinous and granular cell layers. The eccrine glands may exhibit hypertrophy.

PPK is resistant to most therapy, although keratolytics, such as salicylic acid, topical vitamin A preparations, steroid creams, topical urea, 50% propylene glycol in water under plastic occlusion, and lactic acid creams, are sometimes helpful. Superficial radiation, oral vitamin A, hormonal extracts, mechanical abrasion, and surgical excision have had little effect. Debridement with a scalpel may reduce troublesome spots. Secondary fungal and/or bacterial infections require immediate attention. In some genotypes, oral aromatic vitamin A preparations have reduced the hyperkeratoses, while others demonstrate increased sensitivity and fragility of the skin.

Our patients had no other abnormalities. A family tree revealed that 14 of 31 people had this skin manifestation, strongly supporting Mendelian dominance. No other serious systemic pathologic processes complicated their lives. Our patients chose 6% salicylic acid in petrolatum, as well as pressure absorbers in their shoes, to reduce the hyperkeratosis.

Dr. Burkhart is clinical professor of dermatology at the University of Toledo College of Medicine in Ohio and clinical assistant professor of dermatology at Ohio University College of Osteopathic Medicine, in Athens.