Keratosis punctata palmoplantaris (KPPP) is a rare genodermatosis with an autosomal-dominant pattern of inheritance. We report the case of a 61-year-old woman who presented with a long history of multiple symptomatic hyperkeratotic papules on the palms and soles. In addition, we review the literature and present the current classification of the heterogeneous group of punctate palmoplantar keratoses, the cutaneous and histologic findings, the differential diagnosis, the possible association with various anomalies including malignancies, and the various treatment options.
Case Report
A 61-year-old German woman whose medical history was significant only for osteoarthritis presented with a long duration of multiple hyperkeratotic papules on the palms and soles. The patient recalled the palmar lesions first appeared at approximately age 15 years. She denied any history of arsenic exposure. Her occupations included gardening and working as a housewife. All cancer screenings appropriate for her age, including mammography, fecal occult blood testing, colonoscopy, and Pap test, were current; no malignancies have been detected to date. Family history revealed 6 other relatives spanning 4 generations with similar lesions on the hands and soles (Figure 1). All family members in the pedigree were generally healthy without any reported history of malignancies. On examination, the patient had multiple 2- to 3-mm discrete keratotic papules over the palmoplantar surfaces that were confluent in areas involving the weight-bearing surface of her soles (Figures 2 and 3). The patient described some tenderness in these areas when standing and walking. Histologically, the keratotic papules revealed a compact hyperkeratotic plug with a slight depression in the underlying epidermis (Figure 4). No parakeratosis or cornoid lamellae were present. The patient was initially treated with daily salicylic acid 40% and urea 40% cream with some improvement of the hyperkeratosis. At follow-up one month later, daily tazarotene 0.1% gel was added, which resulted in further improvement and resolution of the pain after 3 months.
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Comment
The first description of keratosis punctata palmoplantaris (KPPP) was reported by Buschke and Fischer1 in 1910. Three years later, Brauer2 reported a family with clinically similar lesions that appeared to be hereditary. The disorder is thus often referred to as Buschke-Fischer-Brauer disease. Various synonyms have been used to describe this genodermatoses (Table 1).3-7
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Currently, the classification of palmoplantar keratodermas (PPKs) is based on clinical morphology, distribution of the lesions, histology, modes of inheritance, and, in some cases, molecular pathology.3,8,9 The "simple" PPKs, which involve only the skin, can be divided into 3 types: diffuse, focal, and punctate. The punctate PPKs are subdivided into acquired and hereditary forms. Acquired forms include arsenical keratoses and keratosis punctata of the palmar creases. The hereditary forms of punctate PPKs include KPPP (type I punctate PPK, Buschke-Fischer-Brauer disease), spiny keratoderma (type II punctate PPK, porokeratosis punctata palmaris et plantaris), focal acral hyperkeratosis, and acrokeratoelastoidosis.3,7,8
KPPP is transmitted as an autosomal-dominant trait with variable penetrance.6-9 The lesions of KPPP develop over the palmoplantar surface between the ages of 12 to 30 years, with a peak incidence in the second decade, as was the case in our patient. Most reports suggest predominance in black patients with a roughly equal sex ratio overall.4-7 The incidence in one large series is reported as 1.17 per 100,000 people.6 The primary lesions, which typically begin over the lateral edge of the digits, are slightly raised, sharply marginated, round to oval, skin-colored papules. The size of the lesions range between 2 to 20 mm. Over time and with repetitive trauma, the hyperkeratotic lesions become enlarged, turn more yellow-brown, and distribute irregularly over the entire palmoplantar surface. The plantar lesions may coalesce into a more diffuse pattern over the pressure points. The number of lesions per person may range from 1 to more than 40 papules, with an average in one study of 8.3.4 Removal of the deep central portion leaves a depression in which the original lesions will re-form during a period of weeks. The lesions may be accentuated with immersion in water.7
Most patients with KPPP are asymptomatic and are often diagnosed incidentally on examination; however, in some cases, symptoms of burning, pruritus, and pain hindering daily activities, such as walking or manual labor, have been noted.4 Hyperhidrosis is uncommon, but nail abnormalities such as longitudinal fissures, onychogryphosis, and onychomadesis are frequently reported.4,10 The course of the disease is long-term, and spontaneous resolution has not been reported in the literature.
Histologic specimens from KPPP lesions reveal circumscribed compact columns of massive hyperkeratosis and a normal to mildly increased granular layer. There is usually a slight depression in the epidermis beneath the plug (Figure 4).4