Figure 2. Close up of the lesions.
Spiny keratoderma is an infrequent dermatosis consisting of multiple projections located on the palms and soles, with the distinct histopathology feature of a parakeratotic column above a hypogranular epidermis. This entity has been reported under several different names, such as punctate porokeratotic keratoderma, punctate keratoderma, palmar filiform hyperkeratosis, and spiny keratoderma of the palms and soles. Most of the cases described are acquired, although there are also familial cases. Since this disease has been under-diagnosed and under-reported, it is important for dermatologists to keep spiny keratoderma of the palms and soles in mind. We present a familial case of spiny keratoderma and review the literature.
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| Figure 1 | Figure 2 |
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| Figure 1. Multiple keratotic papules on the fingers. Figure 2. Close up of the lesions. |
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A healthy 9-year-old girl presented to our dermatology department with multiple spiky keratotic projections on her palms and fingers since the age of 11 months. The patient described only occasional pruritus. Her mother and grandfather also had these keratotic lesions on their palms and soles. Skin examination revealed multiple 1 to 2 mm spiny papules and hyperkeratotic plugs symmetrically involving the palms as well as the sides of several digits (Figures 1 and 2). A punch biopsy specimen is demonstrated (Figures 3 and 4).
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| Figure 3 | Figure 4 |
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| Figure 3. This picture shows a dense parakeratotic plug. The granular layer is absent beneath the parakeratotic zone (H&E,
x10). Figure 4. A higher powered view of the lesion. There was hypogranulosis but no dyskeratotic or vacuolated keratinocytes underlying this parakeratotic column (H&E, x20). |
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In 1971, Brown reported the first case of keratoderma with numerous tiny spicules on the palmoplantar surface [1]. Later on, this entity has been confusingly grouped under a variety of names, including punctuate porokeratotic keratoderma, porokeratosis punctata palmaris et plantaris, punctate porokeratosis, palmoplantar filiform hyperkeratosis, or minute digitate hyperkeratosis. Spiny keratoderma is characterized by numerous tiny, asymptomatic, keratotic spines on the palms and soles, which resemble the spines of an old-fashioned music box cylinder [2].
Spiny keratoderma of the palms and soles has two distinct forms: a hereditary or benign form and an acquired or idiopathic subset. The hereditary form has an autosomal dominant inheritance and it develops between the ages of 12 and 50. It has no known associations with internal malignancies. The acquired form occurs after age 50 and in some cases it has been associated with an underlying malignancy, although the malignant potential is widely debated in the literature [3, 4].
Microscopically, the parakeratotic column of spiny keratoderma could be confused with the histopathological findings found in porokeratosis. Nevertheless, the clinical presentation of porokeratosis differs, manifesting as hyperkeratotic papules, plaques or annular lesions with a raised ridge at the periphery. Histologically, porokeratosis is characterized by underlying dyskeratotic or vacuolated keratinocytes from which a column of parakeratosis emanates. Ultrastructurally, there is dyskeratosis, vacuolar alteration, or exaggerated tonofilament clumping beneath the parakeratotic column. None of these clinical, histological, or ultrastructural features are identified in spiny keratoderma [5]. Differentiating these two pathologies is important because acquired spiny keratoderma may be occasionally associated with systemic diseases and internal malignancies, including several carcinomas (e.g., melanoma and chronic lymphocytic leukemia), type IV hyperlipoproteinemia, Darier disease, asthma, chronic renal failure, myelofibrosis, and polycystic kidney disease with liver cysts [6, 7].
There is no consistently successful treatment for spiny keratoderma of the palms and soles. Options include mechanical debridement or topical treatments such as salicylic acid gel or 5-fluorouracil cream with occlusion, tacalcitol, urea, and vitamin A or other retinoids [8].
To the best of our knowledge, only a small number of cases of spiny keratoderma of the palms and soles have been reported. This could be related to the fact that this disorder is uncommon and dermatologists may overlook it. In addition, it is possible that patients do not seek medical assistance for spiny keratoderma because most cases are asymptomatic or cause minimal discomfort.
© 2012 Dermatology Online Journal