A Case Report of Unusual Multiple Minute Digitate Hyperkeratosis

We report a 43‐year‐old woman, in otherwise excellent health, who presented with a 4 year history of an asymptomatic, papular condition described as ‘tiny little spines’ involving the skin. On examination hundreds of discrete, palpable 1‐mm projections were present on the upper torso and arms. Histopathology showed a small focus of acanthotic epidermis forming a small spire. Overlying the subtle epidermal elevation was a column of compact hyperkeratosis with focal parakeratosis. Epidermal atrophy and dermal lymphocytic inflammation, characteristic of Flegel’s disease, were not observed. No features of keratosis pilaris were noted. A diagnosis of multiple minute digitate hyperkeratoses was rendered. Relatively rare multiple minute digitate hyperkeratoses is a non‐follicular disorder of keratinization of unclear etiology. Previously ascribed names include, but are not limited to, disseminated spiked hyperkeratosis and minute aggregate keratoses. A classification scheme with sporadic, post‐inflammatory (recently challenged as another entity) and familial (autosomal dominant) types has been proposed. Other classifications are based on topography and histology or age of onset: early (20’s and 30’s) and late (40’s‐50’s). Paraneoplastic syndromes have been associated with late onset type. In summary, we report a sporadic case of late‐onset multiple minute digitate hyperkeratosis, an unusual and relatively rare disorder.