Spiny keratoderma: case series and review

Background Spiny keratoderma is a rare, possibly under-reported, condition characterized by discrete keratotic plugs arising from the palms, soles, or both. It has been associated with malignancies though there is debate as to whether spiny keratoderma is a true paraneoplastic phenomenon. It has also been linked to a variety of non-neoplastic conditions, and several cases appear to be familial. Methods We describe two additional cases of this rare entity and review the literature. Results Thirty-seven cases of spiny keratoderma, including ours, have been reported in the literature. Average age at presentation was 63 years. Earliest age of onset was 11 months. A variety of ethnicities were represented. Ten cases were associated with malignancies. Six cases appeared to be inherited in an autosomal dominant fashion. Several cases were reported in healthy individuals as an incidental finding though it is possible that an associated malignancy or systemic disease will declare itself with time. Treatment is generally unsatisfying with keratotic spines often recurring on cessation. Interestingly, in some patients, the spines resolve after treatment of an underlying malignancy. Conclusions This small case series provides an opportunity to revisit the fascinating phenomena of spiny keratoderma, its possible associations, and implications for follow-up. Due to the association with cancer, all patients presenting with spiny keratoderma should undergo baseline age-appropriate malignancy screening, thence 1-2 times yearly, or as symptoms arise.