A 67-year-old man with a past history of resected basal cell carcinoma, high blood pressure, and diabetes mellitus was referred to our dermatology department for assessment of lesions on the hands that had appeared 3 months earlier. Physical examination revealed multiple keratotic spines measuring 1mm on the palmar surface of both hands (Fig. 1A and B). Examination of the rest of the skin surface revealed no other significant abnormalities. The patient reported no constitutional symptoms or associated systemic symptoms. With a clinical diagnosis of spiny keratoderma and given that this is considered to be a paraneoplastic skin condition, we performed a battery of tests, which were negative, and full-body computed tomography, which revealed a solid cortical nodule with a maximum diameter of 2cm in the left kidney (Fig. 2); the nodule was resected and histology was compatible with clear cell renal cell carcinoma.

Figure 1

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Figure 2

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Spiny keratoderma is rarely reported in the literature and is associated with diabetes mellitus, chronic kidney failure, and different tumors, including esophageal carcinoma, laryngeal squamous cell carcinoma, malignant melanoma, and lung adenocarcinoma. In most cases, its appearance has preceded development of the tumor, although it has not been possible to demonstrate a causal relationship in all cases. Its asymptomatic nature means that it may go unnoticed. Treatment with topical and systematic keratolytic agents achieves an uneven response.