Spiny keratoderma: A review of case reports and histopathological descriptions.

Spiny keratoderma (SpK) is a rare skin condition characterized by spine-like papules on the palms and soles. The condition is identified under several names such as "music box spine keratosis" and "palmoplantar filiform hyperkeratosis," creating ambiguity in the diagnostic and histopathologic features of the disease. In this study, we reviewed 84 cases of SpK to examine patient demographics, medical history, clinical and histopathological descriptions, and sporadic versus hereditary onset. Notably, the most used histopathological terms were "parakeratosis" and "hypogranulosis," and the most used clinical terms were "spine" and "hyperpigmented." The average age at presentation was 60.1 years with the majority of cases in males. Only 29.8% of cases were associated with a family history of SpK and underlying malignancies were present in 28.6% of cases. This review investigates the frequency of histopathologic and clinical terms used to describe SpK to provide insight into the clinical and histopathological characteristics of this rarely reported condition.