Punctate Palmoplantar Keratoderma Type 1 With a Multigenerational Family History: A Case Report.

Punctate palmoplantar keratoderma type 1 (PPKP1), also known as Buschke-Fischer-Brauer disease, is a rare inherited keratinization disorder characterized by multiple hyperkeratotic papules on the palms and soles. It is typically inherited in an autosomal dominant pattern with variable penetrance and has been associated with pathogenic variants in the AAGAB gene. We report the case of an 86-year-old man with an asymptomatic palmoplantar dermatosis of more than 50 years' duration who was evaluated during hospitalization for an unrelated medical condition. Examination revealed numerous yellowish-brown punctate and confluent keratotic papules and plaques involving the palms and soles, with marked hyperkeratosis over pressure-bearing areas. Similar palmoplantar lesions were reported in two of his sons and one sister, clinically suggesting an autosomal dominant inheritance pattern. Histopathologic examination of a plantar lesion demonstrated well-demarcated compact orthokeratotic hyperkeratosis overlying an epidermal depression, with irregular acanthosis and no significant dermal inflammation. The clinical presentation, multigenerational family history, and histopathologic findings supported a diagnosis of probable PPKP1. Molecular testing for AAGAB variants was not performed; therefore, the diagnosis was clinically and histopathologically supported rather than genetically confirmed. This case highlights the characteristic clinicopathologic features of probable PPKP1 after more than five decades of evolution and underscores the diagnostic value of a detailed family history in inherited palmoplantar keratodermas.