Ab1419 Clinical Analysis of Four Cases of Pachydermoperiostosis

Background: Pachydermoperiostosis is a rare genetic disorder primarily impacting the skin and skeletal system. This condition is characterized by a range of symptoms including thickening of the skin (pachydermia) and abnormalities in bone growth and formation (periostosis). The exact etiology of Pachydermoperiostosis remains unclear; however, it is thought to be influenced by genetic legacy transmission. Objectives: Pachydermoperiostosis is a rare genetic disorder affecting the skin and skeletal system. This study aims to elucidate its clinical features through a case series, enhancing the understanding and diagnostic approach of the disease. Methods: We retrospectively analyzed clinical data from four patients diagnosed with pachydermoperiostosis at Sun Yat-sen Memorial Hospital, Sun Yat-sen University, from 2017 to 2023. This analysis included clinical presentations, laboratory findings, imaging results, and genetic testing. Results: The patients, all male, had a mean age of 22 years (range 21-23 years) and an average onset age of 15 years (range 9-18 years). Notable family history included one patient with an affected uncle and another with consanguineous but asymptomatic parents. Common symptoms were clubbed fingers/toes, skin thickening, and acne. Other findings included frontal wrinkles, nasolabial fold thickening (in three patients), hyperhidrosis (in two), and joint swelling/stiffness (in one). Three patients showed elevated carcinoembryonic antigen levels. Imaging revealed turbinate hypertrophy, meningeal thickening, scalp furrow changes, and periosteal thickening in the phalanges, tibia, fibula, ulna, and radius. One case presented with recurrent hypokalemia and was diagnosed with potassium-losing nephropathy. Genetic analysis identified a homozygous mutation in the SLCO2A1 gene (c.1406C>T, p.Pro469Leu) in one patient, predicted as pathogenic by REVEL, SIFT, and Polyphen2 software. This mutation, previously reported in a compound heterozygous state, was found in asymptomatic parents, suggesting autosomal recessive inheritance. Conclusion: The study highlights that pachydermoperiostosis predominantly affects adolescent males and presents with diverse symptoms including skin and skeletal changes, elevated carcinoembryonic antigen, and in some cases, potassium-losing nephropathy. The identification of the SLCO2A1 gene mutation (c.1406C>T) as a potential autosomal recessive pathogenic variant underscores the genetic underpinnings of this rare condition. REFERENCES: NIL. Acknowledgements: NIL. Disclosure of Interests: None declared.