Pachydermoperiostosis Mimicking Inflammatory Arthritis: Case Description and Narrative Review

Pachydermoperiostosis (PDP), also called primary hypertrophic osteoarthropathy (HOA), is a rare genetic disease with typical thickening of the skin (pachydermia) and rheumatic manifestations, with clubbing of the fingers and toes and periostosis of the long bones visible on X-rays, as well as arthritis in large joints sometimes. Case: We describe a 23-year-old man with a complete form of PDP who presented with polyarthritis of the ankles and knees, with clubbing of the fingers and toes. He was treated with a non-steroidal anti-inflammatory drug (NSAID), etoricoxib, and with bisphosphonates (initially pamidronic acid i.v. and later oral risedronate 35 mg weekly). His joint pains and swelling disappeared, so that he could resume his daily activities. After eight years, the periostosis on the X-rays had disappeared. Discussion: The case is discussed, the literature regarding PDP is summarized and the differential diagnosis and treatment options are reviewed. Conclusions: PDP may present as polyarthritis. Clinicians should be aware of this diagnosis, as treatment is available and may improve the outcome of the patient. It is important to rule out secondary HOA due to pulmonary or cardiac disease, gastrointestinal malignancies and liver cirrhosis, especially when the dermatological findings are not typical. Further, acromegaly, thyroid acropachy and rheumatologic diseases should be excluded.