Primary Hypertrophic Osteoarthropathy (Pachydermoperiostosis): Two Brothers Misdiagnosed As Inflammatory Arthritis

Primary hypertrophic osteoarthropathy (Pachydermoperiostosis) is a rare, inherited genetic disorder of the skeleton and the skin, characterised by clubbing of the fingers, thickening of the skin especially of the face and forehead (pachydermia) and periostosis. Patients often present with pain and swelling of the knees and ankles. The diagnosis is often delayed because the skin manifestations are often overlooked. We report the case histories of 2 brothers with PHO who presented with pain and swelling of the knees and ankles, initially thought to have primary inflammatory arthritis. We believe they have the autosomal recessive type caused by the SLCO2A1 gene mutation. This subtype affects mainly males.