Primary hypertrophic osteoarthropathy with anemia as assessed by ¹⁸F-FDG PET/CT

Primary hypertrophic osteoarthropathy (PHO), also known as pachydermoperiostosis, is a rare genetic disorder with autosomal inheritance. We present the case of a 31-year-old male with a disease onset at 12 years of age, initially presenting as digital clubbing of the hands and feet and ankle joint hypertrophy. The clinical phenotype progressed significantly by age 17, with the development of marked facial skin thickening, deepened centripetal skin folds, a corrugated scalp, hypertrophic alae nasi, acne, ptosis, and palmoplantar hyperhidrosis. Anemia was identified at age 19, accompanied by persistent fatigue, followed by the onset of bilateral knee joint pain two years later. Fluorine-18-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) imaging revealed a constellation of findings that can be grouped into three categories: (1) skeletal: cortical thickening and periosteal reaction in the long bones of the lower limbs, along with extensively increased bone marrow density throughout the skeleton; (2) soft tissue: diffuse thickening of the cranial and facial skin, and multiple para-spinal soft tissue foci; and (3) systemic: cardiac findings suggestive of anemia-related adaptation. Genetic analysis confirmed the diagnosis by identifying heterozygous mutations in the SLCO2A1 gene (c.290G>A [p.R97H] and c.1295+1G>A), establishing PHO complicated by anemia.