Hypertophic osteoarthropathy and clubbing: the role of prostaglandin E2

• PGE2 seems to have a role in hypertrophic osteoarthropathy/clubbing of different causes. • The measurement of PGE2 and bone turnover markers may be useful for monitoring disease activity. • The use of COX-2 inhibitors can be useful for managing the symptoms related to this entity. Genomic studies support the role of Prostaglandin E2 (PGE2) in the pathogenesis of primary Hypertrophic Osteoarthropathy (HOA), with mutations in the 15-hydroxyprostaglandin dehydrogenase encoding gene resulting in increased PGE2 levels. The aim of this study was to analyse the clinical characteristics, comorbidities, and potential role of PGE2 in primary and secondary forms of HOA and/or digital clubbing. Twenty-two patients (14 men/8 women) aged 15- to 78-years (50.8 ± 14.7) diagnosed with clubbing and/or HOA attended the Rheumatology Department for over 15-years. The authors reviewed the clinical characteristics of the patients, including associated comorbidities, image findings, Bone Turnover Markers (BTM), serum and urinary levels of PGE2, treatment, and the clinical evolution of these subjects. Most patients presented associated clinical conditions for HOA and/or clubbing, with only one, the youngest (15-years old), having primary HOA. Pulmonary disorders constituted the most frequent associated condition. All the subjects evaluated (18/22) presented increased urinary PGE2 levels, with most also presenting increased serum PGE2 values. BTM were assessed in most subjects (21/22), showing increased values in most (15/21), particularly in PINP and CTX. Eight patients were treated with selective inhibitors of Cyclooxygenase-2 (COX-2), improving their symptoms. All subjects with primary or secondary HOA and/or clubbing of the series presented increased PGE2 values, particularly in urine, supporting the role of this mediator in the etiopathogenesis of this disorder. When the treatment of the associated condition is not possible, the use of COX-2 seems to be an effective symptomatic therapeutic approach in this entity.