BackgroundHypertrophic osteoarthropathy (HOA) is characterized by several clinical findings, including arthralgia/arthritis, periostosis, and digital clubbing. It can occur as a congenital condition called pachydermoperiostosis, and more commonly, as a secondary manifestation of pulmonary or extrapulmonary diseases or malignancy. Genomic studies support the role of prostaglandin E2 (PGE2) in the pathogenesis of primary HOA, with mutations in the 15-hydroxyprostaglandin dehydrogenase encoding gene resulting in increased PGE2 levels.ObjectivesTo analyse the clinical characteristics, comorbidities, and the potential role of PGE2 in primary and secondary forms of HOA and/or clubbing and also evaluate the clinical evolution of these patients.MethodsEighteen patients (10 men/8 women) aged 15 to 78 years (49,9 ± 15,6) diagnosed with clubbing and/or HOA were attended in our Rheumatology Department over an 11-year period. We reviewed the clinical characteristics of the patients, including associated comorbidities, image findings, bone turnover markers (BTM), and serum and urinary levels of PGE2, among others. Additionally, we evaluated the treatment and the clinical evolution of these subjects.ResultsMost patients presented associated clinical conditions for HOA and/or clubbing, with only one, the youngest (15 years old), having primary HOA (pachydermoperiostosis). Pulmonary disorders were the most frequent associated conditions, with interstitial lung disease (4 cases), COPD (3 cases), and lung cancer (4 cases) being the most frequent, followed by liver diseases including primary biliary cirrhosis (1 patient), liver cirrhosis (2 patients) and chronic hepatitis C virus (2 patients). All the subjects evaluated (15/18) presented increased urinary PGE2 levels (the highest being observed in primary HOA), with most also presenting increased serum PGE2 values. BTM were evaluated in most subjects (17/18) showing increased values in most (11/17), particularly in PINP and CTx. 4 patients were treated with selective inhibitors of cyclooxygenase-2 (COX-2) presenting, when evaluated, a small decrease in urinary PGE2 titers and partly improving their symptoms, which clearly improved after treating the associated cause when possible.ConclusionIn the present series, all subjects with primary or secondary HOA and/or clubbing presented markedly increased PGE2values, particularly in urine, supporting the role of this agent in the etiopathogenesis of this disorder. Pulmonary disorders, including malignancy and liver diseases, constituted the most frequent associated conditions. The use of COX-2 seems to be an effective symptomatic therapeutic approach in this entity.Disclosure of InterestsNone declared