Pachydermoperiostosis (PDP), a rare genetic disorder previously known as primary hypertrophic osteoarthropathy (HOP), is characterised by pachydermia, digital clubbing and periostosis. Arthritis is a less common but important clinical feature, manifesting in adolescence or early childhood, often misdiagnosed as inflammatory arthritis (RA, PsA, SpA etc). Sometimes it mimics common metabolic bone diseases like rickets or hypophosphatasia. This case report explores the diagnostic journey of two siblings with heterogeneous age spectrum for disease onset, started with musculoskeletal deformities & digital clubbing, later targeting joints, causing synovitis with functional impact similar to other inflammatory arthritides, with good response to available therapeutic options including csDMARDs as well biologics. It also highlights major diagnostic challenges while differentiating PDP from other childhood rheumatological conditions among families with two or more similar cases. Consanguinity is a risk factor so; emphasis should be on genetic counselling in unravelling familial cases where genetic testing is unavailable.