Idiopathic clubbing in a young male

Background: Digital clubbing is a common sign of underlying systemic illness, particularly cardiopulmonary or gastrointestinal disease. Idiopathic clubbing is extremely rare and is often a diagnosis of exclusion. Primary hypertrophic osteoarthropathy (PHO), a rare genetic disorder, may initially present with isolated clubbing, creating diagnostic uncertainty. Case Presentation A 26-year-old previously healthy male presented with progressive swelling and broadening of the fingertips and toes over two years. Examination revealed grade 3 digital clubbing of all four limbs. He had no systemic symptoms such as fever, or any respiratory, cardiac, or gastrointestinal complaints. There was no relevant family history or history of cyanotic spells in childhood. Investigations revealed a normal chest X-ray and echocardiography. High-resolution CT thorax showed a few fibrotic bands in the medial segment of the right middle lobe. Oxygen saturation was 98% at room air. Ultrasound abdomen, CBC, LFT, RFT, ESR (13 mm/hr), and CRP (10 mg/L) were within normal limits. Viral serologies (HIV, HBsAg, HCV) were negative. ANA was negative, and thyroid profile was normal (TSH 5.0 mIU/L with normal T3 and T4). X-rays of hands and feet revealed no periosteal reaction. Discussion: This case highlights the diagnostic challenge between idiopathic clubbing and early PHO. The lack of systemic features, normal oxygenation, and absence of radiological signs point toward idiopathic clubbing. However, early or incomplete PHO cannot be excluded entirely, and longitudinal follow-up is required. Conclusion: In rare cases like this, idiopathic digital clubbing should be considered after excluding systemic, infectious, and autoimmune causes. Follow-up is essential to monitor for progression to primary hypertrophic osteoarthropathy or emerging secondary etiologies.