Arthralgia in childhood is an unspecific symptom. One rare cause of arthralgia is hypertrophic osteoarthropathy associated with digital clubbing. We present a child where hypertrophic osteoarthropathy led to the rare diagnosis of an inflammatory pseudotumour of the lung. In a 12-year-old girl with arthralgia and digital clubbing, a chest radiograph disclosed a large round mass in the right upper lobe, and the following chest computed tomography scan showed a large solid homogenous, round, well marginated lesion with little contrast enhancement. A lobectomy of the right upper lobe was performed, and histological examination showed an inflammatory pseudotumour. The postoperative course was without problems: arthralgia and digital clubbing disappeared.