Incidence of hypertrophic pulmonary osteoarthropathy associated with primary lung cancer

Background and objective: Although the association of hypertrophic pulmonary osteoarthropathy (HPO) with lung cancer was investigated in the 1960s, the recent incidence of clinically apparent HPO is not known. Data from a large series of patients with lung cancer were analysed, in order to assess the incidence of possible HPO, based on bone scintigraphy, as well as the incidence of clinically confirmed HPO. The clinical features of confirmed HPO were also evaluated. Methods: The medical records of patients admitted with lung cancer between January 1986 and August 2004 were reviewed. Bone scintigraphy showing symmetrical, abnormally high uptake in joints and/or long bones was considered to be suggestive of HPO. Patients who also had finger clubbing and joint pain were considered to have a confirmed diagnosis of HPO. Clinical histories and hormone levels were then investigated in these patients, to identify possible causal factors. Results: Among the 1226 lung cancer patients, 55 (4.5%) demonstrated abnormally high uptake on bone scintigraphy, suggesting possible HPO. Ten (0.8%) patients had clubbed fingers and joint pain and were eventually confirmed as having HPO. Serum hormone concentrations were abnormally high in the patients with confirmed HPO. Conclusions: This retrospective study indicated that 4.5% of lung cancer patients showed findings suggestive of HPO, a frequency similar to that reported previously. However, patients with HPO rarely showed the complete triad of signs. Although increased hormone concentrations may have caused the HPO, further investigation is required to confirm this.