Case report: hypertrophic osteoarthropathy improves with immune checkpoint inhibitor therapy.

We report a case of a 66 year-old male with recurrent stage IIIA non-small cell lung cancer (NSCLC) and no prior arthritis or bone disease who developed hypertrophic osteoarthropathy (HOA) prior to immunotherapy treatment. Approximately one month after the first durvalumab infusion and without other interventions for symptom management, the patient reported improvements to his hand pain, with complete resolution of symptoms after five durvalumab treatments. Repeat x-ray after nine cycles of durvalumab showed decreased periosteal thickening of the phalanges bilaterally. He had no evidence of recurrent NSCLC based on serial computed tomography one year after durvalumab initiation. To our knowledge, there are no documented reports on the isolated effect of immune-checkpoint inhibitor (ICI) therapy on HOA. This case suggests that durvalumab may have a positive role in the management of HOA in NSCLC patients. Further research is needed to better understand the interaction of ICIs, HOA and other paraneoplastic syndromes.