Abstract Hypertrophic osteoarthropathy (HOA) is a condition characterized by digital clubbing, increased periosteal proliferation of skin and osseus tissue at the distal extremities, joint effusions, and arthralgias. Although HOA can occur as a primary disorder, over 95% of cases are secondary to associated intrathoracic pathologies. Pulmonary malignancies are the leading intrathoracic etiology, with non-small cell lung cancer (NSCLC) being the most frequently implicated. The reported prevalence of paraneoplastic HOA in lung cancer ranges from 1-5%. Clinically, HOA may precede the diagnosis of lung cancer by several months up to one year. We present a case of a 58-year-old gentleman with past medical history of COPD and 100 pack-year smoking history who developed paraneoplastic HOA secondary to lung adenocarcinoma, first manifesting as digital clubbing two years prior to his lung cancer diagnosis. Initial chest x-ray imaging performed during outpatient workup for digital clubbing did not demonstrate any evidence of pulmonary malignancy. The patient remained relatively asymptomatic until two years later, when he presented to the hospital due to three months of fevers, fatigue, arthralgias, and myalgias. CT of the chest found a large 3.3 cm spiculated non-calcified mass in the right posterior upper lobe with biopsy later confirming the diagnosis of lung adenocarcinoma. All lung cancer tumor markers were negative. PET scan did not find evidence of metastasis but did reveal periosteal bone reaction. The patient underwent four cycles of chemotherapy with cisplatin and pemetrexed as well as concurrent radiation therapy. Adjuvant immunotherapy with durvalumab was subsequently started and the patient continues maintenance immunotherapy. Re-staging PET scan was performed which demonstrated significant reduction in tumor size, which coincided with improvement in the patient’s symptoms related to HOA including digital clubbing and arthralgias. This case highlights the significance of HOA as a sentinel paraneoplastic manifestation of pulmonary malignancy and the importance of early recognition in guiding diagnostic evaluation. Furthermore, it extends the known interval time between onset of HOA and tumor detection, demonstrating that paraneoplastic HOA can precede lung cancer diagnosis by up to two years. This extended latency period underscores the importance of longitudinal follow-up and ongoing diagnostic suspicion for the evaluation of unexplained digital clubbing. Lastly, this case emphasizes that treatment of the primary malignancy results in resolution of the paraneoplastic syndrome. This abstract is funded by: None
Haines et al. (Fri,) studied this question.