Diagnosis of Lung Cancer in a Patient with Chronic Knee Pain Caused by Hypertrophic Osteoarthropathy

ABSTRACT

Patients with chronic knee pain are common, and symptoms are usually caused by degenerative disorders of the knee joint. Although hypertrophic osteoarthropathy (HOA) is a rare cause of knee pain in patients who visit the department of rehabilitation medicine, clinicians should consider this paraneoplastic syndrome. Herein, we report an uncommon case of hypertrophic pulmonary osteoarthropathy (HPO) in a patient with chronic knee pain who was finally diagnosed with lung cancer. A 49-year-old male was referred to the department of rehabilitation medicine from a local clinic for uncontrolled bilateral knee pain. The plain radiograph and magnetic resonance image (MRI) of the knee showed symmetric periosteal reaction and prepatellar bursitis. For additional evaluation, bone scan was done, and it revealed symmetric linear uptake along the diaphyseal and metaphyseal surfaces of both femurs and tibias, a typical feature of HPO. A plain chest radiograph was taken and showed a mass at the left hilar region. The patient was finally diagnosed with non-small cell lung cancer. After receiving chemotherapy for lung cancer, knee pain improved.