A 56‐year‐old woman presented with worsening bilateral ankle and knee swelling for 10 months, causing difficulty walking. She reported a 20‐pound weight loss over the same time. She denied family history of arthritis, autoimmune disorders, or malignancy, but did endorse a 45‐year smoking history. She was afebrile on presentation. Lung exam showed diffuse expiratory wheezes and decreased breath sounds in the right middle lung field. She had swelling in her bilateral ankles knees, and wrists as well as digital clubbing. Moderate lower‐extremity muscle wasting was noted, with 5/5 strength in both upper and lower extremities. X‐rays revealed joint soft‐tissue swelling. A chest x‐ray showed a large right‐sided lung mass. Chest CT confirmed a 4 × 6 × 6 cm lung mass in the right lung concerning for malignancy. An endobronchial biopsy revealed adenocarcinoma. An extensive rheumatologic workup was negative, ruling out rheumatoid arthritis, lupus, and other common causes of polyarticular processes. Symptoms of pain and swelling improved with the initiation of chemotherapy for the treatment of adenocarcinoma.
Hospitalist commonly encounter joint pain complaints. Although a rare disease process, hypertrophic osteoarthropathy (HOA), also referred to as pulmonary hypertrophic osteoarthropathy (PHO), should be kept on the differential. HOA is characterized by the triad of finger or toe clubbing, arthritic symptoms in the wrists, elbows, knees or ankles, and periosteal formation in the long bones. Approximately 4.5% of lung cancer patients present with findings consistent with HOA, although <1% may present with the full triad. The 2 most common theories for the etiology of HOA are the mechanical theory and the hormonal theory. The mechanical theory is based in arteriovenous shunting. Vasoactive compounds such as megakaryocytes are not deactivated in the pulmonary circulation, instead reaching systemic circulation and release platelet‐derived growth factor, stimulating vascular proliferation and new bone formation. The hormonal theory postulates that HOA is paraneoplastic in nature. Elevated levels of hormones such as estrogen and growth hormone lead to HOA with resolution of symptoms and normalization of hormone levels after treatment of the malignancy. Imaging of choice is whole‐body bone scintigraphy, although recently PET scans are common. Bone scans indicate either diffuse uptake in long bones or uptake predominantly in the joints. Though the only true treatment is to treat the underlying malignancy, pamidronate has been shown to alleviate some of the pain associated with HOA.
Hospitalists must recognize osteoarthropathies as a potential sign of malignancy, as it can be the initial presentation or indicate disease recurrence. Reemergence of HOA symptoms posttreatment may foreshadows disease relapse, and presentation with clubbing and arthralgia may indicate for lung cancer screening.