Secondary hypertrophic osteoarthropathy caused by non-pleural or pulmonary tumors

Hypertrophic osteoarthropathy (HOA) is a rare paraneoplastic syndrome characterized by digital clubbing, periosteal reaction, polyarthralgia, arthritis, and synovitis. Herein, we report a case series of patients with secondary HOA caused by non-pleural or pulmonary tumors. The radiologic databases of 2 tertiary university hospitals were retrospectively screened for secondary HOA patients. In addition, a systemic review of the published case reports. Only HOA cases with non-pleural or pulmonary malignancies were involved into the study. HOA in primary pleural or pulmonary malignant or benign disorders, as well in inflammatory diseases were excluded. In all cases, plain radiography was performed and clinical signs were documented. In our databases, 6 patients with secondary HOA were identified. In addition, the systemic review yielded 24 eligible patients. The most prevalent primary tumors were nasopharyngeal carcinoma and esophageal cancer in 6 patients (20%), respectively. In 17 patients, (56.7%) HOA was associated with lung metastases, and in 10 patients (33.3%), no lung metastases were detected. In 14 patients (46.7%), HOA was symptomatically before a tumor diagnosis was made. Plain radiography displayed typically features with periostal enlargement in every case. This study is the first report about secondary HOA caused by non-pleural or pulmonary tumors. Various primary tumors were identified, including several rare tumors such as sarcomas. HOA is a rare disorder with typically radiologically findings, which is not only associated with lung cancer or pleural mesothelioma and can even occur in tumor patients without lung metastasis.