Hypertrophic osteoarthropathy in nasopharyngeal carcinoma patients: two cases report.

Hypertrophic osteoarthropathy (HOA) is a rheumatic disorder characterized by digital clubbing, bone pain, and arthralgia. HOA can be idiopathic or secondary to a variety of pulmonary, cardiogenic, or malignant disorders. We present 2 male patients, aged 46 and 42, with advanced nasopharyngeal carcinoma (NPC) who developed HOA 1-4 years after radiotherapy. Differential diagnosis between HOA and coexisting bone metastasis must be made with caution. We found bone scintigraphy to be the most sensitive tool to distinguish between these 2 disease. Intense symmetrical uptake of radioisotope along the cortex of long bones, so-called parallel tract sign, is typical. Plain radiographs demonstrating prominent periosteal reaction were also effective for this. The rheumatic manifestation of HOA was paraneoplastic and related to pulmonary metastasis. The clinical manifestation of the 2 patients suggested that pulmonary metastasis should be suspected in NPC patients when HOA appears.