Hypertrophic osteoarthropathy as the cause of a super scan of the bone in a patient with prostate cancer: a case report

INTRODUCTION Prostate cancer is known to have a tendency to metastasize to bone. Skeletal scintigraphy can be used to show multiple lesions. Diffuse metastasis, which is not infrequent in prostate cancer, can also be suspected on the basis of a 'super scan'. However, this phenomenon in nuclear medicine has several other causes that need to be considered. CASE PRESENTATION A patient with a history of prostate cancer presented with pleural fluid, peripheral edema and bone pain. A super scan of the bone was found which suggested diffuse skeletal metastasis of the prostate cancer but the patient also had a prostate specific antigen level which was not compatible with this diagnosis. Further investigations revealed the paraneoplastic phenomenon of hypertrophic osteoarthropathy, related to an incurable carcinoma of the lung, to be the cause of the super scan. CONCLUSION A super scan is characterized by a high bone to soft tissue ratio on skeletal scintigraphy, with a uniform symmetrical increase in bone uptake and diminished to absent renal visualization ('absent kidney sign'). It can be seen in a variety of diseases in which there is a diffusely increased bone turnover. Diffuse skeletal metastasis of a well-differentiated prostate carcinoma is unlikely to be the cause of a super scan when the prostate specific antigen level is not elevated. This is the first report of a super scan due to pulmonary hypertrophic osteoarthropathy which can be seen in lung carcinoma and other pulmonary diseases.