Symmetrical nail bed uptake on a 99mTc-HDP bone scan in a patient with Wegener’s granulomatosis

Abstract

A Tc-HDP bone scan was performed in a 48-year-old man because of diffuse pain in the extremities and involuntary weight loss. The planar whole-body scan showed no pathological skeletal uptake. However, a rare symmetrical uptake was detected corresponding to the nail bed of all fingers and toes (top row). Upon clinical examination of the nails there was no obvious visible cause of the scintigraphic findings. The patient was subsequently diagnosed with Wegener’s granulomatosis. After 7 weeks of steroid and cyclophosphamide therapy a repeat bone scan revealed a slight decrease in uptake intensity (bottom row). Soft-tissue uptake on a bone scan has been described in numerous case reports and is often related to heterotopic calcification and/or altered regional vascularity [1]. Nail changes occur in many systemic diseases including vasculitis [2] and are often preceded by some sort of vascular pathology. The typical nailfold pathology present with high frequency (>90%) in Wegener’s granulomatosis is caused by avascular areas, and has been found irrespective of clinical digital vasculitis [3]. Hypoxic and ischaemic conditions in extraosseous tissue can result in Tc-MDP uptake due to the deposition of calcium [1]. Conversely, finger clubbing is associated with increased vascularity in the nail bed, and can occasionally be seen on a bone scan [4].