An unexpected, benign cause of increased muscular uptake at bone scintigraphy

Bone scintigraphy was performed in a healthy 30-year-old man because of post-traumatic heel pain. The scintigraphy displayed a bilateral increased uptake of 99mTc-MDP in the pectoral muscles and triceps brachii. Further extensive investigations including muscle biopsy were normal and excluded diagnoses such as polymyositis, myositis ossificans or amyloidosis. The abnormalities were in fact explained by physical exercise performed a few hours prior to the radionuclide scan. This was confirmed by the absence of these changes on a second bone scan performed 3 months later. This case shows that muscle exercise should be kept in mind as a cause of skeletal muscle uptake of bone-seeking agents, with the view to avoid unnecessary investigations.