RESUMEN
We report a case of a 66-year-old woman who presented with acute shoulder pain. Initial radiographs revealed a sclerotic intraosseous lesion in the greater tuberosity with associated cortical erosions and subacromial calcification. The diagnosis of intraosseous calcific tendinitis was confirmed with additional magnetic resonance imaging and nuclear medicine imaging. Within 3 months of conservative measures, the patient's symptoms improved but the radiographic appearance had become more aggressive with a wider zone of transition. After 1 year, the imaging findings continued to change, with the development of subcortical cysts. Correct diagnosis of this uncommon manifestation of tendinitis requires knowledge of how its appearance changes with time.