Hoffa' s fat pad disease usually occurs in young active patients participating in activities involving repetitive microtrauma to the knee joint. No specific radiographic findings associated with the disease has yet been defined. We report an elderly patient who presented with a 12-month anterior knee pain and limited knee extension, without any trauma history. Radiographs showed a calcified soft tissue mass in the Hoffa's fat pad. Magnetic resonance imaging showed the lesion had a generalized heterogeneous hypointensity on T1- and T2-weighted images and a poorly defined margin. The lesion was excised arthroscopically, and histopathological examination revealed fat pad adipocyte necrosis, mucoid degeneration, and dystrophic calcification, suggesting Hoffa's disease. The present report indicates that Hoffa's disease can occur in elderly patients with no trauma history, can be associated with a calcified lesion on radiographs, and can be linked to infrapatellar fat pad degeneration in such patients.