Fig. 1

(A) Initial radiograph taken at the first presentation reveals osteolysis, marginal sclerosis, and calcification in the femur, as well as the loosening of the femoral component. (B) Preoperative radiograph taken 2 years after the first visit reveals progressive osteolysis, marginal sclerosis, and calcification in the left femur. (C) No recurrence of intraosseous chronic expanding hematoma is observed at the most recent follow-up, i.e., 6 months postoperatively. The mass predominantly shows a low-signal intensity on a T1-weighted magnetic resonance image (D) and a mixture of low- and high-signal intensities (“mosaic sign”) on a T2-weighted magnetic resonance image (E)