Case of atypical femoral fractures that mimicked the typical imaging findings of prostate cancer‐induced bone metastasis

Introduction Atypical femoral fractures are atraumatic or minimally traumatic fractures and rare side effects of bone resorption inhibitors. Bone resorption inhibitors are frequently used in the treatment of prostate cancer. Case presentation A 62‐year‐old man complained of difficulty in walking and left lower limb pain. Androgen deprivation and denosumab therapy for prostate cancer‐induced bone metastasis was initiated 27 months ago. Even though the prostate‐specific antigen level did not increase, imaging studies indicated the possibility of bone metastasis. The patient underwent bone biopsy; however, no malignancy was detected. Afterward, he had a fall, causing a complete fracture in his left femur. Conclusion Atypical femoral fractures occasionally mimic typical imaging findings and outcomes of bone metastasis. This case is important for recognizing such cases.