A 32-year-old man with a history of kidney transplantation presented with lower limb pain, which worsened when walking. He was using immunosuppressants and had normal renal function. Various tests and imaging studies were conducted, including knee and ankle radiographs, whole-body MRI, and a biopsy of a lesion in the left lateral malleolus. The authors of the article provided detailed information on the patient's case and the diagnostic process.