We describe a 55-year-old male with end-stage renal disease due to chronic glomerulonephritis. A kidney transplantation was performed at 52 years of age, and the patient had been treated since transplantation with steroids, azathioprine (AZA) and cyclosporine A (CsA). Three years post transplant, AZA was changed to mycophenolate mofetil (MMF) and allopurinol introduced due to hyperuricaemia, observed since the second month post transplant. Five months later, the patient complained of pain and oedema of right ankle joint. On examination, there were no abnormalities except oedema, reddening and tenderness of the joint. As there were no abnormalities on X-ray, and symptoms were related to soft tissues, the patient received antibiotics and his leg was immobilized for 3 weeks, after which the symptoms exacerbated. A subsequent X-ray performed after this period revealed osteolysis of calcaneus (Figure 1). Magnetic resonance imaging revealed diffuse osteolysis of calcaneal bone stock, extension of pathological tissue into the surrounding soft tissues, with low signal in T_1-weighted scans (Figure 2) and no enhancement after gadolinum administration (Figure 3). The orthopedic surgeon, a specialist in musculoskeletal infections, suspected an inflammatory or neoplastic process, and an excision biopsy of calcaneus was performed. Intra-operatively, no purulent exudate was detected, but suet-like tissue existed inside the calcaneus. Histopathological examination revealed diffuse T-cell malignant lymphoma. There were no other organs involved, as demonstrated in computed tomography of the chest and abdominal cavity. Any clinical symptoms and signs of other skeletal localizations were absent. The subsequent treatment included chemotherapy, followed by local radiotherapy. CsA was withdrawn and the dose of MMF increased. The treatment was quite well-tolerated and renal function remained stable. One year after diagnosis, there are no symptoms and signs of recurrence.
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