Unklare Raumforderung der proximalen Ulna

A 57-year-old master butcher presented with left-sided elbow pain that had been recurring for 20 years. In the clinical examination the patient displayed unrestricted range of motion, a slightly positive Cozen sign and a subtle pressure tenderness over the anconeus muscle. Magnetic resonance imaging and computed tomography revealed a large mass within the metaphysis of the proximal ulnar, which morphologically indicated a chronic granulomatous infection. An open biopsy provided microbiological evidence of colonization with Citrobacter braakii in the sense of a chronic florid inflammation without any indications of malignancy. After extensive curettage and debridement of the defect region, the bone cavity was filled with a combined autologous and allogeneic cancellous bone transplant. The patient also underwent long-term treatment with intravenous and finally oral antibiotics in accordance with the antibiogram. The patient was symptom-free with unrestricted elbow motion and function 3 months later. The present case demonstrates a previously unreported differential diagnosis for elbow pain based on a chronically destructive space-occupying lesion of the proximal ulna. The diagnostic and therapeutic strategies of this rare clinical picture are presented and discussed in detail.