A Rare Case of Distal Humerus Intraosseous Arteriovenous Malformation

INTRODUCTION: Primary intraosseous arteriovenous malformations (AVMs) are rare and have only been occasionally reported. We herein report a histologically proven case of primary intraosseous AVM in the distal humerus which mimicked an osteomyelitis on radiography. CASE REPORT: A 27-year-old male presented with complaints of the right elbow pain and stiffness for the past 3 years. He had initially taken treatment at an outside hospital where he was suspected to have right distal humerus osteomyelitis and underwent curettage and biopsy in June 2017. He presented to us in August 2018 with persistent pain even following the first surgery. Repeat radiographs and computed tomography of the right elbow showed features of osteolytic lesion involving the right lateral humeral condyle just adjacent to olecranon fossa (Fig. 1 and 2). Through posterior triceps, splitting approach para-olecranon lesion was resected by intralesional method (burring), and vancomycin-impregnated calcium sulfate (Stimulan) beads were packed in the defect as infection was suspected (Fig. 3). Clinical improvement and restoration of full range of elbow motion were observed on follow-up. Biopsy report surprisingly suggested arteriovenous malformation. CONCLUSION: Osteolytic lesion was localized in the lateral margin of the olecranon fossa (Fig. 2a and b). To reach the lesion during surgery was a major challenge as localization of the lesion was missed out by the previous surgery. The occurrence of such a condition is rare and it may take even years to correctly diagnose the disease.