254 J Orthopaed Traumatol (2010) 11:251–255 Fig. 5 Intraoperative images (a–c). The brachial artery and the pseudoaneurysm were isolated and the artery was controlled with nylon tapes (a); the pseudoaneurysmal sac was opened and the thrombus removed (b); a 7-cm arterial segment including the pseudoaneurysm was resected, highlighting the underlying cartilag- inous spur (arrow) of the osteochondroma, which probably caused the pseudoaneurysm (c); the osteochondroma was resected, and a reversed saphenous vein interposition graft was then performed (d) medium into the mass (Fig 3b). Angiography conﬁrmed the diagnosis of pseudoaneurysm measuring 35 mm of patent lumen and provided a useful map for surgical planning (Fig. 3c). On T2-weighted MRI, an aspect of concentric rings was observed due to the presence of thrombus into the pseudoaneurysm that did not diffusely enhance with con- trast material. In this case, the difﬁculty of recognizing the cartilage cap on T2 sequences because of the overlying pseudoaneurysm, hyperintensity on fat-suppressed proton density (PD)-weighted sequences, and enhancement of the medulla after contrast media could not exclude malignant transformation (Fig. 4a– d). Therefore, surgical exploration was mandatory. At operation, a longitudinal incision was made on the right medial upper arm. The nerve was iden- tiﬁed and preserved. The brachial artery was controlled above and below the pseudoaneurysm with nylon tape (Fig. 5a). The pseudoaneurysm sac was opened and the thrombus removed (Fig. 5b). After retrograde ﬂow was restored, a 7-cm arterial segment that included the pseud- oaneurysmal region was resected, and marginal resection of the osteochondroma was performed (Fig. 5c, d). Reversed saphenous vein interposition graft was then performed (Fig. 5d). The wound was closed and a suction drain was left in situ. At the end of the procedure, there were good radial and ulnar pulses palpable. Specimens of the sac wall 123 and thrombus were negative following histopathological and microbiological examination. Histopathological diag- nosis was osteochondroma. The patient was discharged and followed up in the outpatient clinic. Patient gave consent to the publication of this report. Discussion Pseudoaneurysms are a rare complication of osteochon- dromas and they are more frequent after the end of the enchondral ossiﬁcation phase, when the cartilaginous cap become bony and sharp [17]. A hard swelling is the most common pattern of clinical presentation [17]. The most frequent site of this complication is the distal femur, whereas the arm is an extremely rare site, with only a few cases of pseudoaneurysm of the brachial artery reported in the literature [18–21]. Repair of the arterial injury is sel- dom possible. When an end-to-end anastomosis cannot be performed, graft replacement with the autologous saphe- nous vein or with a synthetic graft is preferred [17]. As a matter of fact, in our case, the extent of the pseudoaneu- rysm made the brachial artery non-reparable, and the vas- cular surgeon opted for a reconstruction with a saphenous vein graft.