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Radial artery aneurysm in the anatomical snuff box: A case report and literature review

Highlights • Distal radial artery aneurysms of the hand are rare.• An aneurysm should be considered in the differential diagnosis of a mass in the hand.• Surgical excision is the standard treatment of choice for upper extremity aneurysms.• Decisions regarding revascularization should be made based on a blood flow evaluation.


Introduction
Upper extremity arterial aneurysms are rare, and distal radial artery aneurysms of the hand are even rarer. We herein report a case of radial artery aneurysm in the anatomical snuff box with the clinical, angiographic, and pathological findings and discuss the etiologies and surgical management according to the published literature.

Presentation of case
A 61-year-old woman presented with a chief complaint of a mass on the back of her left hand. A puncture of the mass was performed at a local hospital, and on aspiration of the arterial blood, she was referred to our hospital due to the suspicion of an aneurysm. The mass had been present for a year and had gradually increased in size. The patient had no history of any underlying medical conditions. A physical examination revealed a pulsatile mass in the left anatomical snuff box (Fig. 1), and the findings on Allen's test was positive. Laboratory examinations showed no evidence of systemic inflammation, metabolic disorders, or autoimmune diseases. Computed tomography showed a 22-mm radial artery aneurysm containing a thrombus. Angiography demonstrated a saccular aneurysm of the distal radial artery (Fig. 2a), and an adequate ulnar and interosseous supply to the digital arteries * Corresponding author.
E-mail address: y-yamamoto.srg1@tmd.ac.jp (Y. Yamamoto). was demonstrated by a study with the radial artery compressed using a compression device (Fig. 2b). Considering the likelihood of aneurysm complications, surgical intervention was performed. Under general anesthesia, upon the patient's request, the aneurysm site was incised (Fig. 3). An excision of the aneurysm and proximal and distal ligation of the artery were performed according to the preoperative Allen's test and angiography results. The pathological examination revealed the disruption of three layers of the arterial wall in most parts of the aneurysm wall, indicating a false aneurysm, and an organized thrombus attached to its lumen (Fig. 4). The postoperative period was uneventful, and the patient was discharged two days after surgery. The patient was symptom-free at three months of follow-up.

Discussion
Upper extremity arterial aneurysms are rare, and radial artery aneurysms are even rarer [1,2]. Previously reported cases of radial artery aneurysms have typically been secondary to penetrating trauma or iatrogenic injury at the level of the wrist. In the present case, the aneurysm was observed in an unusual location, involving the distal radial artery in the anatomical snuff box. The anatomical snuff box is a triangular depression between two tendons, the extensor pollicis longus and the extensor pollicis brevis, where the radial artery lies relatively superficial and unprotected. The most common location of aneurysms of the hand is the distal ulnar artery [2]. Distal ulnar artery aneurysms have been well described as a clinical finding of the hypothenar hammer syndrome [3]. Distal radial artery aneurysms of the hand, however, are reported only  as case reports in the literature. We found 16 cases in 14 reports of radial artery aneurysms located in the anatomical snuff box in the English literature (Table 1) [4][5][6][7][8][9][10][11][12][13][14][15][16][17].
In our literature review, three traumatic false aneurysms [6,9] and one true aneurysm resulting from repetitive occupational injury [14] have been reported. In addition to those traumatic aneurysms, three others were related to underlying vasculopathy [8,10,15], two were arteriosclerotic [4,7], one was a mycotic aneurysm [5], and six remained idiopathic. On encountering a patient with a radial artery aneurysm, it is important to consider and investigate the rarer causes of an aneurysm as well as the history of trauma.
In the present case, no obvious predisposing factors were detected by a careful review of the patient's medical history and preoperative examinations, but pathological findings indicated that a previously unnoticed trauma was the cause of the aneurysm.
The diagnosis of an aneurysm in the upper extremity can be made by the detection of a pulsatile mass during a physical examination. Some patients present with nonspecific symptoms, such as an asymptomatic mass [4,7,11] or hand pain [5]. The misdiagnosis of a ganglion or a soft tissue tumor remains a pitfall. Imaging modalities such as duplex ultrasonography, CT angiography, and  conventional angiography are useful for a definitive diagnosis of an aneurysm and preoperative planning.
Upper extremity aneurysms should be treated, although rupture is thought to be very rare [18], due to the risk of thromboembolic  complications, distal ischemia, and symptoms resulting from nerve compression. Surgical excision of an aneurysm is the standard treatment of choice, and the decision to perform revascularization should be made based on an evaluation of the distal blood flow. In our review of the pertinent literature, out of 16 cases, 10 received excision of the aneurysm and ligation of both arterial ends. In three cases, including two arteriosclerotic cases, an insufficient collateral blood supply was diagnosed by preoperative angiography [4,7,13]. Primary anastomosis or interposition grafting of the radial artery is essential for such cases. In the present case, the decision to excise the aneurysm and ligate the artery was made based on the preoperative Allen's test results. Additionally, we confirmed the safety of the ligation of the radial artery by an angiographic study with the radial artery compressed.

Conclusions
We herein reported a rare case of a radial artery aneurysm in the anatomical snuff box. In our case, the excision of the aneurysm with ligation of both arterial ends was considered to be a safe treatment option. An accurate diagnosis and a careful preoperative blood flow evaluation are necessary for performing appropriate surgical management.