Angioembolization of Scrotal Arteriovenous Malformations: A Case Report and Literature Review

Arteriovenous malformations (AVMs) of the scrotum are rare lesions, usually diagnosed incidentally during the evaluation of scrotal masses or infertility. It could be presented with acute bleeding or acute pain. We are presenting a case of painless bilateral infiltrated scrotal mass (more advanced in the left side) developed dramatically over a year, no other symptoms existed. The diagnosis was made using duplex ultrasound (DUS), computed tomography arteriography (CTA), and digital subtraction angiography (DSA). Three sessions of angioembolization were performed and followed by surgical resection of the left side of the scrotum.


Introduction
Scrotal swelling is a very common condition in medical practice. Differential diagnosis includes benign lesions that affect any component of the scrotum (testicles, soft tissues, and vascular plexus), malignancy, metastases, and infection.
Benign vascular lesions are common in adult males. Varicoceles are the most common lesion, and the rarest is arteriovenous malformations (AVMs). These lesions may present in a broad spectrum of symptoms such as swelling, bleeding, acute pain, sensation of heaviness, and mass-like structure.
AVMs are rare congenital abnormal underdeveloped vascular lesions that grow with the child. They present with a mass-like structure with audible or tangible bruit. The duplex ultrasound study shows high systolic flow, low resistive index, and arterialization of venous waveforms. Magnetic resonance imaging (MRI) helps to define the extent of the AVM and the adjacent tissues. Angiograph shows a rapid transit shunting of contrast agent from feeding arteries to enlarged veins through an underdeveloped vascular plexus [1].
The most common locations of arteriovenous malformations (AVMs) are intracranial, followed by extracranial head and neck, extremity, and truncal and visceral sites. However, congenital scrotal AVM is a rare condition [2].
We are reporting a case of huge scrotal AMV managed by angioembolization. We also reviewed data from other similar reported cases in the medical literature.

Case Presentation
A 19-year-old male patient presented to our center in September 2017 with progressive diffused swelling in the scrotum. The swelling developed dramatically over the previous year with flashing skin and local warmth. There was no pain, urological symptoms, or bleeding. No medical or trauma histories were reported.
Physical examination revealed an asymmetric diffused scrotal swelling (more progressed in the left side) (Figure 1), local warmth, and scrotal skin flashing. By palpation, there was no pulse or thrill. Only the right testicle was palpable.
Duplex ultrasound (DUS) showed prominent vessels exhibiting both venous and arterial components ( Figure 2), with unusual high flow velocities, and dilated veins up to 1 cm in width. The skin thickness was 2 mm at its max.
Computed tomography arteriography showed a large AVM in the scrotum occupying almost all the scrotal sac indenting the testicles that look slightly small, the left testicle was encircled by the malformation. The veins seen were also dilated reaching diameters of 1 cm denoting varicoceles.
The AVM has its arterial supply from the internal iliac arteries and at least one of its veins drained in the left common femoral vein.
Digital subtraction angiography (DSA) demonstrated large AVM in the scrotum being centered mainly on the left side with multiple feeding vessels originating from the anterior division of internal iliac and common femoral arteries bilaterally more apparent from the left sides.
The feeding vessels in the left side were the internal pudendal artery, the superficial external pudendal artery arising from the common femoral artery, and the deep external pudendal artery arising from the deep femoral artery.
In the right side, the internal pudendal artery and a small branch of superficial pudendal artery were noticed.
The conventional scrotal vascular territory is divided into two parts: anterior one-third and posterior two-thirds. The anterior one-third is supplied by the superficial and deep external pudendal arteries, branching from the femoral artery. The posterior two-thirds is supplied by the internal pudendal artery, branching from the internal iliac artery [3] ( Figure 3). The deep external pudendal could be a branch of the deep femoral artery.
Multiple sessions of angioembolization were performed using coils and particles followed by a total resection of the left mass. The patient was informed with all the predictive complications of the procedure.
The first session of embolization was performed in 28/9/2017 in which the left internal pudendal artery and some branches of the superficial external pudendal artery were embolized (Figure 4).
In the second session, one week later, the rest of left superficial external pudendal artery branches were embolized (Figures 5(a)-5(c)). A third session of embolization was needed after two weeks to complete the embolization of the left deep external pudendal artery (Figures 5(d)-5(f)).
Surgical resection was performed in the following day to resect the whole left side of the scrotum, the left testicle was fixed to the right side ( Figure 6).
The histopathological study of resected lesions showed vascular vessels with variation in diameters, some hyaline degeneration in the vessels wall and abnormality in arteriovenous structure.
The follow-up during the next 12 months was favorable with good healing of the scrotal incision and no recurrence of lesion ( Figure 7).

Literature Review
There are many types of vascular lesions that affect the scrotum or the testicle, Sule et al. [4] divided these into four main types: (1) Varicoceles: common lesions that affect the spermatic cord.

Discussion
Scrotal AVMs are uncommon lesions in medical practice with many types of treatment approaches. There is no medical study to support one approach over another due to the scarcity of this condition. Although embolization of feeding vessels helps in reducing the risk of massive bleeding during surgical resection in most cases, it also raises the risk of radiation complications including malignancy, sperm DNA mutations, and permanent damage to the testicular tissue.
Laboratory tests were limited to the patient's condition. Although sperm analysis was commonly abnormal, it was not a routine test, especially in cases of acute pain or bleeding or with patients who refused to do the test (as in our case).
Percutaneous sclerotherapy into the nidus has been described in low-flow vascular malformation treatment. To    Case Reports in Vascular Medicine our best knowledge, the case written by So et al. is the only case report that described an endovascular method to treat a scrotal AVM with transcatheter coil embolization and percutaneous sclerotherapy. In treating the scrotal lesion with direct puncture, which is a very painful procedure, general anesthesia is required to reduce pain and minimize patient movement. In addition, compression during injection helps in localizing the sclerotherapy and reducing the embolic risk [3]. Embolization materials were variable (coils, gelatin sponge, polyvinyl alcohol sponge, butyl cyanoacrylate mixed with lipodol, particles, and onyx); in our case, we used coils and particles.
Choosing the embolization agent depends on the indication and the experience at hand. Each agent has its specific advantages and disadvantages. Factors influencing the choice of material comprise the size of the target vessel, flow velocity, and duration of embolization (permanent/temporary), see Table 2 [19].
Skin necrosis was described in some cases with angioembolization treatment. Later, surgical approach was needed to remove the necrotic tissue (as in our case). Some of the possible complications for embolization procedure [20] in pelvic area are as follows: (i) Necrosis of the skin, bladder, or other intraabdominal organs has also been described especially with sever unspecified embolization  Case Reports in Vascular Medicine (ix) DNA mutations of sperm cells/ovarian cells or infertility due to radiation Conservative approach with periodic assessment was an option in some cases especially in young asymptomatic patients.

Conclusion
The scarcity of scrotal AVMs and the variety of medical approaches present a challenge in both diagnostic and treatment approaches.
We should think of AVMs in patients with rapidly developed lesions despite other symptoms such as pain or bleeding, without neglecting other deferential diagnoses, mainly tumors and infections.
Doppler US is very helpful for diagnosis of these lesion but is not sufficient for planning the management. Patients should be fully informed about the complications of each treatment plan in order to give an informed consent.
The management should consider the individuality of each case.

Limitations
We could not do a sperm count (because the patient refused). There was no intervention in the right side of the scrotum due to the hesitation of the patient.

Consent
The patient gave written informed consent to the publication of his case details and clinical photographs.

Conflicts of Interest
The authors declare that there are no conflicts of interest regarding the publication of this paper. One-year follow-up, no recurrence