Giant scalp arteriovenous malformation in a 29-year-old male: case report
SPMC J Health Care Serv. 2016;2(1):7 ARK: http://n2t.net/ark:/76951/jhcs7he64u
1Department of Radiological and Imaging Sciences, Southern Philippines Medical Center, Bajada, Davao City, Philippines;
2Diagnostic Imaging, San Pedro Hospital of Davao City Inc, C Guzman Street, Davao City, Philippines;
3Department of Radiology, Brokenshire Memorial Hospital, Brokenshire Heights, Madapo, Davao City, Philippines;
4Department of Radiology, Davao Doctors Hospital, Quirino Avenue, Davao City, Philippines;
5Department of Radiology, Davao Medical School Foundation, Medical School Drive, Poblacion District, Davao City, Philippines
Correspondence Omar Naseef J Abdua, firstname.lastname@example.org
Received 26 January 2016
Accepted 13 April 2016
Cite as Abdua ONJ, Sanchez MTT, Gaspar-Mateo SR, Bangoy SB, De Castro RJ. Giant scalp arteriovenous malformation in a 29-year-old male: case report. SPMC J Health Care Serv. 2016;2(1):7. http://n2t.net/ark:/76951/jhcs7he64u
Vascular formation within the brain develops through angiogenesis and vasculogenesis.1
Arteriovenous malformation (AVM) results from a disruption of normal vascular differentiation and growth during fetal development.1
The pathogenesis of AVM may be due to a persistent congenital vascular plexus, proliferative capillaropathy, or cellular and molecular differentiation.1
In the general population, the prevalence of AVM is 15-18 per 100,000 adults.1
The different treatment strategies for scalp AVM include transarterial embolization, transvenous embolization, direct percutaneous embolization, electrothrombosis, and surgical excision or ligation.2
Extracranial AVM accounts for 8.1% of all AVM cases.3
Scalp AVM is rare, and is about 20 times less common than intracranial AVMs.4
We present the case of a 29-year-old male with a large scalp AVM, the clinical features of the disease, and our diagnostic and therapeutic approaches.
A 29-year-old male came to our hospital due to a scalp mass. The mass on the right temporal area was noted since birth. It had been gradually enlarging with no associated signs and symptoms until 5 years ago, when the mass had minimal bleeding, which was easily controlled by direct manual compression. A year after, the patient started complaining of on and off headache, exacerbated by exertion, and usually relieved by taking paracetamol. The patient did not consult a physician for his condition until three years ago. The patient was admitted in 2013 so that thorough diagnostic imaging studies could be done. The patient’s past medical, social and family history were unremarkable.
When we first examined the patient, we noted a 15 x 10 x 3 cm bulging, soft, pinkish to erythematous mass on the right temporoparietal area. The lesion was scabbed, irregularly contoured, and nodular. Figure 1 shows a photo taken by the patient a few days prior to his first admission. The mass had a palpable thrill and bruit on ausultation. Vital signs were within normal limits. There were no other systemic abnormalities noted. At this point, we were thinking that the patient could have either a lymphatic malformation, a venous malformation, or an arteriovenous malformation.
Photos of the right temporo-parietal scalp lesion taken by the patient in 2013, prior to surgical excision (A) and in 2015, two years post-surgery and prior to embolization (B), showing a large, bulging, lobulated, nodular, pinkish to erythematosus mass. The lesion had varying external appearance. In the preoperative photo, the lesion has a scabbed, coarse and dry surface (A). In the postoperative photo, the residual mass has more irregular contours with areas of necrosis, ulcerations, and minimal bleeding (B). Computed tomography 3D reconstruction from images taken in 2013 demonstrates the location of the external lesion (C) and the extent of the arteriovenous malformation (D). L – left.
Timeline of the patient’s signs and symptoms, with corresponding diagnostic and therapeutic approaches and clinical outcomes.*
||Signs and symptoms
||Gradually enlarging mass on the right temporoparietal area
||Minimal bleeding of the mass
||Control of bleeding
||Intermitent headache on exertion
||Relief of headache
||Admission for diagnostics
||MRI/CTA/MRA: Scalp AVM with feeding vessels arising from three branches of the right external carotid artery
||Profuse bleeding of the mass after a friable portion was accidentally scratched
||Partial surgical excision
||Came back because of gradually enlarging residual scalp mass, intermittent headache and intermittent bleeding of the mass
||Repeat CTA and MRA
|Successful embolization of the right posterior auricular artery
Successful embolization of the right occipital artery four days after the first emobilization
Attempt to embolize the right superficial temporal artery was unsuccessful
|30cc blood loss
Discharged improved with instructions for regular followup
||Significant regression of the AVM
||Instructions for regular followup
*All signs and symptoms, diagnostics, therapeutics and outcomes pertain to the right temporo-parietal lesion. AVM –arteriovenous malformation; CTA – computed tomographic angiography; MRA – magnetic resonance angiography; MRI – magnetic resonance imaging; NSAID – non-steroidal anti-inflammatory drugs.
Diagnostic and therapeutic approaches
A diagnosis of AVM was considered based on history and physical examination. We did a cranial magnetic resonance imaging (MRI) to confirm our diagnosis. The results showed multiple tortuous and serpiginous flow voids in the scalp, predominantly in the right temporoparietal region (Figure 2). Computed tomographic angiogram (CTA) (Figure 3A) and magnetic resonance angiogram (MRA) (Figure 3B) were also done, which revealed tangled clusters of tortuous, serpiginous, irregularly dilated vessels surrounding the cranial vault, as well as in the scalp, predominantly on the right side, with feeding vessels commencing at the right external carotid artery 5 cm above the common carotid artery. Draining vessels appear in the ipsilateral external jugular vein, with spongiform enhancement located in its communicating vessel. There is consequent thickening of the involved scalp tissue, with nodularity growing extrinsically. The smallest vessels are seen surrounding the scalp with no intracranial insinuation.
The Radiology and Surgery services co-managed the patient. Conventional angiography, the gold standard in AVM diagnosis, was requested by the managing teams to map the AVM nidus, which refers to the tangled blood vessels of the AVM, and the feeders, which are the arteries that supply the AVM nidus.5
AVM mapping provides useful information for planning embolization and possible surgical excision of the AVM. During the course of the diagnostic procedures however, the patient accidentally scratched a friable portion of the mass, which subsequently bled profusely.
Magnetic resonance imaging on axial view, T2 sequence, showing thickened scalp with multiple curvilinear flow voids, predominantly in the right temporo-parietal region.
(2013) Initial computed tomographic angiography (CTA) (A) and magnetic resonance angiography (MRA) (B) done prior to surgery, showing extensive dilated and tortuous arteriovenous structures in the right temporo-parietal area. The major feeding vessels arise from the right external carotid artery (B: red arrow). (2015) Repeat CTA (C) and MRA (D) done two years postoperatively, showing significantly lesser arteriovenous structures. A group of tortuous dilated vessels representing the residual mass remains in the right temporal area (C and D: blue rings).
A radical surgical procedure was subsequently done on the patient to ligate major blood vessels on the right scalp. The patient lost approximately 4,500 mL of blood during the procedure. A non-excisable residual lesion was left on the patient’s right temporal region. A few days after the procedure, the patient was discharged improved and was given instructions to come back regularly for monitoring of the lesion. The patient, however, did not return for follow-up.
Two years after the surgical intervention, the patient came back to our institution due to headache and intermittent bleeding episodes in the area of the scalp lesion. The residual mass in the patient’s right temporal region also gradually enlarged within the time that he did not seek any medical attention. Except for hypokalemia at 3.32 mmol/L, which resolved spontaneously, all laboratory findings for complete blood count, creatinine and electrolytes were within normal limits. Repeat CTA (Figure 3C) and MRA (Figure 3D) revealed that the mass now measured 7.3 x 4.3 x 1.6 cm. There was substantial reduction in the number of multiple tortuous dilated vessels surrounding the cranial vault, face and scalp predominantly in the right. The residual lesion in the temporal region had feeding vessels all arising from the right external carotid artery—superficial temporal, posterior auricular and occipital arteries. We did a conventional angiography (Figure 4), and floor mapping of the AVM showed clear demarcation of the feeding vessels. The plan of the Radiology and Surgery services at this point was to do serial endovascular embolization prior to a repeat surgical ligation to reduce the size of the lesion and prevent recurrence of hemorrhage.
Pre-embolization conventional angiographic image (A), showing the branches of the right external carotid artery (A: green arrow)—the superficial temporal (A: red arrow), posterior auricular (A: yellow arrow) and occipital (A: blue arrow) arteries—supplying the lesion. The points in the posterior auricular artery (A: yellow ring) and the occipital artery (A: blue ring) where Histoacryl® tissue glue was introduced during embolization are also shown. Post-embolization conventional angiographic image (B) demonstrates absence of blood in the areas originally supplied by the right occipital (B: blue arrow) and right posterior auricular (B: yellow arrow) arteries, and consequent dilatation of the right superficial temporal artery (B: red arrow).
We were able to successfully perform endovascular embolization of the right occipital and right posterior auricular arteries successfully. For each vessel, we performed cannulation first with a French 3 (1 mm diameter) Progreat® microcatheter, primed with dextrose 5% in Lactated Ringer’s solution, then subsequently embolized a piece of Histoacryl® tissue glue to the vessel lumen to achieve distal infarction. We attempted embolization of the right superficial temporal artery, but it was unsuccessful due to technical difficulties in cannulating the vessel. The plan then was to monitor the size of the right superficial temporal artery and attempt another embolization when the artery lumen enlarges to a size that can accomodate a 1-mm-diameter microcatheter. An accumulated 30cc blood loss was noted during the two procedures.
The patient came back for followup consultation five months post-embolization. On physical examination, there was significant regression of the remaining scalp AVM which now measured 6.6 x 1.8 x 4.9 cm. There was no recurrence of spontaneous bleeding and headaches post-embolization, and since the scalp mass regressed in size, we decided to temporarily forego with the repeat embolization of the superficial temporal artery and to continue monitoring the patient’s condition.
AVM of the scalp is a rare condition, involving the frontal, parietal and temporal regions. AVM is a consequence of abnormal hemodynamics causing progressive dilation of normal vessels of the region (i.e. supraorbital, carotid and occipital arteries). The vascular lesion, which is seen as a large pulsatile mass or a subcutaneous scalp lump, commonly presents as headache, local pain, and—for some—tinnitus.6 7
Aside from these symptoms, hemorrhage, although uncommon, may develop in the event of large vascular malformations. Our patient presented with a gradually enlarging mass associated with severe headache and massive bleeding.
Differential diagnoses for scalp AVM, like the one found in our patient, include congenital hemangioma (CH) and vascular malformations (VM) such as venous malformation, lymphatic malformation and arteriovenous malformation. We used the modified International Society for the Study of Vascular Anomalies (ISSVA) guideline to differentiate CH and VM according to age of occurrence, sex predisposition, course of the lesion, auscultation, and palpation.3
Both CH and VM are present at birth with no sex predisposition. In CH, the growth of the lesion is complete at birth or the lesion grows proportionately with the child’s growth. Involution may occur rapidly within 6-12 months of life or not at all. In VM, the course of lesion growth is proportional to the child’s growth, and the lesion does not involute. Thrills, bruits, or pulsations are not appreciated in CH, but are common in VM. Our patient’s lesion did not involute, the enlargement had been proportionate with his growth, and we were able to appreciate thrills and pulsations on palpation and bruits on auscultation, so we were inclined to diagnose the lesion as a vascular malformation, particularly an arteriovenous malformation.
The choice of imaging modality in patients with scalp AVM affects the quality of the diagnosis and the therapeutic management. Conventional angiography is the preferred modality for understanding the angioarchitecture of AVM lesions and for ruling out any intracranial component.8
The procedure, however, remains underutilized because it is costly, time-consuming, and invasive. It also requires operator experience, and is associated with a 1.5-2% morbidity and mortality risk.9
CTA and MRA are excellent non-invase and economical alternatives to visualize AVMs.10
Both modalities can be carried out for the differential diagnosis of vascular lesions such as cavernous hemangioma, venous malformations, sinus pericranii, and aneurysms. Advantages of CTA include high image resolution, retrospective creation of thinner sections from source data, improved 3D rendering with minimal artefacts, and shorter procedure time. CTA can also demonstrate related bony structures.9
MRA, on the other hand, can differentiate scalp AVMs from other malformations.7
Our patient’s CTA and MRA revealed multiple tortuous and intensely enhancing vessels on the right side of the scalp, which is indicative of abnormal scalp arteriovenous malformation. We were able to identify the vessels that feed the malformation as three arteries that arise from the right external carotid artery—the superficial temporal, occipital and posterior auricular arteries. There was no evidence of communication of the malformation with the intracranial circulation.
The management approach to scalp AVMs remains a challenge because of the high shunt flow, complex vascular anatomy, and cosmetic changes associated with the lesion.6 11 12
Cosmetic correction and bleeding prevention are the goals of therapy.13 14 15
Ligation of feeding vessels, embolization, electrothrombosis, and introduction of sclerosant into the AVM nidus are the suggested approaches.7 16
In general, preoperative embolization of the nidus and feeders of an AVM greatly helps in reducing the size of the lesion, decreases the risk of massive hemorrhage, and facilitates subsequent surgical treatment.7 17
Surgical excision after successful embolization or ligation of the AVM nidus is an effective method in dealing with large scalp vascular lesions.7 Although embolization followed by surgery has been proven to be beneficial, cure rates are low, unless the AVM is focal and located in a safe anatomic area.18
For our patient, we planned to initially do conventional angiography, which would guide us to plan for embolization and eventual surgical excision. Our patient underwent radical surgical excision before conventional angiography could be done because of persistent bleeding of the lesion. We were able to surgically control the bleeding and ligate some vessels, but a non-resectable portion of the lesion remained and even grew in size. The patient did not submit to regular monitoring postoperatively and only returned when headache and bleeding of the growing residual lesion occurred.
The actual recurrence rate of AVM is unknown, but recurrence is more common among children and rarely occurs among adults with AVM.19
Several possible mechanisms of AVM recurrence have been proposed including persistence and proliferation of an initially occult portion of the AVM that was not removed during surgery, and de novo AVM formation.20
One or a combination of these reasons may explain the growth of our patient’s resected AVM two years post-surgery.
AVM lesions require preoperative conventional angiography to adequate the lesion and plan for therapeutic interventions. Embolization of the nidus and major feeders of the lesion minimizes blood loss during surgical excision. We had to perform surgical ligation on our patient’s scalp AVM before we could do conventional angiography and embolization. This resulted in significant intraoperative bleeding. To properly manage our patient’s postoperative residual scalp mass, which later grew in size, we performed serial embolization two years after the surgery. We were able to successfully embolize two of the three identified feeders, and—as of this writing—we are looking to perform another embolization on the third feeder.
We would like to thank the consultants and residents of the Department of Surgery and Department of Internal Medicine in Southern Philippines Medical Center (SPMC) for co-managing our patient during his recurring admissions.
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