Large scalp venous malformation in a pediatric patient managed with sclerotherapy and surgery: a case report and review of literature

Venous malformations (VMs) are slow-flow vascular anomalies present at birth that enlarge during adolescence, subsequently causing thrombosis, hemorrhage, and pain. We describe a case of an adolescent male presenting with a large scalp venous malformation. Given the size and location of the lesion, a hybrid approach employing both sclerotherapy and surgical resection was utilized. The VM was successfully removed without complication. A hybrid approach is a safe and effective treatment consideration for immediate management of large venous malformation in higher-risk locations.


Background
VMs are slow-flow vascular anomalies, which usually occur at birth and enlarge in adolescence, subsequently causing symptoms and necessitating management. Although various approaches to the treatment of VMs have been described, there is scarce literature on the management of large scalp venous malformation. Thus, we sought to describe the multidisciplinary management of a large scalp venous malformation in an adolescent male.

Case presentation
The patient is a 13-year-old male with no significant past medical history who was diagnosed with a scalp VM shortly after birth ( Fig. 1 panel 1). The patient was followed conservatively but was referred for neurosurgical consultation after progressive enlargement of the lesion. On examination, the lesion became larger when the patient was supine and became less conspicuous when he was upright. MR imaging of the head revealed a VM with multiple transosseous channels and thinning of the calvarium without obvious defect over the superior sagittal sinus ( Fig. 1 panel 2). Given the concern for significant hemorrhage with a potential scalp laceration and the need for definitive pathologic diagnosis, it was determined the patient would benefit from surgical excision of the lesion with preoperative angiography and embolization.
The patient was first taken to the Department of Interventional Radiology where anesthesia was induced. Using standard aseptic technique, the patient was prepped, draped, and then the VM embolized with direct injection of 30% n-butyl-2-cyanoacrylate (NBCA)/lipiodol mixture (Fig. 2) into the lesion. Once embolization was complete, the patient remained intubated and was transferred to the operating room. He was positioned supine with the head resting on a Mayfield headrest. A bicoronal incision was   (Fig. 3A). The patient was prepped and draped again. The skin was incised and the subcutaneous tissue was dissected around the lesion circumferentially down to the level of the skull (Fig. 3B). A periosteal elevator was used to raise the periosteum and gently roll the lesion medially. Multiple large trans-osseous veins were encountered. These were coagulated with bipolar cautery and divided with Metzenbaum scissors until the lesion, which measured 9 cm by 4.5 cm, was free and removed ( Fig. 3C and D). A Jackson-Pratt drain was left in the subgaleal space and the galea and skin closed in the standard fashion with absorbable sutures. The total estimated blood loss was 400 mL.
On histologic examination, the specimen revealed a vascular malformation with dilated vascular channels with flattened endothelial lining. Smooth muscle was only focally present, and extensive therapy-related changes were noted. The endothelial lining of the vascular spaces was positive for CD31 and negative for PROX-1 (Fig. 4).
The patient tolerated surgery well and recovered in the intensive care unit overnight. He remained neurologically intact and, after the drain was removed, he was discharged home on postoperative day one.

Discussion and conclusions
VMs are slow-flow vascular anomalies comprised of thinwalled, sponge-like channels with deficient smooth muscle [1][2][3]. The incidence of VMs is estimated to be 1 in 10,000, with lesions most commonly located on the head and neck (40%), trunk (20%), or limbs (40%) [4]. On the scalp, VMs are thought to arise from persistent developmental veins communicating between the extracranial and intracranial venous circulations [5]. VMs are typically categorized into 4 types: type 1 are isolated malformations without peripheral drainage, type 2 drain into normal veins, type 3 drain into dysplastic veins, and type 4 malformations represent venous ectasias [6]. Occasionally, communication occurs between extracranial veins and an intracranial venous sinus, which is known as a sinus pericranii [7].
VMs are typically solitary and are caused by germline or post-zygotic somatic mutations affecting individual cells that locally disturb normal vascular development and infiltrate multiple tissue planes [8][9][10][11]. In familial forms of VM, defects in the genes that control the endothelial-cell specific receptor tyrosine kinase have been found, which  [12,13].
VMs often do not become clinically evident until pubertal growth spurts. Typical symptoms include pain due to hematoma formation as well as swelling and destruction of anatomic structures [1,8,14]. During a Valsalva maneuver or when in a dependent position, an increase in size and coloration can occur [4]. Small VMs may not require further workup; however, prior to any surgical intervention, Doppler ultrasound or magnetic resonance imaging is necessary for planning. A computed tomography scan is reserved for VMs involving bony anatomy [8]. Extensive VMs are commonly associated with systemic coagulation profile abnormalities [3,8]. Significant lab abnormalities warrant administration of anti-coagulation therapy peri-procedurally [3].
Because much of the volume of low-flow VMs consists of stagnant intraluminal fluid, percutaneous sclerotherapy, which can be done with liquid (ethanol, sodium tetradecyl sulfate (STS), and bleomycin), semiliquid (NBCA glue, onyx), or solids (particles and absorbable gelatin powder), is widely advocated as the treatment of choice [8,12,[15][16][17][18][19][20]. Surgery is reserved for select cases not amenable to sclerotherapy, VMs that are large and disfiguring, or for whom embolization alone is insufficient.
Large scalp VMs are rare, and management varies depending on the size and location of the lesion. Upon review of the literature, we found only one case series that reported two small scalp VMs (2 cm), which were managed with a single stage NBCA embolization and surgical resection [21]. At our institution, our preference is to use STS foam for type 1 VMs. The foam remains in place, creating endothelial inflammation and scarring with tissue reduction, which is especially effective for lesions in cosmetically challenging locations. For type 2 and 3 VMs such as this case, we prefer 30% NBCA/ lipiodol mixture 30%. Excision is usually planned if size is a consideration or if the VM is in a joint space. This is the first published report of successful singlestage treatment of a large scalp VM using sclerotherapy and surgery. This hybrid approach is a valuable treatment consideration for the management of large VMs in higher-risk locations as it limits anesthesia events and blood loss and treats the lesion immediately.
Abbreviations VM: Venous malformation; NBCA: N-butyl-2cyanoacrylate; STS: Sodium tetradecyl sulfate. Fig. 4 Histology of the venous malformation. A A low-magnification view of the venous malformation which contained several dilated vascular spaces (arrows) with extensive therapy-related changes (asterisk) (hematoxylin and eosin stain, 40 X magnification). B The vessel walls were fibrotic, generally lacked smooth muscle, and were lined by flattened endothelial cells (hematoxylin and eosin stain, 100 X magnification). C Immunohistochemical staining for CD31 highlighted the vascular endothelium (CD31 immunostain, 100 X magnification). D Staining for PROX-1 was negative in the vascular malformation and focally positive in small lymphatics within tissue adjacent to the lesion (inset, arrowhead) (PROX-1 immunostain, 100 X magnification)