Neurogenic and Vascular Tumors of the Head and Neck

PAUL A. KEDESHIAN, MD JATIN P. SHAH, MD, FACS

Neurovascular tumors of the head and neck are a varied group of neoplasms that can present clinically as isolated masses or in association with various familial syndromes. The majority of neurovascular tumors are benign lesions that can potentially exhibit local destruction from expansile growth, while some are overtly malignant, with aggressive growth capabilities and obvious metastatic potential. While the treatment for these lesions is overwhelmingly surgical, the selected treatment must carefully balance the functional and cosmetic sequelae of surgery against the indolent behavior of most of these tumors. This review will separately consider some of the more frequently encountered types of neurovascular tumors, emphasizing general principles of anatomy, diagnosis, treatment, and rehabilitation where applicable.

VASCULAR TUMORS

Hemangiomas

Hemangiomas are the most common tumor of the neonate/infant, occurring most often in the head and neck.1 The terminology used to categorize these predominantly pediatric vasoformative tumors can be quite confusing and cumbersome. While capillary, cavernous, and mixed types of hemangiomas differ from one another with respect to their depth of penetration, a great deal of overlap within a particular tumor can be present.2,3 For the purposes of this discussion, all hemangiomas will be considered together, and the biologic classification proposed by Mulliken and

Glowacki will serve as the basis for distinguishing hemangiomas from other types of vascular malformations.4 In this schema, hemangiomas are defined as vascular lesions: (1) that present in the neonatal period,

(2) that demonstrate proliferative and then involutional growth patterns, and (3) whose endothelial cells exhibit increased mitotic activity during proliferation. The other major category of vasoformative growths to differentiate from hemangiomas are the vascular malformations, described as neonatal growths that: (1) fail to involute, (2) grow proportionately with the infant, and

(3) demonstrate no endothelial cell proliferation.4

Anatomy

Head and neck hemangiomas, comprising as many as 0.5 percent of all head and neck neoplasms, commonly present at cutaneous sites (scalp, neck, face, ear, lip, nose), although they may arise within the musculature or deep soft tissues of the head and neck, as well as within the mucosa of the upper aerodigestive tract (subglottic larynx).5 Vascular malformations on the other hand, usually are restricted to specific dermatomes, frequently presenting within the cutaneous territories innervated by one of the branches of the trigeminal nerve. The discussion that follows concentrates exclusively on hemangiomas of the head and neck.

Diagnosis

Hemangiomas usually present as erythematous, raised, mobile, cutaneous masses that appear at or

Figure 16-1. Cutaneous hemangioma.

soon after birth (Figure 16-1). This characteristic appearance, occasionally coupled with the reported history of rapid proliferation during early childhood (with or without subsequent involution), is usually adequate for diagnosis. Accordingly, biopsy of these lesions is rarely if ever performed or indicated unless a malignant neoplasm is suggested by aggressive invasion of local structures.

In those hemangiomas that arise deep within the substance of either the parotid gland or neck musculature (masseter, sternocleidomastoid, scalene or trapezius muscles), a mobile, ill-defined, deep neck mass without any overlying skin changes is the usual presentation (Figure 16-2).5 The diagnosis of these hemangiomas may be confirmed by radiographic imaging with intravenous contrast (CT/MRI) that will demonstrate varying degrees of contrast enhancement.5,6

In the case of hemangiomas of the upper aerodi-gestive tract, the medical history and physical findings may include intermittent stridor (especially with crying or exertion), the concurrent presence of a cutaneous hemangioma (present in approximately 50% of children), or rarely, hemoptysis.7 Endoscopi-cally, the presence of an erythematous mass in the posterior subglottic region is frequently appreciated.8

Treatment

Prior to considering the treatment options available for hemangiomas, the natural history of these lesions needs to be appreciated. The vast majority of cutaneous hemangiomas will spontaneously undergo involution with approximately half having regressed by age 5, 70 percent by age 7, and as many as 90 percent by the onset of puberty.9 However, it must be recognized that, even after complete regression, residual masses of fibrofatty tissue may remain. These masses can cause significant cosmetic and functional sequelae, particularly if a hemangioma arises from the nose, ear or lip.1,9 Thus, determining which hemangiomas require treatment and the type and extent of treatment can be quite complicated.

The objectives of any proposed treatment beyond careful initial evaluation, parental reassurance, and monitoring for the development of complications (ulceration) must be very carefully defined. Exceptions to such a conservative approach to the treatment of hemangiomas are in the case of either a cutaneous hemangioma that arises from the periocular region that may require early treatment in order to prevent the development of disastrous functional consequences (deprivational amblyopia)3 or a sub-glottic hemangioma that may require early treatment for airway compromise.3

In most cases, the surgical excision of all but the most pedunculated, cutaneous hemangiomas that are in a location that permits excision with camouflage of the surgical scar is questionable. The exception to this is that of periorbital hemangioma previously alluded to whose excision is considered a surgical emergency.3 In the case of subglottic hemangiomas requiring treatment for airway compromise, the initial role for surgery may be in the establishment of an airway via a tracheostomy, with laser excision only considered for small, well-circumscribed lesions secondary to the risk of subglottic stenosis.8,10 In the rare situation where an intramuscular hemangioma is suspected of causing functional compromise secondary to the compression of adjacent structures, surgical excision can be accomplished, keeping in mind the higher rate of recurrence of these tumors secondary to their more infiltrative pattern of growth.6

More commonly, nonsurgical modalities are employed for the treatment of hemangiomas. As the physics of lasers have become better understood and the technology for their precise delivery has

advanced, this mode of treatment for cutaneous hemangiomas has gained popularity. Yellow light lasers (X 578 to 985 nm) allow for their light to be preferentially absorbed by hemoglobin with only melanin acting as a mild competing chromophore. These yellow light lasers (which take the form of either a copper vapor laser or a flashlamp pulsed dye laser) allow for selective photo-thermolysis and have been used to treat hemangiomas. However, some of the original enthusiasm for the use of lasers to treat hemangiomas has dissipated as it has become apparent that due to the very superficial depth of penetration of these lasers (approximately

1.2 mm), they are only effective for the most superficial, plaque-like hemangiomas and, if used to treat lesions that have a deeper component, may leave these areas entirely untreated.3

In addition to the use of lasers for the treatment of hemangiomas, intra-tumoral and systemic steroid treatment for massive and life-threatening heman-giomas have long been employed, with approximately one-third of tumors showing a dramatic response within 1 week of treatment.11 Corticosteroids in the range of 2 to 4 mg/kg/day appear to be tolerated quite well with acceptably low levels of tox-icity (growth retardation, immunocompromise, hypertension),3 however, steroids are generally regarded as a temporizing measure to effectively control the sequelae of a hemangioma's proliferative growth phase. More recently, the anti-angiogenic properties of interferon alfa-2a have been used for the treatment of massive and life-threatening heman-giomas,12,13 while the anti-angiogenic properties of TNP-470, an agent initially developed to treat malignant tumors, has been found to demonstrate effectiveness in preclinical hemangioma model systems.14 However, these treatments are not without significant risk as interferon alfa-2a can cause spastic diplegia.11

Cystic Hygroma

Cystic hygromas are rare malformations of the lymphatic system that usually present in infancy or in the neonatal period. While 90 percent of cystic hygromas present by 2 years of age, initial presentation in adulthood can occur.2,5 Unlike hemangiomas, these lesions do not demonstrate spontaneous regression and therefore nearly always require treatment.15

Anatomy and Diagnosis

Although cystic hygromas can occur anywhere in the body, greater than 90 percent of these lesions are encountered in the head and neck, with the vast majority in the lateral neck and very few within the substance of the tongue.15,16 These lesions usually present as soft, easily compressible, fluctuant, ill-defined posterior neck masses that may come to clinical attention following a recent upper respiratory infection (Figure 16-3). Other neck masses that should be considered in the differential diagnosis of cystic hygromas include lipomas, branchial cleft cysts, lymphomas, and thyroglossal duct cysts, however the clinical presentation and history, supplemented by radiographic imaging of the neck (CT with intravenous contrast), will usually make the diagnosis quite apparent.17

Treatment

Cystic hygromas are most successfully treated by complete surgical excision, preserving adjacent neu-rovascular structures, although multiple needle aspirations, the injection of sclerosing agents, and even radiation therapy have previously been employed.18 The growth pattern of many cystic hygromas, with multiple superficial and deep extensions that insinuate between surrounding structures, can make complete removal a formidable challenge and likely accounts for the recurrences not infrequently encountered.15,17 Moreover, multiple potential complications of surgery for cystic hygroma have been described including cranial nerve injury, chyle fistula formation, and wound infection, emphasizing

Figure 16-3. Cystic hygroma of the posterior triangle.

the need for a conservative and meticulous surgical approach to these lesions.15,16,18

Hemangiopericytoma

Anatomy

Hemangiopericytomas are malignant tumors that arise from the capillary pericytes (pericytes of Zimmermann), structures within the outer capillary wall that are responsible for regulating the size of the capillary lumen.19 These mesenchymal tumors can arise in any age group and from anywhere in the body that capillaries are present, with the extremities, pelvis, and retroperitoneum as the most common locations.5 Approximately one-quarter of all hemangiopericy-tomas arise in head and neck sites with half of these originating in the sinonasal cavity, and the remainder arising from the neck, orbit, parotid, and oral cav-ity.20,21 For reasons that are not entirely clear, heman-giopericytomas that arise from capillaries in the head and neck behave in a much less malignant fashion than their non-head and neck counterparts.22

Diagnosis

When it presents in the sinonasal cavity, a heman-giopericytoma frequently causes nasal obstruction and epistaxis. Clinically, an erythematous hemor-rhagic mass is visible (Figure 16—4).23 Radiographic imaging will frequently demonstrate a mass causing bone erosion that manifests enhancement with intravenous contrast administration. The other entities that must be considered in the differential diagnosis of sinonasal hemangiopericytoma include juvenile nasopharyngeal angiofibroma, pyogenic granuloma, and any benign or malignant spindle cell lesion of the sinonasal cavity.23 When it arises from other sites in the head and neck, a hemangiopericytoma often presents as a painless, slowly enlarging vascular-appearing mass that can occasionally invade local structures through relentless growth.24-26

Whether it arises from the sinonasal area or elsewhere in the head and neck, the cytologic diagnosis of hemangiopericytoma, as with other spindle cell neoplasms, can be quite challenging, due to the absence of tissue architecture.19 Therefore, the definitive diagnosis of a hemangiopericytoma usually relies upon suggestive clinical findings coupled with a tissue biopsy that demonstrates a well-vascu-larized submucosal or subcutaneous tumor containing irregular vascular spaces.19

Treatment

The treatment of choice for head and neck heman-giopericytomas is surgical resection. When these tumors arise from the sinonasal region, such a resection frequently involves an anterior craniofacial approach in order to ensure complete tumor exposure and en bloc excision. During such resections, neck dissection is not electively performed as the lungs are the overwhelming site of metastasis rather than the regional lymphatics.5 At other head and neck sites, the surgical approach selected must afford the opportunity to completely encompass the tumor mass.

The results of treatment for head and neck hemangiopericytomas seem to favor a less aggressive biology as compared to the same histology at other body sites, although local recurrence of tumor in as many as 50 percent of patients may occur.22 While the rarity of this tumor's occurrence in the head and neck precludes the existence of large series upon which to directly assess treatment results, if one extrapolates from the results of the treatment of other low-grade sarcomas of the head and neck, small primary tumor size and surgery that can achieve negative surgical margins are important prognostic features.27

Figure 16-4. Hemangiopericytoma of the palate and maxilla.

While the literature includes many case descriptions of the use of radiotherapy for the treatment of hemangiopericytomas, particularly in the case of microscopically positive or close surgical margins or surgically inoperable lesions, the benefit of such therapy is unproven.24'27,28 Finally, isolated descriptions of the use of a variety of chemotherapeutic regimens for distant metastases have not revealed any significant or durable clinical responses.29

Juvenile Nasopharyngeal Angiofibroma

Anatomy

Juvenile nasopharyngeal angiofibroma (JNA) is a rare, benign, vascular neoplasm that arises almost exclusively in adolescent males. JNAs arise in the area of the sphenopalatine foramen, at the junction of the palatine bone, the vomer, and the pterygoid root.30 These tumors receive their predominant blood supply from branches of the external carotid artery (internal maxillary), although an internal carotid arterial supply can also be present.31 With the introduction of computerized tomography (CT), assessment of the true anatomic extent of these tumors became possible, prompting the description of multiple staging systems, all of which attempt to assess the degree to which the tumor has extended out of the nasopharynx.30 32 33 The simplest of these staging systems, first described by Chandler, identifies tumors that are confined to the nasopharynx (stage I), those that have extended anteriorly or superiorly into either the nasal cavity or sphenoid sinus (stage II), those that have extended into the paranasal sinuses or more laterally into the cheek and infratemporal fossa (stage III), and those tumors that extend intracranially (stage IV).32

Diagnosis

JNAs typically present with nasal obstruction and intermittent epistaxis in an adolescent male with nasal endoscopy revealing a vascular nasopharyn-geal or nasal cavity mass (Figure 16-5).3435 Radi-ographically, the presence of a contrast-enhancing lesion in the nasopharynx with variable degrees of extension into contiguous structures may be appar ent (Figure 16-6). Moreover, magnetic resonance angiography (MRA) or conventional angiography can strikingly delineate the vascular nature of these tumors, identify the arteries that constitute their vascular supply, and permit subsequent embolization (Figure 16-7).31,36-38 The differential diagnosis of these nasopharyngeal tumors includes hemangioper-icytomas and antro-choanal polyps.

Biopsy of these tumors is rarely, if ever, indicated and can result in life-threatening epistaxis due to their extensive vascularity.

Treatment

The presumed endocrine-responsive nature of these tumors has long been appreciated, stimulating a trial of androgen-blocking agents as a potential treatment adjunct.39 Despite these and other nonsurgical therapies, the preferred treatment for JNAs is complete surgical excision, often preceded by angiography and embolization to minimize the risk of intraoperative blood loss.31'36,38 Although some regard intracranial extension and/or internal carotid artery vascular supply as contraindications to surgical resection,31 the use of intracranial and skull base approaches for these extensive tumors has been described.37,40 Recently, endoscopic intranasal surgical resection of

Figure 16-5. Juvenile nasopharyngeal angiofibroma (JNA).

JNAs has also been described and proposed for selected small lesions.40,41

Radiation therapy has been proposed as a treatment alternative to surgical resection for extensive tumors,42,43 as well as postsurgical recurrences.44 Total radiation doses of 20 to 30 Gy (approximately 150 cGy/fraction) have been reported to yield nearly 100 percent tumor growth arrest with minimal observable morbidity.42,43 However, the long-term effects of radiation on facial development in this adolescent patient population are not known,40 nor are the potential risks of radiation-induced malignant transformation.45,46 Chemotherapy has even been suggested as a potential treatment option for extensive recurrent JNAs.47

The surgical approach that is used for the treatment of JNA will depend upon the tumor extent that is apparent on preoperative clinical and radiographic examination.40 Surgical approaches include a transpalatal approach for small lesions confined to the midline, a medial maxillectomy approach for lesions with a greater degree of lateral extension, and craniofacial, infratemporal fossa, and facial translocation approaches for more extensive tumors. While no sufficiently large clinical series of various tumor stages exists in order to assess the efficacy of surgery as a single treatment modality, results taken from a variety of small series seem to suggest that surgical resection is associated with a less than 10 percent rate of recurrence in smaller tumors and as much as a 40 percent risk of recurrence in more extensive tumors.31,40

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