Summary

Endoscopic sinus surgery (ESS) has a well-defined role in the management of benign and malignant neoplasms of the sinonasal tract not only in view of the rapidly evolving expertise in the field, but also because of the advances in surgical instrumentation and imaging techniques. The vast majority of the most frequently encountered benign lesions, such as osteoma, inverted papilloma, juvenile angiofibroma, and other vascular and fibroosseous tumors, can be adequately managed by an endoscopic approach. Based on the experience acquired with these lesions, the indications have been expanded to include selected malignant tumors with encouraging results. Over the past 10 years, the skill gained in the endoscopic management of cerebrospinal (CSF) leaks and the repair of large skull base defects fosters the endoscopic surgeons to confidently approach even tumors encroaching upon the anterior skull base.

Based on data collected over a 16-year period at two tertiary care academic centers, the authors provide a wide overview of the indications, surgical steps and tricks, complications, and results of endoscopic surgery in the management of sinonasal neoplasms. Moreover, special emphasis has been dedicated to anesthesiologic management and positioning of the patient during the procedure, perioperative management, and the criteria adopted to perform a “custom-made” postoperative surveillance strategy.

The endoscopic technique must be included in the surgical armamentarium for the management of sino-nasal and skull base tumors. Traditional external approaches still have a role, and they can be associated with endoscopic surgery as hybrid procedures. The surgical team should have the required expertise in all the surgical techniques to intraoperatively modify the surgical strategy according to the specific needs.

Introduction

Over the past 2 decades, the progressive application of endoscopic surgery to the management of benign and malignant tumors of the sinonasal tract has led to a revolution in their treatment. This has been favored not only by the rapidly evolving expertise in the field, but also by advances in surgical technology and imaging techniques. The first reports date back to the 1980s, when experiences in the management of inverted papilloma and osteoma appeared in the literature.1,2 It took some years before the use of endoscopic surgery was extended to the treatment of juvenile angiofibroma3 and subsequently, in a logical progression of indications, to malignant tumors.4,5

At the beginning, these procedures were welcomed with a mixture of criticism and skepticism mainly in view of the fact that the frequently overemphasized concept of “en bloc” resection cannot be met with endoscopic re-sections, thus preventing the possibility of achieving a radical resection, at least in the mind of their opponents. There are now databases of large series that contradict this view. At the same time, limitations to the use of endoscopic techniques in accordance with the nature and extent of the single disease indeed exist. This clearly indicates that even today head and neck surgeons should have traditional external approaches in their surgical armamentarium in addition to endoscopic techniques.

Based on the analysis of the “European Position Paper on Endoscopic Management of Tumors of the Nose, Paranasal Sinuses, and Skull Base,”6 it is evident that virtually all of the results on endoscopic surgery are from retrospective studies and that the accrual of large cohorts of patients is rendered difficult by the rarity of these diseases. Therefore, most series can only be considered as providing evidence at levels III and IV and recommendations at levels C and D.

Selection criteria for endoscopic surgery, preoperative assessment, and surgical technique of resection are quite variable in relation to the nature of the lesion (benign vs malignant) and to the particular histology, so that in this chapter we will provide specific information based on a large experience (840 benign and 331 malignant tumors) gathered during a 16-year period at two tertiary care academic centers in endoscopic surgery.

A Quick Look at Epidemiology, Symptoms, Diagnosis, and Staging

Benign and malignant tumors of the sinonasal tract are rare, with a notable histologic heterogeneity ( Table 43.1 ).7 Although originating from the pterygopalatine fossa, juvenile angiofibroma (see Video 72, Juvenile Angiofibroma ) is habitually included among the benign tumors of the sinonasal tract in view of its common clinical presentation as a mass growing in the nasal cavity. Data on the incidence or prevalence of benign lesions are available only for inverted papilloma (see Video 73, Medial Maxillectomy for Inverted Papilloma, and Video 74, Residual Inverted Papilloma in Frontal, Ethmoid, and Maxillary Sinuses—Draf IIb, Ethmoidectomy, and Exploration of the Maxillary Sinus ) (0.68 to 1.5 cases9 per 100,000 inhabitants per year) and osteoma (3% in CT scans obtained in patients with sinonasal symptoms10). Malignant tumors account for 3 to 5% of all head and neck malignancies,11,12 with an annual incidence of 0.5 to 1 new case per 100,000 inhabitants in Italy.13 For osteoma and inverted papilloma, which are the most frequent benign lesions, no major differences in worldwide distribution is reported; slight variations in the distribution of the most frequent malignant histologies (i.e., squamous cell carcinoma [SCC], adenocarcinoma, adenoid cystic carcinoma, and olfactory neuroblastoma) in different geographic areas are well documented. In general, SCC (see Video 75, Endoscopic Excision of Sinonasal Squamous Cell Carcinoma ) is the most frequently observed histology, but in many countries in central and southern Europe, adenocarcinoma, which is strongly associated with exposure to wood dust particles, is at least as frequent as SCC, with the ethmoid being the most common site. Overall, malignant tumors more frequently affect the maxillary sinus, followed by the nasal cavity and ethmoid. Localizations in the frontal and sphenoid sinuses are extremely rare.

Unilateral nasal obstruction associated with discharge is the most frequent presenting symptom of both benign and malignant tumors. Complaints as proptosis, chemosis, epiphora, deficit of the third, fourth and sixth cranial nerves (CN III, IV, and VI), and visual loss are commonly indicative of a malignant lesion involving the orbit, while a swelling in the maxillary area, loosening of teeth, trismus, and pain in the maxillary area suggest a malignancy of the antrum. Hypoesthesia or paresthesia in the territory of CN V₂ is quite typical of tumors with a tendency to spread along the nerves, as adenoid cystic carcinoma. Not infrequently, these symptoms are underestimated for months or even years, and the diagnosis is made at a late stage when the tumor has already reached intracranial structures, such as the gasserian ganglion. Headache and neurologic deficits are often seen in lesions involving the anterior cranial fossa. Epistaxis is frequently associated with hypervascularized lesions, either benign or malignant, such as angiofibroma and olfactory neuroblastoma ( Table 43.2 ).

The presence at level I and II of palpable neck nodes suggestive of metastasis is a rare event clearly indicating the malignant nature of a lesion. This manifestation is more commonly observed in tumors involving the infrastructure, and in some very aggressive lesions, as sinonasal undifferentiated carcinoma.

Any patient with one or more of these symptoms or signs should be inspected first by endoscopy, which can show a mass occupying the nasal cavity or protruding from the maxillary sinus. The endoscopic appearance can even suggest the nature of the lesion itself, as in the case of an inverted papilloma, which presents as a polypoid gelatinous mass with a papillary appearance, or juvenile angiofibroma, which is typically growing from the area of the sphenopalatine foramen and shows a smooth surface with well-evident capillaries and vessels. Malignant tumors frequently show necrotic-hemorrhagic areas, but the coexistence of inflammatory polyps may obscure the lesion ( Fig. 43.1 ).

At this point, it is common policy to obtain cross-sectional imaging studies, which are meant to give a three-dimensional map of the lesion; to differentiate it from inflammatory changes; to assess the relationships with the pterygopalatine and infratemporal fossae, orbit, skull base, dura, brain, internal carotid artery, and cavernous sinus; to look for bony involvement and its pattern (resorption vs infiltration); and to suggest the nature of the disease. In our experience, these goals are best achieved using magnetic resonance imaging (MRI) (performed before and after contrast administration) because of its unsurpassed contrast resolution. Adequate manipulation of acquisition parameters allows MRI to enhance the difference between lesions and surrounding structures, such as cortical and spongiotic bone, nerves, and vessels. Conversely, computed tomography (CT) should be preferred in the pretreatment work-up of osteoma and fibrous dysplasia: the excellent spatial resolution of modern multislice scanners (0.5–0.75 mm) is of great help in showing how sinus drainage pathways or skull base neurovascular foramina are affected by the lesion ( Table 43.3 ).

A biopsy is required whenever a diagnosis cannot be established by imaging studies, but it should be avoided when angiofibroma is suspected.14

The use of additional imaging studies, such as positron emission tomography (PET)/CT scan, is indicated only in advanced stages and histologically aggressive (i.e., sinonasal undifferentiated carcinoma, neuroendocrine carcinoma, or high-grade sarcomas) malignant tumors. Ultrasound examination of the neck is included in the preoperative work-up when suspicious nodes are palpable.

Staging systems, which are routinely used for malignant tumors, have been proposed even for benign lesions. Whereas for malignant tumors a committee periodically updates the classification system that is used worldwide, numerous different staging systems have been presented for specific lesions, such as inverted papilloma and juvenile angiofibroma, with the result that none are officially accepted, and consequently comparison of treatment outcomes continues to be problematic. All five staging systems introduced for inverted papilloma15–19 have some limitations, and only the one by Krouse15 ( Table 43.4 ) has gained some popularity. Among the many staging systems reported for juvenile angiofibroma, only those from Andrews et al20 and Radkowski et al21 ( Table 43.5 ) have been extensively used. Interestingly, the most recently introduced system by Snyderman et al22 (see Table 43.5 ) considers the extent of the lesion and also takes into account the absence/presence of vascularity after embolization in advanced tumors.

Malignant tumors are staged according to the seventh edition of the International Union Against Cancer (UICC) classification ( Table 43.6 ), which is applicable to all epithelial and neuroendocrine tumors, but not to soft tissue, bone and cartilage, neuroectodermal, germ cell, and hematolymphoid tumors. For olfactory neuroblastoma, other specific staging systems have been introduced based on extent23,24 or histologic findings.25 The most widely used is the Kadish staging system, as modified by Morita et al26 ( Table 43.7 ).

Patient Selection and Information

Selection of patients who are suitable for endoscopic surgery should be based on factors related to the tumor (histology, extent, and involvement of critical anatomical structures), the patient (concomitant diseases and the patient′s preferences), and the surgeon (specific experience in endoscopic surgery). One of the key issues when planning an endoscopic approach is the identification of the point of origin of the lesion and the adjacent areas involved. Although this information is more easily provided by imaging studies in fibro-osseous lesions, as endoscopic examination is often meaningless, assessment of all the other benign and malignant tumors may benefit from either endoscopic or imaging examination. However, at endoscopy the lesion may fill most of the nasal cavity, thus hampering the assessment of its relationships with adjacent structures even after a thorough decongestion. Furthermore, even high-quality MRI can fail to identify the site of origin of the lesion. This is not the case for juvenile angiofibroma, which invariably has its epicenter of growth at the level of the pterygopalatine fossa, but applies to many osteomas and inverted papillomas, and, in general, to malignant tumors. In recent years, the identification in inverted papilloma at CT of focal hyperostosis or bony strut has been suggested to predict the area of origin of the lesion ( Fig. 43.2 ).27 These features can be detailed even by MRI.28

Most patients with inverted papilloma are nowadays amenable to endoscopic surgery. Only frontal sinus involvement can be a critical issue in the selection process. If a marginal extension of an ethmoid lesion into the frontal or even a frontal lesion originating from the lower part of the sinus can be managed endoscopically, inverted papillomas massively filling the sinus are challenging. Even MRI, in fact, often fails to identify the degree of mucosal involvement. In this specific situation, the actual extent of inverted papilloma can be assessed only at surgery; consequently, the possible need for an extended endoscopic procedure such as a Draf III median sinusotomy or even a combined procedure (transnasal endoscopic in association with a frontal sinusotomy through a coronal osteoplastic approach) should be considered by the surgeon and discussed with the patient. A similar situation is faced when a massive opacification of an extensively pneumatized supraorbital cell of the ethmoid is present.

The indications for endoscopic surgery in juvenile angiofibroma have rapidly evolved so that, at present, the number of patients requiring an external approach is decreasing.29,30 Many authors concur that stage I to IIIA lesions according to Andrews et al20 and stage I to IIC according to Radkowski et al21 can be managed by an endoscopic technique.29–33 Limitations do exist, however, and are mostly related to the relation of the lesion with the internal carotid artery, such as encasement or the presence of extensive afferences ( Fig. 43.3 ) or an extensive growth lateral to the paraclival portion of the vessel. In these situations, an endoscopic assisted anterior (through midfacial degloving) or lateral infratemporal approach is recommended. The possibility to stage the resection to minimize morbidity coming from excessive blood loss should also be considered.29 Recurrent lesions that have evident contact with critical structures, such as the internal carotid artery, optic nerve, cavernous sinus, clivus, and dura of the middle cranial fossa, can be challenging due to scar adhesions coming from previous surgery. In all of these cases, the possible need to intraoperatively switch to a combined procedure should be discussed with the patient.

In general, the indications for surgery in fibro-osseous lesions vary according to the specific histology. In osteoma and fibrous dysplasia, surgery is recommended when the patient is symptomatic or when severe aesthetic deformities are present, whereas in the case of ossifying fibroma resection is always indicated in view of the more aggressive behavior of lesions involving the sinonasal tract compared with mandible localizations. Schick et al34 precisely established indications and limits of endoscopic removal of osteomas. Lesions involving the ethmoid, sphenoid, medial wall of the maxillary sinus, and, in some selected cases, even the inferior and medial wall of the orbit can be transnasally resected. Frontal osteomas are amenable to endoscopic surgery if they are located medial to a virtual sagittal plane through the lamina papyracea ( Fig. 43.4 ) (see Video 25, Draf III for Large Frontal Sinus Osteoma Removed Endoscopically ), if they originate from the inferior portion of the posterior frontal sinus wall, and when the anteroposterior diameter of the frontal sinus is at least 10 mm. Performing a Draf III procedure may sometimes help to resect the lateral part of an osteoma of the frontal infundibulum extending over the orbit. However, in the case of lesions that extend far laterally in a well-pneumatized frontal sinus, radical removal cannot be achieved with a purely endoscopic procedure. Such a lesion can be completely exposed and drilled out by combining an endoscopic approach with an image-guided frontal trephination35 or, in more extensive cases, with osteoplastic flap sinusotomy ( Fig. 43.5 ). The latter technique alone is usually indicated in lesions located far laterally in the sinus or that originate from the anterior wall.

The analysis of criteria for selecting patients with sinonasal malignancies for endoscopic surgery requires some special considerations. The therapeutic strategy should be devised by a multidisciplinary team including surgeons, medical oncologists, radiation oncologists, pathologists, and head and neck radiologists; additionally, the otolaryngologists involved should have a flawless understanding of the biology of the numerous lesions that can be encountered, of basic oncologic principles, and of the role, if any in the specific, of neoadjuvant or nonsurgical treatment. Whenever surgery is planned, it should be performed by a team with experience in endoscopic and external procedures who can cope with the need to modify the surgical strategy according to intraoperative findings. Cooperation with neurosurgeons is obviously required with any patient with a tumor encroaching upon the anterior skull base.

The first experiences in endoscopic resection of sinonasal malignancies were, in general, limited to lesions involving the nasoethmoidal box, but not abutting the anterior skull base ( Fig. 43.6a ). In recent years, indications have been expanded to include tumors eroding the anterior skull base or invading the dura ( Fig. 43.6b–d ).36–38 The major contraindications to performing an exclusively endoscopic removal are nowadays extensive involvement of the brain and the need to extend dura resection well over the orbital roof, which limits the possibility of obtaining an adequate duraplasty ( Fig. 43.7 ). In these cases, as well as in tumors largely involving the frontal sinus, a subfrontal craniotomy needs to be combined (cranioendoscopic approach). Extension to the maxillary sinus walls besides the medial wall, nasal floor, soft tissues of the orbit, and/or lacrimal pathways requires that an external approach be used ( Fig. 43.8 ).

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