xRead - Nasal Obstruction (September 2024) Full Articles

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167

ICAR SINONASAL TUMORS

mean follow-up time of 28 months, the nasal cavity was the primary tumor location in 66.7% of cases, with two thirds arising from the middle turbinate. 852 Other sites of nasal origin include the superior and inferior turbinates, the lateral nasal wall, and the nasal septum. 853–855 Tumors arising from the paranasal sinuses were most commonly situated in the ethmoid cavity. The most common present ing symptoms included recurrent epistaxis (68.5%), nasal obstruction (53.7%), and headache (13.0%). Macroscopically, tumors are often firm and encapsu lated. Histologically, paragangliomas need to be differ entiated from other neuroendocrine neoplasms. Paragan gliomas are positive for chromogranin, synaptophysin, and neuron-specific enolase, but negative for cytokeratin. The associated sustentacular cells will stain for S100. Tumors classically consist of individual tumor cells with round nuclei (chief cells) arranged in nests—the characteris tic “zellballen” architecture—surrounded by sustentacular cells and divided by vascular stroma. 856–859 Up to 50% of head and neck paragangliomas are associated with a genetic syndrome, most commonly mutations in the genes for succinate dehydrogenase subunits. In particular, SDHB mutations are associated with extra-adrenal tumors and have an increased risk of malignant and recurrent lesions. 851,856 In one systematic review, of the studies reporting tumor pathology, 71.4% were designated as benign lesions and 28.6% diagnosed as malignant paraganglioma. 852 The dis tinction between benign and malignant entities is con troversial. Consequently, diagnosis of malignant paragan glioma is often made on clinical evidence of aggressive behavior including regional spread to lymph nodes or distant metastasis to nonneuroendocrine tissue. 852,860–865 Functional paragangliomas have been estimated to rep resent 1%–3% of all cases in the head and neck, though a recent systematic review of sinonasal lesions noted an inci dence of 7.4% with tumors secreting adrenocorticotropic hormone (ACTH) or catecholamines. 849,851,852,866–869 Eval uation for biochemical abnormalities is indicated in para gangliomas, particularly in symptomatic patients, and is critically important in cases of catecholamine-secreting tumors where surgical intervention without appropriate adrenergic blockade may be catastrophic. 851,866 CT imaging, though less specific than MRI, is useful for surgical planning and for evaluating bone involvement. 852 On MRI, paragangliomas demonstrate high signal on T2 sequences and low signal on T1-weighted imaging, with the classic “salt and pepper” appearance resulting from hyperintense foci interspersed with areas of signal void related to high-flow vascular channels. 869 Tumors enhance with contrast on both CT and MRI. Nuclear imaging such as metaiodobenzylguanidine ([ 123 I]MIBG) or indium [ 111 In]DTPA-octreotide SPECT scintigraphy—

particularly in cases with a genetic predisposition—can help determine the extent of the tumor and detect syn chronous lesions. 870,871 PET/CT imaging is a more efficient and sensitive means of imaging paragangliomas com pared to scintigraphy. 869 In particular, 18 F-FDG or [68Ga DOTA]-TATE PET imaging is used to assess locoregional extension, multifocality, and metastases, while the lat ter is particularly useful in detecting functional tumors producing ACTH. 849,851,867,871,872 Surgery is the first-line treatment for sinonasal para gangliomas. The optimal approach—open, endoscopic, or combined—should be made with the goal of achiev ing complete resection through optimal exposure while limiting morbidity. More recent case reports have demon strated a trend toward endoscopic approaches for resection of these lesions, though open approaches are also effec tive. Indeed, in a systematic review of published cases, an open approach was employed in 63% of cases, an endoscopic approach in 33.3%, and a combined approach in 3.7%. 852 Preoperative angiography and embolization should be strongly considered given the rich vascularity of paragangliomas. 851,873 The use of advanced technology, such as radiofrequency coblation, can facilitate hemosta sis during dissection. 874 While chemotherapy is largely ineffective, RT has been used to successfully halt the growth of disease, particularly in patients with unre sectable disease or who cannot tolerate surgery. 851,872,875 Estimation of long-term prognosis is dependent on system atic reviews incorporating case series indicating that most (63%) of patients were disease free at a mean follow-up of 24.6 months. Recurrence rate was 21.7% between 12 and 156 months after initial resection. Metastasis was reported in 8.7% of cases. 852 Table XVII.B.2 summarizes evidence surrounding paraganglioma. Aggregate grade of evidence : C (Level 2: one study; Level 3: 10 studies)

XVIII

CONGENITAL MIDLINE NASAL

MASSES A Introduction

CMNMs are relatively rare midline nasal lesions, and are estimated to occur in about 1:20,000–1:40,000 births. 877 They arise from failure of embryological separation of neuroectodermal and ectodermal tissue, which can lead to intranasal and extranasal masses. 878–880 Even though most are diagnosed at birth or childhood, rarely they may not be recognized until adulthood and require a high level of suspicion. 881 The most common CMNMs are nasal dermoid cysts, nasal gliomas, and meningoceles/encephaloceles. 882 These lesions may