xRead - Nasal Obstruction (September 2024) Full Articles

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may be identified. While this appears similar to ACC, PNI is uncommon. While these tumors stain p16 positive, the staining pattern is different from that of oropharyngeal HPV-associated tumors. This tumor tends to demonstrate an indolent course compared to aggressive sinonasal carci nomas, such as SCC. The largest study to date includes 49 patients and demonstrates a failure rate of 36%, primarily recurring locally. Only rare cases cause distant disease. Primary treatment is surgical resection, with the possi bility of adjuvant radiation if there is concern regarding the adequacy of the surgical margins or in the setting of recurrence. 1071 c Primary site SNSCC does not affect all subsites within the sinonasal tract equally. In a review of 5567 SNSCC patients from the SEER database between 1973 and 2011, Dutta et al. noted SNSCC to most commonly originate from the nasal cavity (46.5%), followed by the maxillary sinus (40.2%), ethmoid sinus (5.6%), sphenoid sinus (2.3%), and then the frontal sinus (1.1%). In this review, it was noted that 4.1% of SNSCC originated in an accessory sinus or from overlapping subsites. 29 However, other reports suggest that the maxillary sinus is in fact the most common site affected by SNSCC (60%), followed by the nasal cavity (25%) and the ethmoidal complex (15%). 1070 The reason for this disagreement is unclear. Nonetheless, the site of origin is an important distinc tion, as the clinical behavior and prognosis of SNSCC arising from the maxillary sinus are different from those arising from the nasoethmoidal complex. Dutta et al. report a 52.3% 5-year DFS for SNSCC. However, this ranges from 30.5% when the site of origin is the frontal sinus to 34.1% when the site of origin is the maxillary sinus, and up to 76.0% when the site of origin is the nasal cavity. 29 Because of this, as is described below, the “T” definitions within the TNM staging system vary by tumor subsite. Additionally, though cervical lymph node metastasis is uncommon overall for SNSCC, a maxillary site of ori gin is much more likely to present with nodal metastasis than nasoethmoidal SNSCC. Cervical metastases, when present, confer worse prognosis. 231,1063 d Biomarkers While the diagnosis of these subtypes often relies on his tologic features, there has been recent interest in novel biomarkers as a means of diagnostic, prognostic, and ther apeutic intervention. The diagnosis of poorly differentiated SNSCC is challenging, as the differential is broad, includ ing SNUC, SNEC, and subtypes of SNUC. The use of IHC and genomic analysis may help aid tumor characteriza tion (i.e., SMARCA4 , SMARCB1 , IDH2 , NUTM1 pathogenic variants). Additionally, the use of biomarkers in defining

tumor cell lines has demonstrated that de novo SNSCC and IP-associated SNSCC are biologically distinct entities. Further, EGFR, p53, TrkB, and programmed death-ligand 1 (PD-L1) have been identified in SNSCC, offering possible targets for therapeutic intervention. 111 3 Staging and imaging Appropriate pretreatment staging of SNSCC is critical. Staging of SNSCC follows the same staging system as all other primary epithelial sinonasal tumors as defined by the AJCC 8th edition. 158 Unlike SCC of other sites in the head and neck, in which TNM stage is often defined by size, “T” stage of SNSCC is defined by location of origin and extent of involvement and invasion of local structures. To that end, high-quality cross-sectional imaging is criti cal to properly assess the degree of local extension with attention to the skull base, orbit, PPF, ITF, and parapharyn geal space. The gold standard imaging modalities include both CT and MRI. SNSCC can extend to adjacent struc tures via transgressing bony barriers of the nasal cavity, paranasal sinuses, orbit, and skull base. Erosion or reab sorption of these bony structures is best demonstrated on CT. Gadolinium-enhanced MRI offers great soft tissue res olution and provides better structural imaging than CT. MRI is useful for detecting invasion of nearby soft tis sues including periosteum/periorbita, orbit, dura, brain, and cavernous sinus. Finally, like for SCC at other sites of the head and neck, PET/CT can offer essential stag ing information for advanced SNSCC. PET/CT can provide simultaneous anatomical and metabolic data of the pri mary tumor, while identifying both regional and distant metastasis. Role of induction/neoadjuvant chemotherapy There is currently no consensus on the role of neoadjuvant chemotherapy for SNSCC. Data for outcomes of neoad juvant chemotherapy are limited due to the rarity of the disease and because most phase III head and neck SCC studies excluded patients with sinonasal cancer. Current treatment regimens are largely extrapolated from more common tumors in other subsites of the head and neck. 1072 A recent Triological Society Best Practices article reviewed this topic and identified several studies supporting treat ment of locally advanced SNSCC with potential for organ preservation, suggesting its utility in the management algorithm. 1073 One of the earliest studies evaluating the role of neoad juvant chemotherapy in the treatment of SNSCC was 4 Treatment and outcomes a