xRead - Nasal Obstruction (September 2024) Full Articles

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ICAR SINONASAL TUMORS

and less than 1% of melanomas. Of mucosal melanomas arising in the head and neck region, 60%–70% arise in the nasal cavity and paranasal sinuses. 12,391,1475–1477 Whenaris ing in the sinonasal cavity, the anatomic site of origin is most commonly the nasal cavity (70%), following by the maxillary sinus (13%) and ethmoid sinus (6%). 366 SNMM is considered and managed as a distinct entity from cuta neous melanoma; its incidence has been increasing since 1960. 1478 It is noncutaneous and arises from melanocytes within the sinonasal mucosa. Moreover, SNMM has a distinct pattern of tumorigenesis, genetic mutational land scape, and molecular profile compared to cutaneous melanoma, with essentially no UV light mutational signa ture within its genetic mutational landscape. 366,1479-1481 Survival and prognostic factors SNMM is a uniquely aggressive neoplasm with poor survival. The reported 5-year OS for all patients is 22%– 28%. 1477,1482,1483 With localized disease only (N0), the reported 5-year OS is 25%. However, when regional lymph node metastases are present (N + ) at the time of diag nosis, the 5-year OS is reduced to 3.9% or less. 1482,1483 In contrast, the 5-year OS for cutaneous melanoma with localized disease is > 95%. 1484 Recurrence after treatment is common with local recurrence in 18%–46%, regional recurrence in 11%–18%, and distant metastases in 35% of patients. 269,1485,1486 This poor survival is reflected in the AJCC’s unique stag ing system for SNMM. 391,1484,1487 In this system, SNMM T-stage is limited to T3 and T4 disease, effectively indi cating that each presenting tumor is a minimum of Stage III. However, as compared to most head and neck malig nancies in which clinical staging is highly correlated with survival, SNMM staging has been shown to poorly corre late with prognosis. 1487,1488 It should be noted that current AJCC staging for SNMM does not include any histopatho logic or proliferative factors, in contrast to staging of cutaneous melanoma. Several prognostic factors have been shown to be associ ated with SNMM survival. Evaluations of pooled data from the SEER and NCDB have shown that primary SNMM of the nasal cavity has improved survival compared to the paranasal sinuses. In addition, older age, positive nodal status, distant metastases, and increased tumor volume have also been associated with worsened OS. 391,1483,1489–1491 2 Histopathologic findings The histopathologic hallmark of SNMM is intraepithe lial melanocytic proliferation and atypia. Select tumors 1

may demonstrate spindled, epithelioid, or small cell morphology. 391,1492,1493 Satellite or skip mucosal lesions are also common in 26% of patients and have been shown to be associated with worsened rates of local control. 1494 Classic histopathologic markers of SNMM include S100, SOX10, and HMB45. 1493,1495 The presence of brisk TILs has been associated with improved RFS. Additionally, patients with amelanotic lesions are more likely to present with higher stage tumors and less likely to have brisk TILs and worsened RFS. 1481,1496 Higher Ki67 and mitotic rate indices have also been associated with worsened 5-year OS and RFS. 1481,1496–1498 Patients on immunotherapy with a Ki67 of < 40% have been shown to have improved 3-year OS compared to those with higher Ki67. 1481 3 Surgical resection Following the treatment paradigm of cutaneous melanoma as well as the majority of SNM, surgical resection remains the primary treatment modality for SNMM tumors that are resectable (Table XXIV.D.1). 269,278,366,1483,1499–1501 Complete tumor resection with negative margins is the goal of sur gical intervention, including resection of all skip lesions when present. 1499,1501 In several institutional series and large database studies, surgical resection with negative margins has been associ ated with improved OS and RFS 1502 compared to surgery with positive margins or no surgery at all. 360,365,366,1503,1504 In an NCDB study of 1874 SNMM patients, surgical resec tion with negative margins was associated with improved OS; however, resection with positive margins was not independently associated with worse OS. 1502 Another population-based analysis of 446 SNMM patients found that a negative-margin surgical resection was associ ated with improved OS compared to a positive-margin surgical resection; there was no difference in OS for patients who underwent a positive-margin surgical resec tion and no surgery at all. 365 Another study of 1373 patients with head and neck mucosal melanoma (79% of which were sinonasal) found that undergoing surgery (HR0.45; p < 0.001) and obtaining negative margins (HR 0.52; p < 0.001) were both associated with improved sur vival, even after controlling for tumor size, stage, and comorbidities. 1503 Although the majority of literature sup ports a negative margin surgical resection to improve OS, one institutional study of 72 patients undergoing surgery for SNMM found that no particular surgical factor was associated with OS including margin status, tumor stage, or surgical approach utilized. 271 The selection of surgical technique is largely based upon surgeon expertise, tumor extent, and ability to achieve negative margins. 1499,1501,1505–1507 Traditionally,