An Evolving and Rare Entity: SMARCB1(INI-1)-Deficient Sinonasal Carcinoma

Authors : Nuket Özkavruk Eliyatkın, Zehra Ecem Ertepe Özer, Nezahat Erdoğan, Erdem Eren, Zeynep Güç

Pages : 497-503

Doi:10.20515/otd.1583994

View : 30 | Download : 14

Publication Date : 2025-05-02

Article Type : Other Papers

Abstract :Malignant tumors of the paranasal sinuses and nasal cavity are rare. These tumors constitute very few of all head and neck tumors. With the developments in the field of molecular biotechnology, significant revisions have been made in The 2022 5th edition of the WHO Classification of the Head and Neck. Tumors with the definition of new entities. SWItch/Sucrose Non-Fermentable (SWI/SNF) complex-deficient carcinomas, which have been included as a separate entity under the general heading of sinonasal undifferentiated carcinomas, consist of two major subtypes caused by the loss of one of the SWI/SNF complex genes; SMARCB1-deficient sinonasal carcinoma and SMARCA4-deficient sinonasal carcinoma. The most common subtype is SMARCB1-deficient sinonasal carcinoma. These tumors have been misdiagnosed as neuroendocrine carcinoma, poorly differentiated carcinoma, sinonasal undifferentiated carcinoma and teratocarcinoma in previous years according to our current knowledge. Histopathologically, uniform cytologic features and appearance mimicking many tumors make it difficult to diagnose especially in small biopsies. Correctly naming this high-grade malignancy within the scope of molecular classification is important for treatment planning. Optimal treatment approaches are also limited. Although there is a consensus on radical resection/surgery followed by adjuvant treatment, the order of treatment may vary between institutions. Agents such as immune checkpoint inhibitors and EZH2 inhibitors are among the new treatment options. In this report, we present a case of SMARCB1-deficient sinonasal carcinoma according to the new molecular classification with recurrence at the age of 20. We aimed to emphasize the importance of histopathological and immunohistochemical findings and to raise awareness of the presence of this entity.
Keywords : Sinonasal carcinoma, SMARCB1, INI-1, SMARCB1 (INI-1) deficient, sinonasal undifferentiated carcinoma

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