Extrathoracic SMARCA4-deficient tumors:clinicopathological features and review of literature

HU Xiaoxue; WANG Lei; ZHANG Yaping; WANG Bixi; YANG Jiajia

doi:10.3969/j.issn.1007-8096.2026.01.016

Abstract：Objective To improve the diagnostic level of extrathoracic SMARCA4-deficient tumors by summarizing and analyzing the clinicopathological features of cases of extrathoracic SMARCA4-deficient tumors and relevant reports in the databases.Methods Five cases of extrathoracic SMARCA4-deficient tumors diagnosed and treated in our hospital from 2023 to 2024,as well as primary extrathoracic SMARCA4-deficient tumor cases reported in China National Knowledge Infrastructure(CNKI)and PubMed databases during the same period,were retrospectively analyzed.The clinicopathological features,diagnosis and differential diagnosis,clinical treatment and prognosis of the above cases were summarized and analyzed.Results In addition to recurrent and metastatic SMARCA4-deficient tumors,primary extrathoracic SMARCA4-deficient tumors occurred in multiple systems throughout the body,predominantly in middle-aged and elderly male patients.These tumors progressed rapidly,were prone to recurrence,and lacked effective treatment modalities.Microscopically,the tumor cells exhibited significant atypia with frequent mitotic figures,showing undifferentiated epithelioid and rhabdoid morphology,reduced intercellular adhesion,and occasional collagen degeneration and coagulative necrosis.Immunohistochemically,CKpan was often weakly positive and SMARCA4 was negative,while molecular testing provided additional diagnostic value.Conclusion Extrathoracic SMARCA4-deficient tumors are highly malignant,prone to recurrence and metastasis,and can occur in multiple sites throughout the body.The characteristic rhabdoid morphology and reduced intercellular adhesion under microscope are suggestive,and the diagnosis can be confirmed by combining immunohistochemistry with molecular testing.