Distinct multiplex immunofluorescence-based immune and stromal marker expression profile of subcutaneously metastatic SMARCA4-deficient undifferentiated thoracic tumor: a case report

The SMARCA4 gene encodes the BRG1 protein, a key component of the switch (SWI)/sucrose nonfermenting (SNF) chromatin remodeling complex, and its loss has been implicated in the pathogenesis of various tumors. SMARCA4-deficient undifferentiated thoracic tumor (SMARCA4-UT) is a rare, rapidly progressive, and highly aggressive subtype that is associated with a poor prognosis, with subcutaneous metastasis being one of its uncommon distant-spread phenotypes. The tumor microenvironment (TME) of SMARCA4-UT is closely associated with tumor metastasis and immunotherapeutic response, but the expression profiles of key immune and stromal markers in subcutaneous metastatic lesions have not been clarified.