Small intestinal SMARCA4-deficient undifferentiated carcinoma with intussusception: A case report

Switch/sucrose non-fermentable (SWI/SNF) related matrix associated actin-dependent regulator of chromatin sub-family A member 4-deficient undifferentiated carcinoma (SMARCA4-DUC) of the small intestine is a rare and highly aggressive subtype of gastrointestinal malignancy. The present study reported the case of SMARCA4-DUC in a patient who presented with intestinal intussusception and multi-organ metastasis to the lungs, liver, spleen and skin, which led to rapid progression and death in 43 days. The present case highlighted the unique histological and molecular features of SMARCA4-DUC, characterized by the absence of SMARCA4 expression and undifferentiated cellular morphology. The present case report aimed to describe the clinical presentation, imaging findings, pathological features and treatment course, to further the current understanding of SMARCA4-associated malignancies and improve the recognition of SMARCA4-DUC among clinicians and pathologists. Next-generation sequencing of the primary small intestinal tumor identified pathogenic mutations in PTEN, TP53, ataxia telangiectasia mutated, ephrin type-A receptor 5 and EGFR p.F997L, suggesting a DNA-repair-deficient genomic background and providing potential targets for future precision therapy. Further research is warranted to determine the molecular mechanisms underlying SMARCA4-DUC, for the development of targeted therapeutic strategies and to improve the understanding of the aggressiveness of SMARCA4-DUC.