Clinicopathologic characteristics of malignant rhabdomyoma of digestive tract in adults

FENG Lian; TANG Hong-qun; LI Dan-gui

doi:10.3969/j.issn.1007-8096.2025.05.016

Abstract：Objective To investigate the clinicopathological features,diagnosis,differential diagnosis,and treatment of malignant rhabdoid tumor(MRT),along with a literature review.Methods The clinical data of a 77-year-old female patient diagnosed with MRT of the digestive tract at the Department of Pathology,Yudu County People's Hospital,were retrospectively analyzed.Hematoxylin-eosin(HE)staining,immunohistochemical EnVision two-step staining,and fluorescence in situ hybridization(FISH)were performed.Relevant literature was reviewed.Results The patient,a 77-year-old female,was admitted due to abdominal pain lasting one month.CT findings indicated circumferential wall thickening of the ileocecal region with luminal stenosis,blurred surrounding fat planes,and multiple enlarged lymph nodes near the right psoas muscle,suggesting a possible tumor and necessitating further examination.Colonoscopy revealed an ulcerative mass at 65 cm from the anal verge in the ascending colon,with a fragile texture and easy bleeding upon contact.The lesion occupied nearly the entire lumen,obstructing endoscopic passage,raising suspicion for ascending colon carcinoma.Pathological biopsy demonstrated tumor cells arranged in sheets or nests,composed of large round or polygonal cells with loose architecture and poor cohesion.The nuclei were large,round to oval,eccentrically located,and vesicular,with frequent mitotic figures.The cytoplasm was abundant and eosinophilic,with extensive necrosis in the stroma.Immunophenotyping showed the following:CK(paranuclear globular+),Vimentin(paranuclear globular+),SMARCA4(nuclear+),CAM5.2(focal paranuclear dot-like+),Ki-67(40%nuclear+),INI1(negative in tumor cells,positive in lymphoid and endothelial cells as internal control),and S100(focal cytoplasmic+).Other markers,including CD34,CD20,CD3,SALL4,Desmin,CD31,EMA,HMB45,MyoD1,Caldesmon,ALK,CD30,and CD43,were negative.FISH analysis revealed no SMARCB1(22q11)gene deletion.Conclusion Malignant rhabdoid tumor(MRT)is a highly aggressive malignancy.Due to its extreme rarity,diagnosis requires a combination of histomorphology,immunophenotype,and molecular testing to avoid misdiagnosis or missed diagnosis.