Hu JY, He JX, Guo XJ, Zheng XY. Primary colonic malignant peripheral nerve sheath tumor with biphasic morphology: A case report. World J Gastrointest Oncol 2026; 18(10): 123676 [DOI: 10.4251/wjgo.123676]
Corresponding Author of This Article
Xiao-Ying Zheng, MD, PhD, Department of Pathology, The Affiliated Hospital of Qinghai University, No. 29 Tongren Road, Xining 810001, Qinghai Province, China. zxy114289181@qq.com
Research Domain of This Article
Pathology
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case-report
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Hu JY, He JX, Guo XJ, Zheng XY. Primary colonic malignant peripheral nerve sheath tumor with biphasic morphology: A case report. World J Gastrointest Oncol 2026; 18(10): 123676 [DOI: 10.4251/wjgo.123676]
Jia-Yue Hu, Jin-Xu He, Xin-Jian Guo, Xiao-Ying Zheng, Department of Pathology, The Affiliated Hospital of Qinghai University, Xining 810001, Qinghai Province, China
Co-first authors: Jia-Yue Hu and Jin-Xu He.
Author contributions: Hu JY and He JX designed the study, drafted the manuscript, and contributed equally to this work as co-first authors; Zheng XY critically revised the manuscript for important intellectual content; Guo XJ prepared the figures and contributed to visualization; all authors have read and approved the final manuscript.
AI contribution statement: AI tools were used solely for language editing and formatting assistance. No AI tools were used for data analysis, diagnostic interpretation, or scientific decision-making.
Supported by Qinghai Provincial Science and Technology Department's Innovation Platform Development Support Initiative, No. 2024-SF-L01.
Informed consent statement: Written informed consent could not be obtained from the patient's relative due to the remote location. Instead, verbal consent was secured via telephone, following the institutional guidelines for exceptions to written consent. The manuscript has also been fully anonymized. All patient identifiers have been removed, and no name, initials, date of birth, medical record number, or identifiable personal images are included.
Conflict-of-interest statement: The authors report no relevant conflicts of interest for this article.
CARE Checklist (2016) statement: The authors have read the CARE Checklist (2016), and the manuscript was prepared and revised according to the CARE Checklist (2016).
Corresponding author: Xiao-Ying Zheng, MD, PhD, Department of Pathology, The Affiliated Hospital of Qinghai University, No. 29 Tongren Road, Xining 810001, Qinghai Province, China. zxy114289181@qq.com
Received: May 26, 2026 Revised: June 15, 2026 Accepted: June 30, 2026 Published online: October 15, 2026 Processing time: 119 Days and 2.1 Hours
Abstract
BACKGROUND
Malignant peripheral nerve sheath tumor (MPNST) is a rare and highly aggressive soft tissue sarcoma, in which primary colonic involvement is exceptionally uncommon. Previously reported colonic cases have mostly shown a conventional spindle-cell morphology, while cases with unusual histologic patterns remain poorly characterized.
CASE SUMMARY
In the reported case, a 75-year-old man presented with intermittent right upper abdominal pain and abdominal distension. He underwent contrast-enhanced computed tomography, which revealed a large invasive mass extending from the right subphrenic region to the gallbladder fossa, with indistinct borders from the adjacent liver, duodenum, and pancreatic head. Exploratory laparotomy and right hemicolectomy were performed. Histologically, the tumor displayed a biphasic pattern composed of approximately a 30% spindle-cell component and 70% small round-cell component. The spindle-cell areas consisted of intersecting fascicles of atypical spindle cells with hyperchromatic nuclei and brisk mitotic activity, while the small round-cell areas were composed of densely packed primitive-looking cells with scant cytoplasm and hyperchromatic nuclei. Tumor necrosis was also observed. Immunohistochemically, S-100 showed patchy positivity in approximately 40% of tumor cells, while cytokeratins, smooth muscle markers, melanocytic markers, and Ewing sarcoma-related markers were negative. The Ki-67 Labeling index was very high, at approximately 90%, and a complete loss of H3K27me3 was observed in all the tumor cell nuclei. Based on the morphologic features, immunophenotype, and exclusion of major differential diagnoses, the lesion was diagnosed as a primary sporadic high-grade MPNST of the colon. Despite complete resection of the tumor with negative margins, the patient rapidly developed massive pleural and peritoneal effusions after surgery, which then progressed to respiratory failure, and he ultimately died on postoperative day 13.
CONCLUSION
Primary colonic MPNST may present with an atypical biphasic spindle and small round cell morphology, creating a potential diagnostic overlap with other high-grade mesenchymal malignancies of the colon. In challenging cases, a consideration of the H3K27me3 status may provide important ancillary diagnostic support. Even after complete resection, tumors with high-risk pathologic features may follow an extremely aggressive clinical course, underscoring the need for early recognition, accurate pathologic diagnosis, close postoperative surveillance, and multidisciplinary management.
Core Tip: Primary malignant peripheral nerve sheath tumor of the colon is exceptionally rare. We report a sporadic colonic case with unusual biphasic spindle and small round cell morphology, complete loss of H3K27me3, and an extremely aggressive postoperative course despite R0 resection. This case highlights the diagnostic difficulty of high-grade mesenchymal malignancies of the colon and underscores the importance of integrating morphology, immunohistochemistry, and H3K27me3 status for accurate diagnosis, as well as the need for close postoperative surveillance.
