The Desmoid Tumor Research Foundation

April 2026

Desmoid Fibromatosis of the Gastric Wall Mimicking Needle Tract Seeding after Endoscopic Ultrasound-Guided Fine-Needle Biopsy for Pancreatic Cancer: A Case Report

Author Information

Kazuya Koyama 1, Kenji Takahashi 1 2, Hidemasa Kawabata 1, Yusuke Ono 1 2 3, Nobue Tamamura 1, Tetsuhiro Okada 1, Hidetaka Iwamoto 1, Mishie Tanino 4, Mikihiro Fujiya 1, Yusuke Mizukami 1 2 3

1Department of Internal Medicine Division of Gastroenterology Asahikawa Medical University Hokkaido Japan. 2Center For Intractable Diseases and ImmunoGenomics National Institutes of Biomedical Innovation Health and Nutrition Osaka Japan. 3Institute of Biomedical Research Sapporo Higashi Tokushukai Hospital Hokkaido Japan. 4Department of Diagnostic Pathology Asahikawa Medical University Hospital Hokkaido Japan.

Publication

DEN Open

Summary

Endoscopic ultrasound-guided fine-needle biopsy (EUS-FNB) is widely used for the pathological diagnosis of pancreatic diseases. However, needle tract seeding (NTS) remains a clinical concern, particularly when the puncture route is not included in the surgical resection field. We report a case in which distinguishing NTS from other pathologies was challenging. A woman in her 70s underwent EUS-FNB via the gastric antrum for a 10-mm pancreatic head lesion, which was diagnosed as adenocarcinoma (cT1bN0M0, Stage IA). She subsequently underwent pancreaticoduodenectomy (pT3N0M0, Stage IIA) without adjuvant chemotherapy. Two years postoperatively, a 30-mm submucosal tumor was detected in the stomach. Although positron emission tomography-computed tomography demonstrated fluorodeoxyglucose uptake, three separate sessions of EUS-FNB failed to yield a definitive diagnosis, with NTS being strongly suspected. Partial gastrectomy was performed. Histopathology revealed a fascicular proliferation of spindle-shaped cells with nuclear β-catenin positivity, leading to the diagnosis of a desmoid fibromatosis (DF). This case underscores that although NTS should be considered when a lesion arises along the EUS-FNB puncture tract, alternative diagnoses, including DF, must also be carefully evaluated.

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