Introduction: Nodular fasciitis (NF) is a benign, rapidly proliferating fibroblastic lesion that may show 18F-fluorodeoxyglucose (FDG) uptake on PET/CT, often mimicking malignancy. Postoperative intra-abdominal NF following colorectal cancer surgery is extremely rare.
Case presentation: A 56-year-old man underwent endoscopic mucosal resection for sigmoid colon cancer, followed by laparoscopic sigmoidectomy for submucosal invasive carcinoma (pT1b). Twelve months later, CT revealed a 13-mm mass near the superior rectal artery, and PET/CT showed mild FDG uptake (maximum standardized uptake value 1.13). Laparoscopic excision was performed, and histopathology confirmed NF. No recurrence has been observed after 3 years.
Conclusions: Intra-abdominal NF may closely resemble lymph node recurrence after colorectal cancer surgery. Clinicians should consider NF in the differential diagnosis of postoperative intra-abdominal nodules with FDG uptake.
Keywords: colorectal cancer; intra-abdominal lesion; nodular fasciitis.
© 2026 The Author(s). Published by Japan Surgical Society.