Radiological features of desmoid-type fibromatosis: a two-institution retrospective study.

OBJECTIVES

To characterize the radiological findings of desmoid-type fibromatosis (DF).

METHODS

This two-institution retrospective study included 152 patients with pathologically confirmed DF who underwent computed tomography (CT), magnetic resonance imaging (MRI), or 18F-fluorodeoxyglucose-positron emission tomography (FDG-PET)/CT between January 2001 and February 2024. Two board-certified radiologists independently evaluated the CT, MRI, and FDG-PET/CT findings, and a third board-certified radiologist resolved discrepancies. Imaging was performed with and without contrast media: 70 patients underwent plain CT, 95 underwent contrast-enhanced (CE) CT, 115 patients underwent plain MRI examinations, 100 patients underwent CE-MRI, and 11 patients underwent FDG-PET/CT (most patients underwent several modalities).

RESULTS

The median age of the patients was 40 years, with a female predominance (male, 39.5% vs female, 60.5%). Swelling or palpable mass was the most frequent symptom (78/152, 51.3%). Gross total resection of DF was performed in 57 patients, with a recurrence rate of 38.6% (22/57). Tumors were most frequently observed in the extra-abdominal region (79/152, 51.6%). Characteristic radiological features included intermediate intensity on T2-weighted imaging (112/113, 99.1%), intermediate-to-high intensity on T1-weighted imaging (109/111, 98.2%), substantial enhancement in the late phase on MRI (100/100, 100%), moderate to strong enhancement in the late phase on CT (18/20, 90%), and arterial penetration sign on CE-CT (25/96, 26.0%). The mean apparent diffusion coefficient (ADC) of DFs was 1.46 × 10 mm/s (range, 1.00-2.20).

CONCLUSION

This study highlights the unique imaging features of DF, including the arterial penetration sign and high mean ADC values, which can aid in differentiating DF from other soft tissue tumors. These findings may improve preoperative diagnostic accuracy and reduce the need for invasive procedures.

KEY POINTS

Question Imaging findings of DF are not well-documented in large-scale studies. Findings This study identifies unique imaging features of DF, such as the arterial penetration sign and high mean ADC values. Clinical relevance These distinctive imaging characteristics improve diagnostic accuracy for DF and lead to appropriate patient management, as DF requires distinct treatment strategies.