IPMN high-risk stigmata: sensitive, but one in three benign lesions flagged

Design

Single-centre retrospective diagnostic study

Population

418 surgically confirmed IPMNs, 173 malignant

Primary outcome

Accuracy of MRI high-risk stigmata for malignancy

Effect

Sensitivity 82.7% (95% CI 76.2–88.0); specificity 66.9% (60.7–72.8)

This single-centre retrospective study reviewed preoperative MRI in 418 surgically confirmed intraductal papillary mucinous neoplasms resected between 2011 and 2023, of which 173 were malignant, against the international guideline's high-risk stigmata.

The current stigmata had 82.7% sensitivity and 66.9% specificity for malignancy. Obstructive jaundice and suspicious cytology were almost perfectly specific; an enhancing mural nodule of 5 mm or more and a main duct of 10 mm or more were the weaker features (specificity about 80%). Raising the cutoffs — for example to a 12 mm nodule and 12 mm duct — increased specificity to 82% but cut sensitivity to 65%. The combined score's AUC rose modestly, from 0.77 to about 0.80.

For reporting, the useful message is that the size-based stigmata drive the false positives. Stating measured nodule size and duct calibre precisely, rather than only whether a threshold is crossed, helps the surgical team weigh resection. The guideline thresholds have not changed, and a single surgical series overrepresents lesions that looked worrying enough to resect.

• Report the measured enhancing nodule size and main duct diameter, not only whether a stigma is present.
• Highlight jaundice-related findings and positive cytology, which were nearly always malignant.
• Expect about one in three resected lesions meeting current stigmata to be benign.
• Continue to apply current guideline thresholds; they have not changed on this study.
• Discuss borderline nodule and duct sizes at the pancreatic multidisciplinary meeting.

Why it matters

It locates the source of unnecessary pancreatic surgery in two measurements radiologists already make.

Don't overread it

This is a single-centre surgical series; the adjusted cutoffs are not validated and guideline thresholds stand.

The statistics, in plain English

Specificity of 67% means a third of benign lesions met high-risk criteria. Raising cutoffs trades missed cancers for fewer unnecessary operations. Because only resected lesions were studied, the true false-positive rate across all IPMNs on MRI may differ.

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