PANCREATIC acinar cell carcinoma (PACC) imaging could help clinicians distinguish this rare pancreatic tumour from other pancreatic neoplasms while also identifying patients at greater risk of postoperative recurrence, according to a multicentre retrospective study.
PACC is a rare form of pancreatic cancer that can resemble other pancreatic tumours on imaging, making diagnosis challenging. Researchers identified three distinct morphological imaging subtypes, finding that larger lesions and an infiltrative pattern independently linked to postoperative recurrence following curative resection.
The study included 36 patients with pathologically confirmed PACC who underwent CT or MRI between 2008 and 2024. Investigators classified the tumours into three imaging phenotypes: a well-demarcated solid mass (Type 1), a predominantly intraductal mass (Type 2), and an indistinct infiltrative mass (Type 3).
Across the cohort, 76.7% of tumours showed marked diffusion restriction, 52.8% demonstrated lobulated internal architecture, and 80.6% had minimal intratumoral necrosis.
Type 1 was the most common subtype (n=19), followed by Type 2 (n=8) and Type 3 (n=9). Type 1 tumours were larger than the other subtypes, with a median maximal size of 6.3 cm compared with 3.0 cm for Type 2 and 2.5 cm for Type 3 (p=0.002). They also more frequently demonstrated venous thrombosis (31.6% versus 0% for both other subtypes; p=0.040) and lobulated internal architecture (78.9% versus 37.5% and 11.1%, respectively; p=0.002).
Among the 28 patients who underwent curative resection, multivariable analysis identified maximal tumour size and the Type 3 infiltrative subtype as independent predictors of recurrence.
Each increase in maximal tumour size was linked to a higher recurrence risk (HR 1.7; 95% CI 1.2–2.3). Patients with Type 3 tumours were also significantly more likely to experience recurrence after curative resection (HR 7.7; 95% CI 1.1–53.6).
The findings suggest that recognising characteristic imaging phenotypes may help radiologists distinguish PACC from more common pancreatic tumours while identifying patients at increased risk of postoperative recurrence. Tumour size and the infiltrative subtype could therefore serve as imaging biomarkers to inform postoperative risk assessment.
Hwang JA et al. Imaging phenotypes of pancreatic acinar cell carcinoma: a multicenter study of morphologic subtypes and recurrence. Eur Radiol. 2026;DOI:10.1007/s00330-026-12776-1.
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