Widespread and multifocal carcinomas in situ (CISs) through almost the entire pancreas: report of a case with preoperative cytological diagnosis

High signal intensity on diffusion-weighted magnetic resonance images is a useful finding for detecting early-stage pancreatic cancer

Purpose

Early detection of pancreatic ductal adenocarcinoma (PDAC) may improve the prognosis. We evaluated novel imaging findings that may contribute to early detection.

Methods

This single-center, retrospective study enrolled 37 patients with a localized main pancreatic duct (MPD) stricture and no obvious pancreatic mass. All patients underwent endoscopic retrograde cholangiopancreatography and brush sampling with cytology and serial pancreatic juice aspiration cytologic examination via endoscopic naso-pancreatic drainage. Patients with cytology-confirmed malignancy underwent surgical resection. The remaining patients were followed by contrast-enhanced computed tomography (CECT), magnetic resonance imaging (MRI), and endoscopic retrograde cholangiopancreatography.

Results

Twenty patients had confirmed malignancy (cancer group) and 17 did not (non-cancer group). Age, MPD stricture location, and PDAC risk factors were similar, but the sex predominance and symptom rate differed between the two groups. In the cancer group, 17 patients were diagnosed by cytology and three by clinical symptoms. CECT, MRI, and endoscopic ultrasonography (EUS) revealed no solid tumors in either group. CECT revealed no significant differences between groups. Diffusion-weighted MRI revealed significant differences in the signal intensity between groups. EUS detected indistinct and small hypoechoic areas in 70% and 41.2% of patients in the cancer and non-cancer groups, respectively. In the cancer group, 11 were diagnosed with cancer at the first indication, and nine were diagnosed at follow-up; the prognosis did not differ between these two subgroups.ss

Conclusions

High signal intensity in diffusion-weighted MRI may be useful for detecting early-stage PDAC and may be an indication for surgical resection even without pathologic confirmation.

Clinical trial registration

The study was a registered at the University Hospital Medical Information Network (UMIN000039623).

Graphic abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s00261-021-03199-1.

A Revised Classification System and Recommendations From the Baltimore Consensus Meeting for Neoplastic Precursor Lesions in the Pancreas

International experts met to discuss recent advances and to revise the 2004 recommendations for assessing and reporting precursor lesions to invasive carcinomas of the pancreas, including pancreatic intraepithelial neoplasia (PanIN), intraductal papillary mucinous neoplasm (IPMN), mucinous cystic neoplasm, and other lesions. Consensus recommendations include the following: (1) To improve concordance and to align with practical consequences, a 2-tiered system (low vs. high grade) is proposed for all precursor lesions, with the provision that the current PanIN-2 and neoplasms with intermediate-grade dysplasia now be categorized as low grade. Thus, "high-grade dysplasia" is to be reserved for only the uppermost end of the spectrum ("carcinoma in situ"-type lesions). (2) Current data indicate that PanIN of any grade at a margin of a resected pancreas with invasive carcinoma does not have prognostic implications; the clinical significance of dysplasia at a margin in a resected pancreas with IPMN lacking invasive carcinoma remains to be determined. (3) Intraductal lesions 0.5 to 1 cm can be either large PanINs or small IPMNs. The term "incipient IPMN" should be reserved for lesions in this size with intestinal or oncocytic papillae or GNAS mutations. (4) Measurement of the distance between an IPMN and invasive carcinoma and sampling of intervening tissue are recommended to assess concomitant versus associated status. Conceptually, concomitant invasive carcinoma (in contrast with the "associated" group) ought to be genetically distinct from an IPMN elsewhere in the gland. (5) "Intraductal spread of invasive carcinoma" (aka, "colonization") is recommended to describe lesions of invasive carcinoma invading back into and extending along the ductal system, which may morphologically mimic high-grade PanIN or even IPMN. (6) "Simple mucinous cyst" is recommended to describe cysts >1 cm having gastric-type flat mucinous lining at most minimal atypia without ovarian-type stroma to distinguish them from IPMN. (7) Human lesions resembling the acinar to ductal metaplasia and atypical flat lesions of genetically engineered mouse models exist and may reflect an alternate pathway of carcinogenesis; however, their biological significance requires further study. These revised recommendations are expected to improve our management and understanding of precursor lesions in the pancreas.