Endoscopic Ultrasonography–Guided Noninvasive Diagnosis of a Branch-Duct Intraductal Papillary Mucinous Neoplasm in a Heterotopic Pancreas

CASE REPORT

A 71-year-old woman with previous colorectal cancer was referred for a follow-up of a known pancreatic multifocal branch-duct intraductal papillary mucinous neoplasm (BD-IPMN). Computed tomography and magnetic resonance imaging performed in 2015 showed a 3-cm highly vascularized lesion suspicious for gastrointestinal stromal tumors uncertainly located between the antrum and duodenal bulb (Figure 1). A previous gastroscopy had shown a prepyloric semipedunculated submucosal lesion which was not reported in subsequent endoscopic ultrasound (EUS).

Figure 1.

Abdominal magnetic resonance imaging showing one of the pancreatic cysts and a round-shaped vascularized lesion uncertainly located between the antrum and duodenal bulb.

After screening for eventual IPMN evolution, an EUS showed a bulge in the postpyloric posterior wall of the duodenal bulb. This bulge corresponded to a 2.7-cm isoechoic lesion with a granular parenchymal pattern located in the third submucosal layer; an anechoic ductal structure of 2 mm was visible crossing the lesion toward a mucosal outlet; and a mucosal orifice was also endoscopically visible, with a transparent outflow (Figures 2 and 3). Furthermore, a 6-mm nonvascularized cyst was visible inside this lesion, with a small connection with the main ductal structure (Figure 2). Altogether, these findings were most suggestive of BD-IPMN inside a pancreatic rest (Figure 4).

Figure 2.

Endoscopic ultrasound showing a 2.7-cm isoechoic lesion with granular parenchymal pattern containing an anechoic ductal structure of 2 mm and a 6 mm cyst, with a small connection with the main ductal structure.

Figure 3.

Mucosal orifice endoscopically visible with a transparent outflow.

Figure 4.

Comprehensive synthesis of endoscopic ultrasound and endoscopic findings, showing the submucosal lesion suggestive for pancreatic rest, the ductal structure with its luminal opening (red arrows), and a small cyst with a visible connection (yellow arrow) to the duct.

Heterotopic pancreatic parenchyma is a nonmalignant abnormality whose prevalence has been reported ranging from 0.55% to 13.7% of autoptic series and 0.9% of surgical gastrectomies.¹ Differential diagnosis with potentially malignant mesenchymal tumors can be difficult, this often leading to invasive surgical management, but EUS characteristics and/or EUS-guided tissue acquisition can help.¹ IPMN development has been rarely reported as a possible complication of a heterotopic pancreas.^2,3 However, all reported cases were diagnosed after histological analysis of surgical specimens.^1,3,4 We here report the first case in which the diagnosis of a pancreatic rest with a small BD-IPMN could be presumed in vivo through EUS evaluation. Other differential diagnoses were possible, for instance, retention or inclusion cyst. However, these were less likely based on endoscopic appearance and the concomitant presence of a multifocal pancreatic IPMN, which is considered a field defect condition. In conclusion, the highly specific EUS findings within the patient's clinical history allowed us to perform a noninvasive diagnosis, avoiding both an unnecessary histological confirmation and a surgical overtreatment.

DISCLOSURES

Author contributions: All authors contributed equally to this manuscript. G. Vanella is the article guarantor.

Financial disclosure: None to report.

Informed consent was obtained for this case report.