Endoscopic Ultrasound Features Associated with Malignancy and Aggressiveness of Nonhypovascular Solid Pancreatic Lesions: Results from a Prospective Observational Study

Abstract

Background and Study Aims On contrast-enhanced imaging studies, nonhypovascular (i. e., isovascular and hypervascular) patterns can be observed in solid pancreatic lesions (SPLs) of different nature, prognosis, and management. We aimed to identify endoscopic ultrasound (EUS) features of nonhypovascular SPLs associated with malignancy/aggressiveness. The secondary aims were EUS tissue acquisition (EUS-TA) outcome and safety in this setting of patients.

Patients and Methods This prospective observational study included patients with nonhypovascular SPLs detected on cross-sectional imaging and referred for EUS-TA. Lesion features (size, site, margins, echotexture, vascular pattern, and upstream dilation of the main pancreatic duct) were recorded. Malignancy/aggressiveness was determined by evidence of carcinoma at biopsy/surgical pathology, signs of aggressiveness (perineural invasion, lymphovascular invasion, and/or microscopic tumor extension/infiltration or evidence of metastatic lymph nodes) in the surgical specimen, radiologic detection of lymph nodes or distant metastases, and/or tumor growth > 5 mm/6 months. Uni- and multivariate analyses were performed to assess the primary aim.

Results A total of 154 patients with 161 SPLs were enrolled. 40 (24.8 %) lesions were defined as malignant/aggressive. Irregular margins and size > 20 mm were independent factors associated with malignancy/aggressiveness (p < 0.001, OR = 5.2 and p = 0.003, OR = 2.1, respectively). However, size > 20 mm was not significant in the subgroup of other-than-neuroendocrine tumor (NET) lesions. The EUS-TA accuracy was 92 %, and the rate of adverse events was 4 %.

Conclusion Irregular margins on EUS are associated with malignancy/aggressiveness of nonhypovascular SPLs. Size > 20 mm should be considered a malignancy-related feature only in NET patients. EUS-TA is safe and highly accurate for differential diagnosis in this group of patients.

Zusammenfassung

Ziel In kontrastverstärkten Bildgebungsstudien werden in soliden Pankreasläsionen (SPLs) nicht hypovaskuläre (d. h. isovaskuläre und hypervaskuläre) Muster unterschiedlichsten Ursprungs, Prognose und Behandlung beobachtet. Unser Ziel war die Bestimmung der Merkmale des endoskopischen Ultraschalls (EUS) bei nicht hypovaskulären SPLs, die mit Malignität/Aggressivität assoziiert sind. Die sekundären Ziele waren das Outcome der EUS-Gewebeaufnahme (EUS-TA) und die Patientensicherheit.

Material und Methoden Diese prospektive Beobachtungsstudie umfasste Patienten mit nicht hypovaskulären SPLs, die in einem Schnittbildverfahren entdeckt wurden und zur EUS-TA einbestellt wurden. Läsionsmerkmale (Größe, Lage, Ränder, Echotextur, Gefäßmuster und stromaufwärts gerichtete Dilatation des Hauptpankreasgangs) wurden erfasst. Die Malignität/Aggressivität wurde durch Nachweis eines Karzinoms in der Biopsie/Pathologie, durch Zeichen von Aggressivität (perineurale Invasion, lymphovaskuläre Invasion und/oder mikroskopische Tumorausdehnung/-infiltration oder Nachweis metastasierter Lymphknoten) in der chirurgischen Probe, durch den radiologischer Nachweis von Lymphknoten oder entfernten Metastasen und/oder durch Tumorwachstum > 5 mm in 6 Monaten definiert. Zur Beurteilung des Primärziels wurden uni- und multivariate Analysen durchgeführt.

Ergebnisse Insgesamt wurden 154 Patienten mit 161 SPLs aufgenommen. 40 (24,8 %) Läsionen wurden als maligne/aggressiv definiert. Unabhängige, mit Malignität/Aggressivität assoziierte Faktoren waren unregelmäßige Ränder (p < 0,001; OR = 5,2) und eine Größe > 20 mm (p = 0,003; OR = 2,1). Allerdings war der Faktor Größe > 20 mm in der Untergruppe der nicht neuroendokrinen Tumor (NET) -Läsionen nicht signifikant. Die Genauigkeit der EUS-TA betrug 92 % und die Rate der unerwünschten Ereignisse 4 %.

Schlussfolgerung Unregelmäßige Ränder in EUS sind mit Malignität/Aggressivität von nicht hypovaskulären SPLs assoziiert. Eine Größe > 20 mm sollte nur bei NET-Patienten als Marker für Malignität angesehen werden. Die EUS-TA ist sicher und von hoher Genauigkeit für die Differenzialdiagnose in dieser Patientengruppe.

Key words

pancreas - neuroendocrine tumor - pancreatic cancer

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