Clin Endosc.  2024 May;57(3):393-401. 10.5946/ce.2023.068.

The role of needle-based confocal laser endomicroscopy in the diagnosis of pancreatic neuroendocrine tumors

• Yamada M
• Hara K
• Mizuno N
• Haba S
• Kuwahara T
• Okuno N
• Kuraishi Y
• Yanaidani T
• Ishikawa S
• Yasuda T
• Fukui T

• KMID: 2555901
• DOI: http://doi.org/10.5946/ce.2023.068

Abstract

Background/Aims
Endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) is a highly accurate method for diagnosing pancreatic neuroendocrine tumors (PNETs); however, some PNETs are difficult to diagnose. Recently, the efficacy of needle-based confocal laser endomicroscopy (nCLE) in diagnosing solid pancreatic masses has been reported. However, the efficacy of nCLE in the diagnosis of PNETs remains unknown and only a small number of cases have been reported. Hence, this study aimed to evaluate the efficacy of nCLE in the diagnosis of PNETs.
Methods
This single-center retrospective study evaluated 30 consecutive patients with suspected PNETs on contrast-enhanced computed tomography, who consented to nCLE combined with EUS-FNA and were diagnosed using EUS-FNA or surgical resection. The diagnostic criteria for PNETs using nCLE were based on the nesting and trabecular and glandular arrangement of tumor cell clusters surrounded by capillary vessels and fibrosis, as reported in previous studies.
Results
The diagnosis using nCLE was classified into three categories: misdiagnosis in three cases (10%), non-diagnostic in six cases (20%), and diagnostic in 21 cases (70%). nCLE was able to diagnose PNET in one of the two cases with inconclusive EUS-FNA.
Conclusions
Although further development of the resolution and optimization of the diagnostic criteria are required, nCLE may constitute a useful diagnostic option in cases of inconclusive EUS-FNA for PNETs.

Keyword

Confocal endomicroscopy; Endoscopic ultrasound; Fine-needle aspiration; Fine-needle biopsy; Pancreatic neuroendocrine tumor

Figure

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  Fig. 1. Typical needle-based confocal laser endomicroscopy images of pancreatic neuroendocrine tumors (PNETs). (A) Typical findings of PNETs. (B) Nesting, trabecular, and glandular arrangements of tumor cell clusters. (C) Surrounding capillary vessels and fibrosis. (D) These findings are consistent with the histological structure (hematoxylin and eosin staining, ×400).

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  Fig. 2. A case of inconclusive endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA). (A, B) The lesion is detected in the pancreatic body using enhanced computed tomography and EUS. (C) The needle-based confocal laser endomicroscopy image shows typical findings of pancreatic neuroendocrine tumor (PNET). (D) EUS-FNA shows no tumor cells in the cell block (×100). (E) Histopathological view of the surgical specimen (hematoxylin and eosin staining, ×20). (F) The pathological diagnosis is PNET, G1. F-1: hematoxylin and eosin staining, ×100; F-2: synaptophysin is positive, ×100; F-3: chromogranin A is positive, ×100; F-4; Ki-index is <1%, ×100.

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  Fig. 3. Needle-based confocal laser endomicroscopy images of misdiagnosed and non-diagnostic cases. (A) Superficial vascular network. (B) Small cells with vascular bundles. (C) Small dark cells that are isolated. (D) Fine white fibrous bands.

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  Fig. 4. Examples of misdiagnosed and non-diagnostic cases (Case 1 from Table 3). (A, B) Lesions are detected in the pancreatic tail using contrast-enhanced computed tomography and endoscopic ultrasound. (C) The needle-based confocal laser endomicroscopy image shows only fine white fibrous bands. (D) Histopathological examination of the surgical specimen shows rich stromal fibrosis in the tumor (hematoxylin and eosin staining, ×20).

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