Probe-based confocal laser endomicroscopy is an endoscopic technique that enables
Although endoscopic diagnosis of biliary disease is performed by endoscopic retrograde cholangiopancreatography (ERCP), endoscopic ultrasonography (EUS), intraductal ultrasonography, and cholangioscopy, the low sensitivity of transpapillary bile duct biopsy and bile juice cytology (BJC), and the high frequency of false-positive results from BJC are well-known clinical problems. Thus, additional endoscopic procedures are often required, and unnecessary surgery may sometimes be needed [
Probe-based confocal laser endomicroscopy (pCLE) has recently been anticipated as a new diagnostic tool. CLE is a breakthrough endoscopic technique that uses the fluorescent pigment, fluorescein, to observe cells
This study included seven patients who underwent pCLE of bile duct lesions with three types of probes: GastroFlexTM, a dedicated gastrointestinal probe; AlveoFlexTM (Mauna Kea Technologies), a dedicated lung probe; and CholangioFlexTM. Patients were enrolled from January 2015 to October 2018, and pCLE imaging findings and diagnostic ability were evaluated. These cases were part of a retrospective cohort study at a single center, Aichi Cancer Center Hospital in Nagoya, Japan, and was approved by the institutional review board of the hospital (approval number: 2020-1-083).
We present a case of distal bile duct cancer that was diagnosed by pCLE (case 5). A 79-year-old man visited our hospital for further examination of jaundice. Computed tomography showed distal bile duct stenosis with irregular thickening of the entire circumference of the wall and dilated peripheral bile duct. EUS showed hypoechoic wall thickness at the same site, and the border with pancreatic parenchyma was obscured. ERCP and magnetic resonance cholangiopancreatography showed irregular wall thickness of the entire circumference of the distal bile duct (
In this study, the pCLE system “Cellvizio” produced by Mauna Kea Technologies (Paris, France) and three types of probes with different specifications (GastroFlexTM/ CholangioFlexTM/ AlveoFlexTM; compatible operating channel: ≥2.8 mm/ ≥1 mm/ ≥1.9 mm; field of view: 240 μm/ 325 μm/ 600 μm; resolution: 1 μm/ 3.5 μm/ 3.5 μm; and confocal depth: 55–65 μm/ 40–70 μm/ 0–50 μm, respectively) were used; therefore, the characteristics of imaging findings obtained with each probe differed. CholangioFlexTM showed a collagen fiber network in the submucosa as a normal finding in the bile duct, and image quality was rough and often unclear. In addition, mucosal epithelium could not be confirmed in a routine manner. On the other hand, GastroFlexTM offered 3.5-times better image resolution than CholangioFlexTM; therefore, more detailed images could be visualized, as previously reported [
Here, we focused on epithelial findings that could be observed with GastroFlexTM, which enabled us to obtain detailed images. With the other two probes, epithelial findings were observed in only a single case (14.3%) each, whereas with GastroFlexTM, epithelial findings were observed in all cases due to the high image resolution. Since these results showed that using GastroFlexTM significantly (
We established new diagnostic criteria for epithelial findings from pCLE and evaluated its diagnostic ability. The following five findings were suggestive of malignancy: (1) CSD, where each cell is heterogeneous and differs in size; (2) CO, where epithelial cells that are normally present in monolayers appear to overlap instead; (3) IEC, where cell clumps are irregular owing to the ubiquity of the nucleus and weakening of cell adhesion molecules; (4) IS, where epithelial cell composition is irregular and complex; and (5) DE, where the nucleus and cytoplasm cannot be distinguished, as the entire cell appears dark (
As described above, pCLE using epithelial findings shows excellent diagnostic ability, and since epithelial findings themselves can also be easily compared with pathological findings, GastroFlexTM should be the first choice for pCLE of biliary diseases. However, pCLE does not provide findings about the cell nucleus, which is a very important factor in the diagnosis of malignancy; hence, we look forward to the development of fluorescent pigments that can enable the identification of nuclear findings.
In this study, three types of probes were used to diagnose biliary lesions. Since only a small number of studies have been reported, the most useful probe remains unclear, but GastroFlexTM impressively provided markedly clearer images than other probes. We consider the clarity of images from GastroFlexTM as essential to achieve high diagnostic ability. Diagnosis with pCLE based solely on epithelial findings using GastroFlexTM, without relying on the existing Miami classification of unclear submucosal findings, is expected to provide a useful new method for diagnosing biliary diseases. Accumulation of pCLE cases examined using GastroFlexTM is desirable, and diagnostic ability (including which of the epithelial findings are very important) must be verified in a larger number of cases.
Mizuno Nobumasa reports grants and personal fees from Novartis. The authors have no potential conflicts of interest.
None.
Conceptualization: Hiroki Koda, Kazuo Hara
Data curation: Takamichi Kuwahara
Validation: Okuno Nozomi, Mizuno Nobumasa, Shin Haba, Miyano Akira, Isomoto Hajime
Writing-original draft: HK
Writing-review&editing: KH
Imaging findings in bile duct cancer. (A) Computed tomography; (B) endoscopic retrograde cholangiopancreatography; (C) magnetic resonance cholangiopancreatography; (D) endoscopic ultrasonography. Various images show distal bile duct stenosis (yellow arrow) caused by irregular bilateral wall thickness.
Representative probe-based confocal laser endomicroscopy (pCLE) images of bile duct cancer. Malignant findings, based on the Miami classification, on pCLE with 3 types of probes produced by Mauna Kea Technologies (Paris, France) ((A-C) GastroFlexTM, (D, E) CholangioFlexTM, (F) AlveoFlexTM) are as follows. (A) Thick white bands; (B) dark clumps; (C) epithelial structure; (D) thick dark bands; (E) dark clumps; (F) dark clumps.
Normal and malignant findings in epithelial structures. (A) Normal bile duct: a sheet-like monolayer of uniform epithelial cells is arrayed on the right side, and a collagen fiber network in the submucosa is presented on the left side (the red dotted line represents the border). (B, C) Bile duct cancer: (1) Each cell is heterogeneous, and the cells differ in size: cell size difference, (2) Epithelial cells appear to overlap: cell overlap, (3) Irregularity of cell clumps: irregular edges of cell clumps, (4) Irregular and complex epithelial cell composition: irregular structure, (5) The nucleus and cytoplasm cannot be distinguished as the entire cell appears dark: dark epithelium.
Representative probe-based confocal laser endomicroscopy epithelial findings in 7 cases. (A) Cases 1 and 3: benign stricture due to surgery. Sheet-like monolayer of uniform epithelial cells. (B, D, E, F) Cases 2, 4, 5, and 6: bile duct cancer. Each cell is heterogeneous, and cells overlap and differ in size. (C) Case 3: normal bile duct. Sheet-like monolayer of uniform epithelial cells. (G) Case 7: IgG4-related sclerosing cholangitis. Cells are not sheet-like, but are relatively uniform in size, with no apparent overlap.
Patient Characteristics and Probe-Based Confocal Laser Endomicroscopy Findings
Age | Sex | Diagnosis | Lesion localization | GastroFlexTM |
CholangioFlexTM |
AlveoFlexTM |
Biopsy | Cytology | |
---|---|---|---|---|---|---|---|---|---|
DC/TWB/TDB/ES (CSD/CO/IEC/IS/DE) | DC/TWB/TDB/ES (CSD/CO/IEC/IS/DE) | DC/TWB/TDB/ES (CSD/CO/IEC/IS/DE) | |||||||
1 | 54 | F | Benign stricture due to surgery | Hilar bile duct | O/×/×/O (×/×/×/×/×) | O/×/×/× (not visualized) | O/×/×/× (not visualized) | No malignancy | No malignancy |
2 | 67 | F | BD cancer | Hilar bile duct | O/O/×/O (O/O/O/O/O) | ×/×/×/× (not visualized) | O/×/×/× (not visualized) | No malignancy | No malignancy |
3 | 70 | F | Normal bile duct (GB cancer) | Fundus of gallbladder | ×/×/×/O (×/×/×/×/×) | ×/×/×/× (not visualized) | ×/×/×/× (not visualized) | No malignancy | - |
4 | 80 | M | BD cancer | Hilar bile duct + Distal bile duct | O/×/×/O (O/O/O/O/O) | O/×/×/× (not visualized) | ×/×/×/× (not visualized) | Adenocarcinoma | Atypical cell |
5 | 79 | M | BD cancer | Distal bile duct | O/O/×/O (O/O/O/O/O) | O/×/O/× (not visualized) | O/×/×/× (not visualized) | Adenocarcinoma | Adenocarcinoma |
6 | 72 | M | BD cancer | Hilar bile duct + Distal bile duct | O/×/×/O (O/×/O/O/O) | ×/×/O/O (UD/UD/UD/UD/ UD) | O/×/×/× (not visualized) | Adenocarcinoma | Atypical cell |
7 | 72 | F | IgG4-SC | Hilar bile duct | O/×/×/O (×/×/×/×/×) | ×/×/×/× (not visualized) | O/×/×/O (×/×/×/×/×) | No malignancy | No malignancy |
Examination time (second), mean (SD) | 281.3 (±40.4) | 225.5 (±23.2) | 175.7 (±28.3) | ||||||
Sensitivity | N.S | 100% (4/4) | 75% (3/4) | 75% (3/4) | 75% (3/4) | 25% (1/4) | |||
Specificity | N.S | 0% (0/3) | 66.7% (2/3) | 33.3% (1/3) | 100% (3/3) | 100% (2/2) | |||
Accuracy | N.S | 57.1% (4/7) | 71.4% (5/7) | 57.1% (4/7) | 85.7% (6/7) | 50% (3/6) | |||
Sensitivity | N.S | 100% (4/4) | - | NaN | |||||
Specificity | N.S | 100% (3/3) | - | 0% (0/1) | |||||
Accuracy | N.S | 100% (7/7) | - | 100% (1/1) |
BD, bile duct; CO, cell overlap; CSD, cell size difference; DC, dark clumps; DE, dark epithelium; ES, epithelial structures; GB, gall bladder; IEC, irregular edges of cell clumps; IS, irregular structure; NaN, not a number; N.S, not significant; SD, standard deviation; TDB, thick dark bands; TWB, thick white bands; UD, undetermined.