Narrowband imaging colonoscopy with a transparent hood for diagnosis of a squamous cell carcinoma in situ in the anal canal

Accuracy of narrow-band imaging in predicting the histology of anal intraepithelial lesions

BACKGROUND AND AIM

Anal intraepithelial neoplasia (AIN) is the precursor of anal squamous carcinoma, frequently underappreciated by most gastroenterologists. Purpose of the study is to assess the diagnostic accuracy of narrow-band imaging (NBI) in predicting the histology of anal lesions, considering a new NBI classification.

METHODS

This is a retrospective analysis of consecutive patients with suspected anal squamous intraepithelial lesions (SILs) and superficially invasive squamous cell carcinoma (SISCCA) who underwent anorectal-sigmoidoscopy. Three expert endoscopists reviewed all the images collected during colonoscopies in white light and NBI in order to generate a practical classification of three main different NBI patterns.

RESULTS

After the modified Delphi process, the final NBI classification, mainly based on intrapapillary capillary loops (IPCL) changes included three different NBI pattern. NBI pattern I: elongation of IPCL toward epithelial surface; NBI pattern 2: thickened and tortuous IPCL; NBI pattern 3: mosaic-like disposition of IPCL. We found that NBI pattern positively correlated to the histologic type of the lesions and tumor grade (Spearman's rho = 0.9671, P = 0.0000). Among 58 anal lesions included, 41/41 (100%) LSILs have been classified as NBI pattern I, 10/11 (90.91%) HSILs as NBI pattern II, 1/11 HSIL as NBI pattern I, 4/4 SISCCA as NBI pattern III and 2/2 invasive cancer as NBI pattern III. Diagnostic accuracy of NBI pattern II or III in predicting histology differentiating HSIL or SISCCA/IC versus LSIL showed a sensitivity of 100%, (95% CI: 92.3-100%) and a specificity of 94.1% (95% CI: 83.8-98.3%).

CONCLUSION

The accuracy of this new NBI score system in predicting the histology of anal lesions showed encouraging data in term of sensitivity and specificity in differentiating HSIL or SISCCA/IC versus LSIL, but the clinical usefulness and application of these findings should be evaluated in a prospective larger study.

Anal Intraepithelial Neoplasia: Precursor of Anal Squamous Cell Carcinoma

Anal squamous cell carcinoma (SCC) is rare, but it has been commonly detected as an invasive cancer. The standard treatment for anal SCC was surgical resection. However, recent medical advances have enabled the standard treatment to be chemoradiotherapy. Anal intraepithelial neoplasia (AIN) is a premalignant lesion of SCC. The screening test for AIN and human papilloma virus vaccine are important for the following high-risk patients: patients positive for human immunodeficiency virus and men who have sexual intercourse with men. Although cytology can be easily applied for a screening test, the false-negative rate for AIN is high. Instead, high-resolution anoscopy (HRA) has been gaining attention as a promising screening method for high-risk patients. Investigations comparing characteristic findings of HRA with the histology of AIN have demonstrated that HRA is a highly specific test for AIN.

Magnifying or image-enhanced endoscopies are also routinely used for colonoscopy, as they allow detailed observations at higher magnifications than those of HRA. Hence, these endoscopic modalities can be applied for assessing AIN. Ablation therapies or topical medications are available as the local treatment for AIN. Although endoscopic submucosal dissection is considered to be feasible to remove AIN, it has a technical difficulty to approach endoscopically invisible areas. Hence, this technique may be useful to resect AIN localized in the endoscopically visible areas, when the localization is confirmed via targeted biopsy.

A novel Lugol's iodine staining technique to visualize the upper margin of the surgical anal canal intraoperatively for Hirschsprung disease: a case series

Background

In cases of Hirschsprung disease, complete and reproducible resection of the aganglionic bowel is ideal to achieve good postoperative bowel function. Reliable identification of the upper margin of the surgical anal canal, which is the squamous-columnar junction, is necessary during transanal pull-through. Here, we describe a novel staining technique using Lugol’s iodine stain to visualize the upper margin of the surgical anal canal.

Methods

Lugol’s iodine staining was performed in five patients with Hirschsprung disease treated using a single-stage laparoscopic transanal pull-through modified Swenson procedure. In two of these patients, endocytoscopic observation with ultra-high magnification was performed using methylene blue and crystal violet to mark the border of the squamous epithelium at 1 week before surgery. The alignment between the incisional line, which was revealed using Lugol’s iodine staining and endocytoscopic marking, was evaluated. Complications, including postoperative bowel dysfunction, were evaluated.

Results

In all cases, Lugol’s iodine staining produced a well-demarcated line. The endocytoscopic marking of the upper margin of the surgical anal canal was aligned with the line revealed by Lugol’s iodine staining. There were no complications associated with the transanal pull-through procedure, including postoperative bowel dysfunction.

Conclusions

Lugol’s iodine staining could be a safe and practical method to visualize the upper margin of the surgical anal canal intraoperatively. This finding may be useful for surgeons to make a consistent removal of the aganglionic bowel during surgery for Hirschsprung disease.

The prospect of endoscopic submucosal dissection for early anal canal squamous cell carcinoma

Squamous cell carcinoma (SCC) of the anal canal is seldom diagnosed at an early stage. Chemoradiation therapy is a standard in Europe and the United States, though in squamous cell carcinoma there is no evidence-based therapy. In Japan, endoscopic submucosal dissection (ESD) is the standard minimally invasive treatment for early stage cancer of the digestive tract, including the colorectum. Therefore, if the lesion is diagnosed at an early stage, ESD may be selected for anal canal lesions. We experienced two cases of early stage anal canal cancer in which the diagnosis and the extent of the lesions were confirmed using magnifying endoscopy with narrow-band imaging (NBI), as well as performing ESD. Pathological examination showed the resected specimen to be SCC in situ; the horizontal and vertical margins were free of tumor; and in one case there was no lymphovascular invasion. In the other case it showed the tumor was contained within the epithelium; horizontal and vertical margins were free of tumor; The follow-up period is not long enough to assert that ESD for anal canal squamous cell carcinoma may be an option of minimally invasive therapy. However, if there is a possibility of lymphatic invasion as in one of our cases, we need to give serious consideration to ESD for these lesions, and careful follow-up is necessary even if the lesion is in situ.

Detection of anal dysplasia is enhanced by narrow band imaging and acetic acid

AIM

Anal intraepithelial neoplasia precedes the development of anal squamous cell carcinoma. Detection of the lesion is essential to management. This paper describes a prospective study to detect and ablate anal squamous intraepithelial lesions (SILs) using white light narrow band imaging (NBI) and NBI with acetic acid (NBIA).

METHOD

Sixty patients with abnormal anal cytology and risk factors for anal dysplasia underwent examination of the anoderm with a high definition gastroscope and NBIA. Targeted biopsies were taken and the lesions were ablated and characterized histopathologically. Visualization of the anal transitional zone was facilitated by retroflexion and examination through a disposable anoscope.

RESULTS

Targeted biopsies were taken from lesions in 58 patients. No lesion was seen in two patients. Histopathology showed SIL in 48 (80.0%) of 60 biopsies. One biopsy showed lymphoid aggregates. Biopsies in nine (15%) of the 60 patients showed normal mucosa. Lesions were seen in white light in 27 (45%) of the 60 cases, NBI in 39 (65%) and NBIA in 57 (95%). There was no major morbidity. Sensitivity analysis showed that all methods were significantly different from each other.

CONCLUSION

Anal SIL in the anal transitional zone and anal canal can be identified by NBIA. Patient selection influences findings. Limitations include small sample size and non-randomization.

Endoscopic submucosal dissection of a squamous cell carcinoma in situ in the anal canal diagnosed by magnifying endoscopy with narrow-band imaging

A 60-year-old female underwent screening colonoscopy. Narrow-band imaging (NBI) without magnification showed a 20-mm, well-demarcated brownish area located close to the dentate line of the anal canal. Conventional white-light imaging revealed an ill-defined, flat lesion with scattered reddish spots at the same site. Magnifying endoscopy with NBI (M-NBI) revealed abnormal microvessels with dilatation, tortuosity, caliber change and various shapes that were similar to the intrapapillary capillary loop patterns seen in esophageal squamous cell carcinoma in situ. Endoscopic submucosal dissection (ESD) was performed, and on histological examination, the resected specimen showed squamous cell carcinoma (SCC) in situ and clear surgical margins. Thus, NBI is an efficient method for detecting superficial SCC in the anal canal and M-NBI may be useful for determining the extent of the lesion. During screening colonoscopy, the anal region should be carefully observed using NBI, as early detection offers a greater opportunity for ESD which is a less invasive procedure.

Beneficial use of magnifying endoscopy with narrow-band imaging for diagnosing a patient with squamous cell carcinoma of the anal canal

The patient was a 74-year-old woman. She visited a dermatology clinic with a complaint of discomfort in the anal region. Erosion was observed in the anal region, and biopsies were performed. She was diagnosed with Bowen's disease and was referred to the dermatology department of our hospital for treatment. At our department, an endoscopic examination was performed for assessing the extent of Bowen's disease in the rectum. A retroflexed view of the anal canal revealed a slightly raised lesion with a faded color and an irregular surface. Narrow-band imaging (NBI) revealed a whitish lesion with a relatively clear margin and brown dots on the inside. Magnifying endoscopy with NBI revealed abnormal microvessels with dilatation, tortuosity, caliber change and various shapes, which were quite similar to the intrapapillary capillary loop patterns of superficial esophageal cancer. A complete transanal resection of the anal mucosa was performed thereafter. The patient was diagnosed with a well-differentiated squamous cell carcinoma on the basis of a pathological examination. An early diagnosis is critical for successful treatment of anal canal cancer. In this regard, magnifying endoscopy with NBI may be useful for determining the presence and extent of anal canal cancer.