From the Guidelines
An irregular squamocolumnar junction refers to an uneven border between the squamous and columnar epithelium at the gastro-oesophageal junction, which can be a normal variant but may also be associated with reflux disease or potentially precancerous changes. The squamocolumnar junction is the area where the squamous epithelium of the oesophagus meets the columnar epithelium of the stomach. An irregular squamocolumnar junction, also known as an irregular Z-line, appears with tongues of columnar epithelium shorter than 1 cm and with no confluent columnar-lined segment 1. Some key points to consider about an irregular squamocolumnar junction include:
- It can be found with higher frequency in patients with reflux disease 1
- About 40% of cases of irregular Z-line may harbour intestinal metaplasia on biopsy samples, although the significance of this endoscopic finding is still unclear 1
- The presence of pure fundic/oxyntic mucosa is a very rare finding in Barrett’s oesophagus, and this pathological finding would suggest sampling of the GOJ 1
- Biopsies are generally not recommended if there is an irregular Z-line, but according to the degree of suspicion, biopsies may be performed to aid the diagnosis 1
- If the biopsy specimens are taken within an irregular Z-line, with no clear endoscopic evidence of Barrett’s, they should be labelled as GOJ and not oesophageal biopsy samples 1. In clinical practice, an irregular squamocolumnar junction should be distinguished from Barrett’s oesophagus, and a minimum length of 1 cm (M of Prague criteria) should be used for an endoscopic diagnosis of Barrett’s oesophagus 1.
From the Research
Definition of Squamocolumnar Junction
- The squamocolumnar junction (SCJ) is the area where the squamous epithelium meets the columnar epithelium in the cervix 2.
- It is the susceptible zone for precancer/cancer and is an important area to examine during cervical cancer screening 3.
Visibility of Squamocolumnar Junction
- The visibility of the SCJ declines substantially with age, with the majority of people screened having at most partially visible SCJ by the late 40s 3.
- The visibility of the SCJ is also affected by the type of examination, with live colposcopic exams resulting in significantly higher SCJ visibility compared to review of static images 3.
- The adequacy of visual inspection with acetic acid (VIA) declines with age, but the majority of women, even in older age groups, have adequate examinations 4.
Irregular Squamocolumnar Junction
- An irregular Z-line is characterized by a squamocolumnar junction that extends proximally above the gastroesophageal junction by <1 cm, whereas Barrett's esophagus is defined as a columnar-lined esophagus that extends proximally by ≥1 cm with the presence of specialized intestinal metaplasia on biopsy sampling 5.
- A computer-generated algorithm can be used to standardize the characterization of the SCJ, with a wavelet energy coefficient optimal threshold to classify an SCJ as irregular determined to be 1.53 × 10^7 with an accuracy of 78% 5.
- The definition of an irregular SCJ is not standardized, and there is variability in the clinical and histologic definitions of the cervical transformation zone and SCJ 2.
Implications of Irregular Squamocolumnar Junction
- An irregular SCJ can lead to increased difficulty in diagnosis and management of cervical precancers 3.
- Cervical cancer screening programs reliant on visual assessment might consider lowering the upper age limit for screening if there are not adequately trained personnel and equipment to evaluate and manage participants with inadequately visible SCJ 3.
- The use of endocervicoscopy and targeted biopsy can be a reliable method to detect the transformation zone in patients with type 3 transformation zone and unsatisfactory colposcopy, but presents a relatively low specificity/negative predictive value to predict high-grade cervical intraepithelial neoplasia 6.