Aims

Widespread use of immune checkpoint inhibitors (ICIs) for treatment of advanced malignancies led to an increase in number of immune-related adverse events such as ICI gastrointestinal (GI) injury (ICIGI). The resulting immune dysregulation of the GI mucosa is believed to predispose patients to viral infections. We characterised the histopathological features of ICIGI and the frequency of viral infections such as cytomegalovirus (CMV), adenovirus, and Epstein-Barr virus (EBV).

Methods

Single-centre retrospective study (2011-2020).

Results

81 GI biopsies from 31 patients with ICIGI (65% male (20/31), 35% female (11/31)) with advanced malignancies were reviewed. Most patients received ipilimumab and nivolumab (14/31, 45%), followed by pembrolizumab (9/31, 29%), ipilimumab (4/31, 13%), nivolumab (2/31, 6%) and combination of all three medications (2/31, 6%). Average regimen prior to incidence of diarrhea was three cycles. Evidence of colitis or erythema by endoscopy was present in 77% of cases, while 23% showed normal endoscopy. Histologically, the predominant ICIGI findings were active inflammation (84%), including cryptitis (77%), crypt abscesses (65%), lymphocytic colitis-like (LCL) pattern (61%), increase in epithelial apoptosis (74%) and/or surface injury (81%). Only one case showed diffuse CMV positivity (3%) with characteristic CMV viral cytopathic effects present on H&E stain and four cases were positive for rare EBV (13%). Adenovirus infection was not identified.

Conclusion

While our cohort is small, ICIGI generally demonstrates active inflammation including cryptitis and crypt abscesses in the colon, LCL pattern, and an increase in epithelial apoptosis. Upfront immunohistochemistry for viral infection without high-degree of clinical and histologic suspicion is not recommended.

BACKGROUND: In inflammatory bowel disease (IBD), many scenarios call for fecal diversion, leaving behind defunctionalized bowel. The theoretical risk of colorectal cancer (CRC) in this segment is frequently cited as a reason for resection. To date, no studies have characterized the incidence of neoplasia in the diverted colorectal segments of IBD patients. METHODS: A retrospective cohort analysis was conducted for IBD patients identified through a tertiary care center pathology database. Patients that had undergone colorectal diversion and were diverted for ≥ 1 year were included. Incidence of diverted dysplasia/CRC was calculated for Crohns disease (CD) and ulcerative colitis (UC) with respect to diverted patient-years (dpy) and patient-years of disease (pyd). RESULTS: In total, 154 patients comprising 754 dpy and 1984 pyd were analyzed. Only 2 cases of diverted colorectal dysplasia (CD 1, UC 1) and 1 case of diverted CRC (UC) were observed. In the UC cohort (n = 75), the rate of diversion-associated CRC was 4.5 cases/1000 dpy (95% CI 0.11-25/1000) or 1.5 cases/1000 pyd (95% CI 0.04-8.2/1000). In the CD cohort (n = 79), no patients developed CRC, although a dysplasia rate of 1.9 cases/1000 dpy (95% CI 0.05-11/1000) or 0.77 cases/1000 pyd (95% CI 0.02-4.3/1000) was observed. All patients developing neoplasia had disease duration > 10 years and microscopic inflammation. CONCLUSIONS: Diverted dysplasia occurred infrequently with rates overlapping those reported in registries for IBD-based rectal cancers. Neoplasia was undetected in patients with < 10 pyd, regardless of diversion duration, suggesting low yield for endoscopic surveillance before this time.