# A Case of Late Radiation-Induced Enteritis with Enterolith Caused Enterocutaneous Fistula

## TL;DR

A patient developed late radiation-induced enteritis and an enterocutaneous fistula due to an enterolith, requiring multiple surgeries and leading to short bowel syndrome.

## Contribution

This case highlights the rare but severe complication of enterolith formation due to late radiation-induced enteritis.

## Key findings

- Late radiation-induced enteritis can lead to enterolith formation and subsequent enterocutaneous fistula.
- Massive intestinal resection was required, resulting in short bowel syndrome with no recurrence of complications after three years.

## Abstract

Radiotherapy for pelvic malignancies contributes to improved patient survival. However, early and late radiation-induced complications are increasing and cause significant impairment of quality of life. We reported a case of late radiation-induced enteritis associated with an enterocutaneous fistula suggestive of enterolith, which required 2 times of surgical treatments.

A 70-year-old female in a postoperative state of bladder cancer was treated with neoadjuvant chemotherapy followed by surgery. Total radiotherapy at 61.2 Gy was performed 1 month after surgery. The patient had intestinal obstruction 6 months after completing irradiation. As the intestinal obstruction was refractory to conservative treatment, she underwent surgical treatment. Because of the difficulty of adhesiolysis, bypass surgery between the jejunum at 150 cm from the Treitz ligament and the ascending colon was performed. The postoperative course was good. However, an enterocutaneous fistula, likely associated with an enterolith, occurred 45 months after surgery. The development of enterolith was considered to be due to intestinal stenosis associated with late-induced radiation injury. Because the conservative treatment did not improve, she had to undergo surgical treatment. The surgical findings showed that most of the small intestine was adhered and immobilized. An enterocutaneous fistula was formed through the abscess with an enterolith. A massive intestinal resection was performed, resulting in a short bowel syndrome. Macroscopically, edematous changes in the submucosal layer of the wall and thickening of the ileum were observed. Histopathological examination revealed fibrosis and vascular obstruction in the mesentery. Atrophy and reduced crypts of the villi, as well as eosinophil infiltration, were observed, indicating the occurrence of late radiation injury. Therefore, we diagnosed that enterolith due to radiation-induced late enteritis caused intestinal obstruction and enterocutaneous fistula. Three years after intestinal resection, there was no recurrence of bowel obstruction and no evidence of severe malnutritional status.

Radiotherapy improves the survival of cancer patients. Nevertheless, irreversible and progressive late radiation-induced enteritis needs to be considered. Intensive follow-up is required to avoid severe complications or provide early treatment.