Multi-detector computed tomography imaging of inflammatory colonic strictures in recurrent acute pancreatitis: a case description and literature analysis

Introduction

Acute pancreatitis (AP) is a common digestive system disease that results in a regional or systemic inflammatory response (1). About 20–25% of patients with AP will experience more than two attacks of AP, which is known as recurrent acute pancreatitis (RAP) (2). RAP is defined as more than two attacks of AP without any evidence of underlying chronic pancreatitis (3). The associated inflammatory insult in RAP can spread to near neighboring structures and/or organs, causing extensive and severe damage to multiple organs and structures, potentially endangering life (4).

The inflammatory exudation of AP spreads to nearby organs through the retroperitoneal space, including the peripancreatic soft tissue, colon, and mesocolon (5,6). The colon is one of the most common sites of involvement in AP (7). In RAP, the colon is prone to inflammatory stenosis and fistula formation due to multiple inflammatory exudation involvement. In this article, we describe a case of RAP resulting in inflammatory colonic strictures, analyze a series of imaging characteristics on multi-detector computed tomography (MDCT), and conduct a literature review.

Case presentation

All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patient for publication of this article and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

An 82-year-old male patient was admitted to Women and Children’s Hospital of Chongqing Medical University, following three episodes of AP between July and November 2022. The patient had habits of drinking alcohol and smoking. His past history included hemorrhagic fever and chronic obstructive pulmonary disease; his family history was unremarkable. The patient attended Emergency Department on July 6, 2022 due to severe upper abdominal pain, bloating, nausea, and vomiting for one day. Blood tests showed an increased level of serum amylase and lipase indicating AP. The patient was then referred to the Gastroenterology Department for inpatient treatment.

On the second day (July 7, 2022) and 10th day (July 15, 2022) after admission, the patient underwent both an abdominal MDCT plain scan and enhanced computed tomography examination. The first abdominal MDCT images showed peripancreatic exudation with a heterogeneous non-liquid density (Figure 1A, as indicated by arrows), spreading to the sulcus adjacent to the descending colon (Figure 1B, as indicated by arrows). Based on the imaging findings, the patient was diagnosed with the peripancreatic necrosis type of AP. The second abdominal MDCT images showed partial absorption of peripancreatic exudation (Figure 2A, as indicated by arrows) and complete absorption of exudation around the descending colon compared to the first abdominal MDCT images (Figure 2B). In addition, swelling and thickening of the local intestinal wall in the lower segment of the descending colon (Figure 2B, as indicated by the long arrow), increased density of the adjacent colon mesentery, and an increased number of small blood vessels in the colon mesentery (Figure 2B, as indicated by short arrows) were observed on the second abdominal MDCT images. After 15 days of symptomatic treatment, the AP symptoms improved, and the patient recovered and was discharged from the hospital.

Figure 1 First abdominal enhanced MDCT images of an 82-year-old male patient suffering from a first acute pancreatitis attack. The abdominal MDCT images showed peripancreatic exudation with a heterogeneous non-liquid density (A; as indicated by arrows), spreading to the sulcus adjacent to the descending colon (B; as indicated by arrows). MDCT, multi-detector computed tomography.

Figure 2 Second abdominal enhanced MDCT images of an 82-year-old male patient suffering from a second acute pancreatitis attack. The second abdominal MDCT images showed partial absorption of peripancreatic exudation (A; as indicated by arrows) and complete absorption of exudation around the descending colon compared to the first abdominal MDCT images. In addition, swelling and thickening of the local intestinal wall in the lower segment of the descending colon (B; as indicated by the long arrow), increased density of the adjacent colon mesentery, and an increased number of small blood vessels in the colon mesentery (B; as indicated by short arrows) were observed on the second abdominal MDCT images. MDCT, multi-detector computed tomography.

Two months after being discharged following the first episode of AP, the patient experienced two more episodes of AP in September and November 2022, respectively. After 9 days of conservative and symptomatic treatment for the second episode of AP in September 2022, the AP symptoms improved, and the patient recovered and was discharged. During the hospitalization for the third episode of AP in November 2022, the first plain abdominal MDCT images showed exudation around the pancreas (Figure 3A, as indicated by arrows), and local intestinal wall edema and thickening, and intestinal lumen stenosis in the distal descending colon (Figure 3B, as indicated by the arrow). No dilation of the proximal intestinal lumen was observed on the abdominal MDCT images.

Figure 3 Plain abdominal MDCT images of an 82-year-old male patient suffering from a third acute pancreatitis attack. The plain abdominal MDCT images showed exudation around the pancreas (A; as indicated by arrows), local intestinal wall edema and thickening, and intestinal lumen stenosis in the distal descending colon (B; as indicated by the arrow). MDCT, multi-detector computed tomography.

After fasting, inhibition of enzyme activity, anti-infection, promotion of intestinal motility, maintenance of water and electrolyte balance, nutritional support, and symptomatic treatment, the AP symptoms were relieved. However, the patient’s hemoglobin level gradually decreased during hospitalization, and multiple fecal occult blood tests showed positive results. On the 13th day of hospitalization, the patient experienced a sudden worsening of abdominal pain, and ceased defecating and venting from the anus.

The patient underwent a second abdominal MDCT plain scan and enhanced computed tomography examination. The second abdominal MDCT images showed a reduction in peripancreatic exudation compared to the first plain scan abdominal MDCT images (Figure 4A, as indicated by arrows). However, local intestinal wall edema and thickening, and intestinal lumen stenosis in the distal descending colon (Figure 4B, as indicated by the long arrow), along with the intestinal dilation and fluid accumulation of the proximal colon and small intestine (Figure 4B, short arrows) were observed on the second abdominal MDCT images, indicating the occurrence of a low-level and incomplete intestinal obstruction. After multidisciplinary consultation and communication with the patient’s family, it was decided that a surgical resection of the narrow segment of the colon would be performed after the patient’s AP condition improved.

Figure 4 Second abdominal enhanced MDCT images of an 82-year-old male patient suffering from a third acute pancreatitis attack. The second abdominal MDCT images showed a reduction in peripancreatic exudation compared to the first plain abdominal MDCT images (A; as indicated by arrows). However, local intestinal wall edema and thickening, and intestinal lumen stenosis in the distal descending colon (B; as indicated by the long arrow), along with intestinal dilation and fluid accumulation of the proximal colon and small intestine were observed on the second abdominal MDCT images (B; as indicated by short arrows). MDCT, multi-detector computed tomography.

After 17 days of treatment for the third episode of AP, the patient’s condition improved. The patient was referred to the Department of Gastrointestinal Surgery for the surgical removal of a narrow segment of the colon. An X-ray colonoscopy was performed before surgery, showing a narrowing of the intestinal lumen at the junction of the descending and sigmoid colon (Figure 5, as indicated by the arrow). The patient was scheduled to undergo surgical resection of the narrow segment of the intestinal tract and single-lumen colostomy by laparoscopy. During the operation, a narrow segment of the intestinal tract (about 5 cm in length) was observed at the junction of the descending and sigmoid colon. The diameter of the proximal intestinal tract dilation was about 5 cm. At a distance of approximately 5.0 cm from the lower edge of the narrow intestinal segment, the sigmoid colon was severed and fixed beneath the left iliac spine. At a distance of 10 cm from the upper edge of the narrow segment of the intestinal tract, the descending colon was severed and a single lumen colonic fistula was created by pulling out the abdominal wall through a left upper rectus abdominis incision. The removed tissue specimen was then sent to the Pathology Department for histopathological examination.

Figure 5 An X-ray colonoscopy of an 82-year-old male patient with acute pancreatitis. The X-ray colonoscopy showed a narrowing of the intestinal lumen at the junction of the descending and sigmoid colon (as indicated by the arrow).

A slice of hematoxylin and eosin staining showed fibroblast proliferation and scattered chronic inflammatory cell infiltration (Figure 6A), and immunohistochemical staining showed the positive expression of smooth muscles actin and Desmin (Figure 6B). Based on the histopathological findings, the diagnosis of chronic suppurative inflammation of the colon with smooth muscle hyperplasia was confirmed. After 3 months, the patient underwent an additional surgery at the descending colostomy site.

Figure 6 Light microscopy findings and immunohistochemical staining of a narrow segment of the intestinal tract. A slice of hematoxylin and eosin staining showed fibroblast proliferation and scattered chronic inflammatory cell infiltration (A). Immunohistochemical staining showed the positive expression of smooth muscles actin and Desmin (B). Based on the histopathological findings, the diagnosis of chronic suppurative inflammation of the colon with smooth muscle hyperplasia was confirmed.

Discussion

Most patients who have had an attack of AP are at risk of recurrence if the offending cause/agent is not removed/eliminated. Of the common causes of AP, gallstones and alcohol are most likely to cause RAP (8). The patient in our case reported that he had a habit of drinking alcohol, which might have been the main cause of his RAP. AP has attracted clinical attention due to the uncertainty about its natural course in terms of recurrence and long-term outcome (9). In this case report, we described a course of RAP and its changes as captured by a series of MDCT imaging features taken during the course of disease recurrence, providing valuable insights into the clinical diagnosis and treatment of RAP and colonic complications.

Based on the location of necrosis, acute necrotizing pancreatitis can be divided into three types: pancreatic parenchymal necrosis, peripancreatic necrosis, and mixed necrosis (10). Peripancreatic necrosis is a subtype of acute necrotizing pancreatitis, which may be caused by leakage of pancreatic enzymes leading to necrosis of peripancreatic fat or/and tissue (11). In this case, peripancreatic exudation at the body and tail of the pancreas revealed heterogeneous non-liquid density on MDCT, and the patient was diagnosed with the peripancreatic necrosis type of AP.

Mohamed et al. (12) reported that the transverse colon and splenic flexure are most frequently involved in severe AP, with the transverse colon prone to fistula formation, and the splenic flexure prone to stenosis. To our knowledge, the stenosis at the junction between the descending and sigmoid colon caused by RAP had not been reported. In this case, the peripancreatic exudation located in the body and tail of the pancreas was prone to spreading to the left paracolic sulcus through anatomical gaps, thereby involving the descending colon (13). The anatomical location of the junction between the descending colon and the sigmoid colon is relatively low. The exudation that accumulates at the site in RAP repeatedly involves this segment of the intestinal tract, leading to swelling and thickening of the intestinal wall, and even stenosis of the intestinal lumen or the formation of fistulas.

Pancreatic or/and peripancreatic necrosis may be the result of local vascular spasm and increased intravascular coagulability in severe AP (14). This vascular complication can also occur in adjacent organs if the inflammatory insult is sufficiently strong. Two mechanisms have been proposed for colon stenosis in AP (15): direct diffusion of pancreatic enzymes leading to enzymatic digestion of the intestine; and blood vessel obstruction or spasm in the mesenterium caused by severe inflammation leading to intestinal ischemia or stenosis. In this case of RAP, a higher density of the mesentery adjacent to the narrow segment of the intestine, and an increased number of small blood vessels in the mesentery were observed on MDCT. These MDCT signs indicated that the blood vessels supplying the narrow segment of the intestinal tract were repeatedly involved in inflammatory exudation, and also confirmed the credibility of the mechanism theory about AP induced intestinal stenosis mentioned above. In addition, Smit et al. reported that severe AP may be accompanied by intra-abdominal hypertension (IAH) and abdominal compartment syndrome (16). After an increase in idiopathic AP, intestinal mucosal perfusion and mesenteric artery blood flow are significantly reduced, indicating that IAH may be one of the mechanisms of early intestinal injury in severe AP (17). Further research needs to be conducted to confirm this hypothesis.

Colonic strictures tend to be late manifestations and largely present as bowel obstruction in AP. Mohamed et al. (12) reported that colonic strictures occurred at a median of 50 (range, 10–270) days after onset of AP, and were associated with a lower operative mortality of 15%. In this case of RAP, about 10 days after the first onset of AP, edema and thickening of the colon wall, but no colonic strictures, were observed on MDCT. At the onset of the third AP, approximately 120 days after the onset of the first AP, colon stenosis combined with bowel obstruction were observed on MDCT. Notably, a gradually decreased hemoglobin level and positive results for multiple fecal occult blood tests were observed at the onset of the third AP, suggesting that lower gastrointestinal bleeding should always raise a suspicion of colonic complication. Unfortunately, as this patient did not undergo a colonoscopic examination, no inferences can be drawn about the potential role of colonoscopic diagnosis for colonic complication induced by AP.

In summary, this case report provided a detailed overview of the management of the colonic stricture caused by RAP. Colonic complications are uncommon in severe AP, clinical recognition can be difficult, and attention should be paid to the occurrence of colonic complications when lower gastrointestinal bleeding occurs. Abdominal MDCT imaging can aid diagnose colonic stricture caused by RAP, and surgery is the mainstay of AP management. Future research should examine whether preserving colonic micro- or macrovascular perfusion reduces the risk of these complications.

Acknowledgments

None.

Footnote

Funding: This work was supported by the Senior Medical Talents Program for Young and Middle-Aged Individuals of Chongqing (No. YXGD202472).

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://qims.amegroups.com/article/view/10.21037/qims-24-2445/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patient for publication of this article and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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