Sigmoid diverticulitis mimicking colorectal cancer: A case report

Abstract

Sigmoid diverticulitis is a common gastrointestinal condition, but presentation with intestinal obstruction closely resembling colorectal malignancy is rare and poses a significant diagnostic challenge, particularly in resource-limited settings. A 56-year-old man presented with progressive abdominal distension, feculent vomiting, and intermittent rectal bleeding, and computed tomography demonstrated features of large bowel obstruction at the sigmoid colon suspicious for malignancy. Emergency laparotomy with oncologic resection was performed, and histopathological analysis confirmed benign sigmoid diverticulitis without evidence of cancer. This case highlights the substantial diagnostic overlap between diverticulitis and colorectal malignancy on imaging, underscoring the limitations of radiology alone in distinguishing benign from malignant disease. Histopathological confirmation remains essential to guide definitive management, and adherence to oncologic surgical principles ensures safe outcomes when malignancy cannot be excluded preoperatively, especially in low-resource settings.

Introduction

Sigmoid diverticulitis, characterized by the inflammation of diverticula in the sigmoid colon, is a common gastrointestinal disorder, particularly in individuals over the age of 50. Its clinical presentation varies widely, ranging from mild localized abdominal pain to severe complications such as abscess formation, perforation, fistula development, and bowel obstruction [1]. In rare cases, diverticulitis may present with intestinal obstruction (IO), mimicking colorectal cancer (CRC) in its clinical and radiologic manifestations, which can create significant diagnostic challenges [2].

Globally, the prevalence of diverticular disease is influenced by dietary habits, lifestyle, and socioeconomic factors [3]. It is more commonly seen in Western countries, where low dietary fiber intake is a well-recognized risk factor [4]. In contrast, its prevalence in Africa and Asia remains lower, although it is gradually increasing due to urbanization and dietary changes. Meanwhile, CRC, a major cause of cancer-related mortality, continues to impose a significant public health burden, particularly in low- and middle-income countries (LMICs) where late-stage presentation is common due to limited access to diagnostic and screening services [5,6].

The clinical overlap between sigmoid diverticulitis and CRC stems from shared symptoms such as abdominal pain, changes in bowel habits, and rectal bleeding [7]. IO caused by sigmoid diverticulitis is an uncommon occurrence, reported in only 10%-25% of complicated cases requiring surgical intervention [8]. The pathophysiology involves chronic inflammation and fibrosis, which lead to stricture formation and luminal narrowing, mimicking a neoplastic process. On imaging, particularly computed tomography (CT), diverticulitis-associated strictures may exhibit features indistinguishable from malignancy, necessitating histopathological examination for a definitive diagnosis [9].

CT remains the diagnostic modality of choice for evaluating acute diverticulitis and its complications, providing high sensitivity for identifying mural thickening, pericolonic fat stranding, and abscesses. However, its limitations in differentiating between benign and malignant colonic lesions underscore the importance of a multidisciplinary approach [10]. Surgical intervention, such as oncologic resection with adequate margins, is often warranted in cases where malignancy cannot be excluded preoperatively.

This case report presents a rare instance of sigmoid diverticulitis mimicking CRC in a 56-year-old male with IO. The clinical presentation, radiologic findings, and intraoperative findings strongly suggested malignancy, but histopathologic evaluation confirmed benign disease. This case highlights the importance of considering diverticulitis as a differential diagnosis in patients presenting with colonic obstruction, especially in LMIC settings where advanced diagnostic resources may be limited. It also underscores the value of postoperative follow-up, including colonoscopy and carcinoembryonic antigen (CEA) testing, to rule out synchronous or metachronous colorectal malignancies and to ensure optimal patient outcomes.

This manuscript was prepared following the CARE guidelines (https://www.care-statement.org).

Case presentation

A 56-year-old male was referred to our centre with a progressive abdominal pain for 7 days which was associated with progressive abdominal distention and loss of appetite. This was followed by post prandial vomiting of which initially was bilious then worsened to foul-smelling fecal-like with associated obstipation. Two weeks prior to the onset of his symptoms he had a brief history of passing mucoid-like lose stools which were blood-stained on 2 occasions, otherwise denied past history of changes in his bowel habits or unintentional weight loss. He denied any past medical history of chronic illness like peptic ulcers, hypertension or diabetes mellitus. He reported to be a social drinker but not a smoker. There was no familial history of malignancies or bleeding disorders.

On initial examination he was fully conscious and oriented to person, place and time. He was not pale nor jaundiced, mildly dehydrated with no peripheral lymphadenopathy. His vital signs were within normal range and was saturating at 98% on room air. His abdomen was globally distended, inverted umbilicus with no visible peristalsis. There was no obvious organomegaly on palpation and no inguinal hernia. On percussion the abdomen had a hypertympanic note with no shifting dullness. His bowel sounds were reduced in frequency and pitch. On rectal examination, he had a normal anal verge and tone with no palpable masses per rectum and a grade-2 prostate. Other systems were essentially normal.

His lab results revealed a normal CBC with a hemoglobin of 16 g/dl, serum electrolytes and BUN within normal range, however, Hepatits B surface antigen was positive. CT-scan of the abdomen showed a 9 cm long mural thickening of the sigmoid colon with proximal colon distention suggestive of obstruction at sigmoid colon (Fig. 1). He was then taken for an emergency laparotomy where intra-operatively the ileum and colon were distended until the sigmoid with an 8 cm section of sigmoid wall thickening causing constriction. The liver, omentum, bowel mesentery and spleen were grossly normal appearing. There was about 100 millilitres of clear straw-colored ascites which on analysis was transudate. An oncologic resection of the sigmoid segment was performed with 8 cm margins, and a Brooke–Hartmann colostomy was fashioned, as frozen section analysis was unavailable at our centre. Primary anastomosis was not undertaken to minimize operative time, given the significant discrepancy between the proximal and distal bowel loops, the risk of anastomotic breakdown due to bowel edema from the 7-day history of abdominal symptoms, and the potential need for a subsequent resection. The specimen was submitted for histopathological examination, which confirmed sigmoid diverticulitis with no histological evidence of malignancy, including in the 8 mesenteric lymph nodes assessed (Fig. 2).

Fig. 1.

CT scan (A: coronal, B: axial) showing mural wall thickening of the sigmoid colon measuring 9 cm in length causing stenosis of sigmoid lumen and associated dilatation large bowel, features suggestive of large bowel obstruction secondary at sigmoid colon (arrow). Minimal ascites seen.

Fig. 2.

(A) Intestinal segment with thickened wall observed from the serosa and demonstrated on cut surface and (B) The section shows benign colonic mucosa herniating through the muscularis propria with associated reactive and mild hyperplastic changes of the mucosa and thickening of the muscularis propria (H&E staining).

The patient faired well postoperatively in the general surgery ward with analgesia, antibiotics, oral vitamin C and Zinc supplements. He developed superficial surgical site infection whereby was managed conservatively with honey dressing and antibiotics according to the culture and sensitivity report. He was reviewed by the medical team and initiated on antiviral therapy for chronic hepatitis B infection. He was discharged 28 days after surgery with a body mass index of 23 kg/m². At surgical outpatient review 2 weeks later, he was clinically well and was advised to continue follow-up in the medical outpatient clinic for ongoing hepatitis B management. During consecutive surgical follow up, colonoscopy was done which ruled out any lesions on the colon and carcinoembryonic antigen (CEA) was in normal ranges in 2 occasions. Twelve months later, the Hartmann’s colostomy was reversed with an uneventful postoperative recovery and discharge on day 3 post operatively with a BMI of 23.9 kg/m².

Discussion

Sigmoid diverticulitis presenting with intestinal obstruction (IO) is an uncommon clinical scenario, with significant diagnostic challenges due to its similarity to colorectal cancer (CRC) in both clinical and radiologic presentations [[11], [12], [13]]. The incidence of IO secondary to diverticulitis is reported in 10%-25% of complicated cases requiring surgical intervention, primarily due to stricture formation from chronic inflammation and fibrosis [4]. Globally, diverticulosis becomes increasingly common with age—affecting ∼10% of adults <40 years, ∼50%-60% by age 60, and >60%-70% by the eighth decade—and annual diverticulitis incidence in high-income settings is roughly 150-180 per 100,000 persons [14]. This overlap in clinical presentation often complicates the preoperative diagnosis, particularly in resource-limited settings where advanced diagnostic tools such as endoscopic biopsy or molecular imaging are often unavailable. Although diverticulitis accounts for a minority of large-bowel obstructions overall (∼3%-4%), fixed sigmoid strictures from chronic inflammation—as in this patient—are a recognized cause and often necessitate resection [15].

In this case, the patient presented with symptoms suggestive of colonic obstruction, including abdominal distension, progressive pain, vomiting, and episodic hematochezia. These features, coupled with CT findings of mural thickening and colonic distension, raised a high suspicion for malignancy. Computed tomography (CT), while the preferred diagnostic modality for acute diverticulitis, has inherent limitations in differentiating between benign inflammatory strictures and malignant neoplastic lesions. The diagnostic sensitivity of CT for diverticulitis is high, ranging from 73% to 92%, but its specificity in excluding malignancy remains low, necessitating histopathological confirmation [16]. This diagnostic ambiguity is well-recognized in the literature; even high-quality CT cannot reliably distinguish chronic inflammatory strictures from CRC, and definitive exclusion of malignancy typically requires endoscopic/histologic assessment where available [17].

The surgical management in this case, which involved an oncologic resection with Hartmann’s procedure, was appropriate given the clinical uncertainty and the potential risk of malignancy. Oncologic principles dictate that resection with adequate margins is warranted when malignancy cannot be excluded preoperatively, a practice consistent with international guidelines [18]. Histopathological analysis ultimately confirmed the benign nature of the lesion, highlighting the critical role of pathology in resolving diagnostic ambiguity. Reported recurrence after definitive resection for diverticular stricture is low (<5%), supporting the durability of an oncologic-principled approach when cancer cannot be excluded [19].

This case also emphasizes the broader challenges in managing sigmoid diverticulitis and CRC in low- and middle-income countries (LMICs). Diverticular disease, traditionally more prevalent in Western countries, is increasingly observed in LMICs due to urbanization, aging populations, and dietary changes [20]. Recent African endoscopy series report diverticular disease in ∼9–17% of colonoscopies—eg, Ghana ∼8.9%, South Africa ∼13.5%, and Cameroon ∼17%—suggesting a rising burden compared with older reports that described rarity in urban African populations [21]. Simultaneously, CRC remains a significant cause of morbidity and mortality, with late-stage presentation being a common feature in LMICs due to limited access to diagnostic and screening services [22]. Compared with these regional data, our patient’s presentation with a sigmoid stricture and IO mirrors patterns seen in Western cohorts (where left-sided/sigmoid disease predominates) and underscores how epidemiologic transitions in Africa are narrowing historical differences in anatomic distribution and complication profiles [23].The overlap between these 2 conditions necessitates a comprehensive approach to diagnosis and management, integrating radiologic, surgical, and pathological expertise.

Postoperative care in this case was noteworthy, with conservative management of a superficial surgical site infection using honey dressing, an evidence-based and cost-effective intervention particularly suited to resource-limited settings [24]. Rigorous follow-up with colonoscopy and carcinoembryonic antigen (CEA) testing excluded synchronous or metachronous malignancies and ensured optimal patient outcomes. The successful reversal of the Hartmann’s colostomy after 12 months further demonstrated the long-term viability of the surgical strategy employed. From a population lens, the increasing incidence of diverticulitis in younger adults has been documented internationally, reinforcing the need for context-appropriate diagnostic pathways in LMICs where younger patients may present atypically and advanced diagnostics are limited [25].

This case highlights the pressing need to improve diagnostic capabilities in LMICs to differentiate between diverticulitis and CRC more effectively. Enhanced access to endoscopic biopsy, CT colonography, and multidisciplinary diagnostic teams could significantly reduce the reliance on extensive surgical interventions for benign conditions. Furthermore, investments in preventive healthcare, such as promoting high-fiber diets and implementing CRC screening programs, are critical to reducing the burden of both diverticular disease and CRC in these regions. Given the substantial age-related prevalence of diverticulosis and the nontrivial annual incidence of diverticulitis, scalable strategies that pair diet and screening with timely access to colonoscopy/biopsy could reduce unnecessary oncologic resections for benign strictures, particularly in resource-limited hospitals

Conclusion

This case demonstrates the diagnostic complexity and therapeutic challenges of sigmoid diverticulitis presenting as IO, mimicking CRC. It underscores the importance of adhering to oncologic surgical principles in the absence of definitive preoperative diagnosis and the critical role of histopathological analysis in guiding postoperative management. In LMICs, where the burden of both diverticular disease and CRC is rising, strengthening diagnostic infrastructure, promoting multidisciplinary collaboration, and implementing preventive strategies are essential to improving patient outcomes. Enhanced access to advanced diagnostic tools and evidence-based management protocols will be pivotal in addressing these challenges effectively.

Patient consent

The patient provided written informed consent for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal on request.

Authors’ contributions

WN and JL conceptualized and drafted the manuscript. PA and JL reviewed the medical records. PA reviewed and reported the histology slides and analysis. All authors have read and approved the final script. All authors attest that they meet the current ICMJE criteria for Authorship.