Intestinal nonrotation in an adult with colon cancer

A 39-year-old patient with no notable medical history presented with right upper quadrant pain, which required treatment with level 2 analgesics. The primary care physician ordered an abdominal ultrasound performed outside the hospital, which revealed multiple hypoechoic hepatic lesions. The patient was referred to us for a triphasic CT scan to further characterise these lesions.

We performed a triphasic abdominal angio-CT to characterise the hepatic lesions. The scan revealed multiple spontaneously hypodense hepatic lesions with poorly defined margins, which enhance peripherally during the portal phase, suggesting suspicious secondary lesions. Upon searching for a primary, there was a demonstrated focal segmental irregular colonic wall thickening at the junction of the descending and sigmoid colon associated with perilesional fat stranding and round-shape adenomegaly of the mesocolon.

In analysing the remaining colon, the small bowel was mainly located in the right hemiabdomen and the cecum to the left of the midline, with the remaining large bowel in the left hemiabdomen. Additionally, the superior mesenteric vein was positioned to the left of the superior mesenteric artery. These findings were consistent with intestinal nonrotation associated with a primary colorectal malignancy metastatic to the liver.

The patient underwent a colonoscopy with biopsies, which concluded with a diagnosis of tubulovillous adenocarcinoma.

The simultaneous diagnosis of gastrointestinal malignancy and intestinal malrotation in adults is uncommon, although case reports are available [1–6]. The detection of malrotation in adults can be challenging as many remain asymptomatic and are incidentally diagnosed upon presentation for alternate medical issues. Nonrotation is the most common subtype of intestinal malrotation in adults, detected in about 0.15% of patients undergoing computed tomography (CT) colonography [1].

In nonrotation-type malrotation, the small intestine is confined to the right hemiabdomen, the large bowel is positioned in the left abdomen, and the duodenum descends straight down to join the jejunum to the right of the midline [2]. Since 2000, there have been 49 cases of colorectal cancer diagnosed in patients with intestinal malrotation. Amongst these 49 patients, 41 cases of right-sided colon cancer have been reported, with most being of the nonrotation type [3].

Anatomical variations due to malrotation can create challenges in diagnosing and treating cancer due to unusual positioning of the superior mesenteric artery and vein, as well as abnormal positioning of the bowel [4]. Surgeons must be well versed in these variations to reduce risks during surgery. Preoperative imaging utilising CT and ultrasound play a crucial role in detecting these anomalies for improved surgical planning.

The potential association between malrotation and an increased risk of cancer remains an area of investigation. It has been suggested that chronic inflammation of the bowel due to chronic semi-obstruction associated with malrotation may contribute to an increased risk of developing cancer [5,6].

This hypothesis warrants further investigation, particularly in understanding whether malrotation could be considered a premalignant condition, thereby influencing follow-up strategies for patients diagnosed with this anomaly.

All patient data have been completely anonymised throughout the entire manuscript and related files.