Transverse colon carcinoma presenting with perforation and abscess formation

Clinical History

Middle-aged woman with unremarkable past medical history, suffering from acute upper abdominal pain. Physical findings of positive Murphy's sign, tender palpable mass and localized peritonitis in her right upper quadrant.
Laboratory changes indicating anaemia (haemoglobin 10.2 g/dL) and infection-inflammation (16.000 leukocytes/mmc, C-reactive protein162 mg/L).

Imaging Findings

Urgent unenhanced and post-contrast multidetector CT (Fig.1) showed a sizeable (approximately 7x6x5cm) fluid-attenuating mesocolic abscess collection with internal gas bubbles and characteristic rim-like peripheral enhancement, surrounded by prominent inflammatory fat stranding and associated with mild thickening of the adjacent peritoneal serosa. The abscess was adherent to a segmental, non-stratified circumferential thickening of the transverse colon with abrupt transition to uninvolved bowel and some associated diverticula. Two satellite lymphadenopathies were noted.
Laparotomic surgery confirmed an infected colonic mass which required subtotal colectomy with ileo-descending anastomosis. Pathology diagnosed moderately differentiated adenocarcinoma with transmural infiltration (pT2N1G2). After an uneventful postoperative course, the patient received adjuvant chemotherapy (capecitabine plus oxaliplatin).
Follow-up CT studies (Fig.2) showed normal postoperative status and disappearance of inflammatory changes. One year after surgery, the patient is free from local, nodal, hepatic or distant neoplastic recurrence.

Discussion

Background: in industrialized countries, most colorectal carcinomas (CRC) are currently detected before clinical symptoms (such as digestive bleeding, abdominal pain, altered bowel habits, weight loss, iron-deficiency anaemia) develop. However, particularly in elderly people nearly 25% of CRCs manifest as emergencies, the majority (>80% of cases) represented by bowel obstruction. Uncommon CRC presentations include perforation (10-15%), abscess formation (0.3-0.4%), haemorrhage, fistulization with urinary bladder or female genital organs in descending order of frequency [1, 2].
Neoplastic colonic perforation (NCP) at the site of CRC results from transmural invasion and tumour necrosis, is more frequent (approximately 60% of cases) at the descending and sigmoid colon, and may be either free or localised: the former type is more likely in the right and transverse colon. Abscesses may develop from NCP in the paracolic spaces or pelvic cavity, occasionally in extraperitoneal sites such as the retroperitoneum, iliopsoas muscles, abdominal wall and perirectal space [1, 3-7].
Clinical Perspective: NCP manifests with pain, generalized or localised peritonitis, palpable mass, fever, hypotension, altered mental state, laboratory signs of infection and anaemia [1, 3-7].
Imaging Perspective: As this case exemplifies, imaging appearances includes a pericolonic abscess or phlegmon, associated with pericolonic fat inflammatory stranding and with marked non-stratified or irregular segmental mural thickening. Involvement of a short colonic segment, an abrupt transition from normal to abnormal bowel wall, and presence of lymphadenopathy favour abscess-forming CRC over complicated diverticulitis or acute appendicitis [6-8].
Outcome: Diagnosis of perforated CRC impacts the surgical strategy and represents (similarly to positive resection margins) an indication for adjuvant chemotherapy. Stent decompression and laparoscopic surgery are contraindicated. Left-sided NCP is usually treated with Hartmann’s procedure or segmental resection with proximal defunctioning stoma. Resection without protective ileostomy is possible in right-sided NCP in absence of sepsis and peritonitis [1, 9].
The worse 5-year survival rate of NCP compared to uncomplicated CRC results from the combined effect of the higher incidence of locally advanced malignancy and distant metastases (53% stage IV, 37% IIIb, 10% IIIa) at presentation and the high perioperative mortality from sepsis which only recently dropped to approximately 20%. Howewer, with a correct diagnosis and successful resection, the prognosis of CRC with perforation and/or abscess formation follows that of unperforated CRC in same pathological stage [1, 3-5, 9, 10].
Take Home Message: Albeit rare, NCP should be considered in the differential diagnosis of intra-abdominal abscesses in CT studies performed in adults with acute abdomen [6-8].

Differential Diagnosis List

Final Diagnosis

Adenocarcinoma of transverse colon complicated by perforation and abscess formation

URL:	https://www.eurorad.org/case/13091
DOI:	10.1594/EURORAD/CASE.13091
ISSN:	1563-4086