Massive porto-mesenteric venous thrombosis in Crohn's disease

Clinical History

Middle-aged woman with long-standing fistulizing and stricturing ileo-colonic Crohn's disease currently on biologic (adalimumab) therapy, hospitalized because of alternating diarrhoea and constipation, recurrent febrile episodes over a few months. Physically found malnourished with pelvic tenderness.
Past surgical history included ileocaecal resection (1998), stricturoplasties (2006), segmental ileal resection and adhesiolysis (2014).

Imaging Findings

Two years earlier, before the latest surgery CT (Fig. 1) showed thickened distal ileum with mucosal hyperenhancement, hypertrophied mesenteric fat with vascular engorgement ("comb sign") consistent with active Crohn's disease (CD), causing mild upstream bowel dilatation; at that time the portal-mesenteric venous system was patent.
Four months earlier, the latest colonoscopy reported impassable stenotic ileocolonic anastomosis, absence of active colonic mucosal lesions.
Currently, two years after ileal resection, emergency CT (Fig. 2) showed obstructive thrombosis of the main portal vein, dilated left lobar branch and mesenteric venous system, with ancillary findings of heterogeneous liver perfusion and initial formation of tortuous venous collaterals at the porta hepatis.
Colonoscopy confirmed active ileo-colonic CD, strictured and ulcerated anastomosis. After medical treatment including anticoagulation, follow-up CT (Fig. 3) showed persistently thrombosed portal and mesenteric venous system with decreased calibre, and progression of dilated venous collaterals indicating portal cavernomatous transformation.
Two months later, elective surgery including adhesiolysis and limited ileal resection was performed.

Discussion

Chronic inflammatory bowel diseases (IBD) such as Crohn’s disease (CD) and ulcerative colitis are associated with a well-recognized risk of thromboembolic events (TEEs), approximately three times higher than that of the general population with 6.3% per 1000 person/years incidence rate. The multifactorial IBD-associated hypercoagulability involves abnormalities of fibrinolysis, coagulation cascade and platelets activation; additionally one-third of patients also have inherited prothrombotic conditions such as hyperhomocysteinaemia [1-4].
TEEs are often (77% of cases) encountered in outpatients, commonly but not invariably (69%) in clinically active CD, and may involve the deep veins of the extremities and pulmonary circulation, or other uncommon sites. Among the latter, portal-mesenteric venous thrombosis (PMVS) of variable entity has been reported in up to 28.9% of patients with CD, and may be acute, chronic, or combined. Unfortunately, symptoms of PMVS are usually absent, limited or nonspecific, therefore incidental imaging detection is common (40% of cases) particularly in the setting of acute CD exacerbations [1, 5, 6].
Albeit colour Doppler ultrasound represents a practical screening modality, PVMS is generally detected at contrast-enhanced CT or MRI as partial or complete filling defects, more commonly peripheral rather than central, frequently causing venous dilatation. PVMS is significantly associated with mural thickening, ascites, mesenteric lymphadenopathy and hypertrophy, but not with abscesses and fistulas. Despite 95% sensitivity, PVMS is often overlooked at initial CT interpretation. Since PVMS is associated with considerable morbidity and with subsequent need for surgery, the coscious radiologists should scrutinize emergency or elective (such as CT- or MR-enterography) cross-sectional imaging studies for possible portal-mesenteric thrombi [1, 5-7].
The key differential diagnosis is the rare but threatening septic pylephlebitis, secondary to ascending bacterial infection from the gastrointestinal tract during abdominal or pelvic infections or recent surgeries, which is confirmed by blood cultures and suggested at imaging by ring enhancement of the vein wall, gas in or adjacent to the thrombus, and abscess formation from intrahepatic seeding. Alternatively, PVMS may occur in patients with cirrhosis, myeloproliferative disorders, inherited and acquired hypercoagulable states including oral contraceptives [7-10].
In PVMS heparin anticoagulation followed by warfarin achieves recanalization in approximately 65% of patients. As this case exemplifies, delayed diagnosis or therapy failure lead to chronic cavernous transformation with development of hepatopetal collaterals at the porta hepatis to bypass the obstructed vein, with associated portal hypertension [5, 6].

Differential Diagnosis List

Final Diagnosis

Portal and mesenteric venous thrombosis. Crohn's disease.

URL:	https://www.eurorad.org/case/13904
DOI:	10.1594/EURORAD/CASE.13904
ISSN:	1563-4086