Persistent fever and lumbar pain

Clinical History

A 70-year-old woman presented to the ER with fever and intense lumbar pain. Laboratory tests revealed mild leukocytosis (11000/mm3) and microhaematuria. Abdominal/renal ultrasounds were unremarkable. She was discharged from hospital with a pyelonephritis diagnosis.
18 days later she returned because of maintained fever and loss of appetite. She denied other symptoms.

Imaging Findings

Abdominal and pelvic contrast-enhanced CT examination was then performed showing a non-enhancing low-attenuation thrombus within the lumen of the superior mesenteric vein extending to the portal vein without complete occlusion of this vessel with thickening and densification of the vessels walls.
Additionally there was evidence of fat stranding in the retrocaecal area with thickening and enhancement of the appendiceal wall and mild lymph node enlargement in the ileocaecal area.

Discussion

Pylephlebitis or septic thrombophlebitis of the portal system is a rare condition with a high mortality rate (around 30%) [1].
It is usually secondary to an intraabdominal infection either in the region drained by the portal system or in structures contiguous to the portal vein, but it may also occur in hypercoagulable states, trauma or neoplastic disorders. [2, 3]
Pylephlebitis usually begins with thrombophlebitis of the small veins that drain the infected area [4], extending gradually into larger vessels and ultimately leading to septic thrombophlebitis of the mesenteric vein, which can extend further to involve the portal system. [2]
The diagnosis of pylephlebitis requires the demonstration of portal vein thrombosis, usually accompanied by bacteraemia in a patient with fever. A high degree of suspicion is necessary, because its clinical presentation is nonspecific including abdominal pain, diarrhoea, jaundice and hepatomegaly.
Although diverticulitis is the most common aetiology, it is also a known complication of appendicitis, with an incidence of 0.05% for acute appendicitis and 3% for ruptured appendicitis [1].
As far as appendicitis is concerned unusual presentations, as the one described, with lumbar rather than right lower quadrant pain, most likely occur in elderly people or when the appendix is in an atypical location, delaying the correct diagnosis. Chronic appendicitis refers to pain of at least 3 weeks duration and CT findings are generally indistinguishable from those of early acute appendicitis. [5]
Contrast enhanced CT is the most reliable initial diagnostic choice because it can simultaneously reveal the thrombus, detect the primary source of infection and identify possible complications. CT findings may also include transient hepatic parenchyma attenuation differences and intrahepatic abscess.
Ultrasound with Doppler might also be useful as it can reveal echogenic material in the lumen of the portal vein corresponding to the thrombus. [4]
MR is generally not used since the previous methods usually give the diagnosis.
Early diagnosis and prompted treatment with broad-spectrum antibiotics are crucial for favourable prognosis. The use of anticoagulation and fibrinolysis is not consensual. [4]
Patients may completely recover, with recanalisation of the vessel after successful treatment of the underlying sepsis, or they may develop cavernous transformation of portal vein. [6]
Taking into account the clinical history and the imaging findings a diagnosis of pylephlebitis associated with chronic appendicitis was made in the reported case. The patient was treated medically with anticoagulation and meropenem for 14 days with good clinical evolution.

Differential Diagnosis List

Final Diagnosis

Pylephlebitis associated with appendicitis

URL:	https://eurorad.org/case/9807
DOI:	10.1594/EURORAD/CASE.9807
ISSN:	1563-4086