Post-Operative Fever and a Liver Lesion: Abscess or Tumour?
A 61-year-old woman undergoes a laparoscopic cholecystectomy for symptomatic gallstones. On day 6 she develops fever to 38.9°C, right upper quadrant pain, and rigors. White cell count is 17.2 × 10⁹/L and CRP is 210 mg/L. Blood cultures grow a Gram-negative organism. A CT shows a 4.5 cm low-attenuation lesion in segment IVb with a thick enhancing rim and surrounding fat stranding, plus a small amount of fluid at the surgical bed. She has a history of diverticular disease and a 12-pack-year smoking history, and her mother had colon cancer at 62. The surgical team asks whether this could be a liver metastasis and whether the lesion needs biopsy.
1. Explain how the clinical and imaging findings point toward abscess versus metastasis, and identify the features that are non-specific.
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The timing, fever, rigors, leucocytosis, raised CRP, and positive blood cultures all strongly favour an infective process, and the CT appearance of a thick enhancing rim with surrounding fat stranding in the surgical bed after cholecystectomy is typical of a pyogenic liver abscess, likely related to biliary instrumentation or a small bile leak. Metastasis would not usually present with rigors and positive blood cultures, and the rim enhancement of an abscess can mimic the peripheral enhancement of a metastasis. Non-specific features include the low-attenuation centre, which occurs in both necrosis and pus, and the surrounding fat stranding, which can accompany tumour inflammation. The history of diverticular disease and the family history of colon cancer raise the possibility of a colorectal primary, but these are background risks rather than evidence for this lesion. The key judgement is that the clinical syndrome and the surgical context make abscess far more likely, and the lesion should be treated as infective first.
2. What would you do next, and when would biopsy or further imaging be justified?
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The immediate priority is source control and antibiotics guided by blood cultures, with ultrasound or CT-guided drainage of the collection if it is accessible and the patient does not improve rapidly. A small amount of surgical bed fluid may not need drainage, but the 4.5 cm lesion with rigors and bacteraemia usually warrants drainage for both treatment and microbiology. Repeat imaging in 48-72 hours is appropriate to confirm resolution or identify a bile leak or undrained collection. Biopsy is not indicated at presentation because of the risk of seeding and because the diagnosis is clinically secure. If the lesion fails to resolve after adequate drainage and antibiotics, if cultures are negative, or if imaging shows an atypical solid component, then biopsy or further evaluation for malignancy becomes justified. A colonoscopy could be considered later given the family history, but it is not the immediate priority.
3. Six weeks later the lesion has shrunk but a residual 1.8 cm rim-enhancing focus persists. How does this change your approach?
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A residual rim-enhancing focus after treated abscess can represent a resolving cavity, granulation tissue, or a small undrained collection, but persistent rim enhancement at six weeks should prompt reassessment rather than simple observation. I would compare with the earlier CT to confirm shrinkage and assess whether the rim is thinner and less nodular, which favours resolution. If the patient is well with normal inflammatory markers, short-interval imaging at 3 months is reasonable. If there is any solid nodular component, growth, or rising tumour markers, I would proceed to MRI with hepatobiliary contrast and consider biopsy, because a necrotic metastasis can mimic a resolving abscess. The family history of colon cancer and the smoking history support a lower threshold for colonoscopy and for tissue diagnosis. The key judgement is that persistent imaging abnormality after infection requires a defined follow-up plan and a low threshold for biopsy if the morphology is atypical.