Vascular penetration sign: dual-phase enhanced CT manifestations of atypical liver abscess caused by Klebsiella pneumoniae.

OBJECTIVES

The aim of this study was to investigate the multislice spiral computed tomography (MSCT) features of atypical liver abscesses caused by Klebsiella pneumoniae (KP).

METHODS

A retrospective review was conducted on patients with atypical KP-caused liver abscesses, as verified by biopsy or surgery, from October 2019 to December 2023. All patients underwent dual-phase enhanced CT scan, and MSCT findings were analysed.

RESULTS

Seventy-two patients (58.5 ± 12.3 years, 43 males, 29 females) with atypical KP-induced liver abscess and 115 lesions were identified. Vascular penetration was detected in twelve lesions, presenting as vascular thickening, indistinct margins, and irregular invasive alterations. Among them, three lesions were initially misdiagnosed as primary hepatic lymphoma (PHL). Additionally, 50 lesions exhibited imaging patterns such as the "honeycomb", "petal", or "cluster" signs, and 40 lesions showed "lesion shrinkage" sign. Transient abnormal enhancement in hepatic parenchyma was observed in 83 lesions.

CONCLUSION

Vascular penetration with inflammatory infiltration might be a crucial sign in the diagnosis of atypical liver abscess caused by KP; correctly recognising this sign could reduce misdiagnosis.

KEY POINTS: Question Early imaging diagnosis of atypical liver abscesses caused by Klebsiella pneumoniae is significant because microbiology or blood cultures are time-consuming and may delay appropriate treatment. Findings The vascular penetration sign was noted in some Klebsiella pneumoniae atypical liver abscesses and play a vital role in the diagnosis of this disease. Clinical relevance The newly discovered vascular penetration sign in this study is an important sign for identifying atypical liver abscesses caused by Klebsiella pneumoniae. Accurate identification of this sign facilitates early clinical diagnosis and diminishes the risk of misdiagnosis.