A 71-year-old Asian Man With a “Honeycomb” Liver Abscess

QUESTION

A 71-year-old man with poorly controlled diabetes mellitus who lives in Singapore presented to the emergency department with 2 weeks of lethargy and fever. On examination, he was febrile at 39.2°C but hemodynamically stable. He was lethargic but not toxic-looking. The rest of the physical examination was unremarkable. Laboratory studies were notable for elevated white cell count (13.0 × 10³/µL) and C-reactive protein (84.3 mg/L). His liver function test showed elevated alkaline phosphatase (129 U/L) and gamma-glutamyl transferase (118 U/L) but normal transaminases. There was no growth on all 3 sets of blood cultures. Contrast-enhanced computed tomography (Figure 1) and magnetic resonance imaging (Figure 2) demonstrated a hepatic mass in the bare area with rim-enhancing peripheral cystic foci and a central solid-looking area with a “honeycomb” appearance. There was transdiaphragmatic extension of the hepatic lesion along the inferior vena cava (Figure 3, bottom arrow). Necrotic right hilar and paratracheal lymph nodes were also observed (Figure 3, top arrow). Pus aspirated from the ­hepatic lesion under targeted ultrasound eventually grew a gram-negative bacterium. What is the most likely diagnosis?

DIAGNOSIS

Disseminated Melioidosis (Liver Abscess, Hilar and Paratracheal Lymph Nodes)

Cultures from the pus aspirated from the liver abscess eventually grew Burkholderia pseudomallei. The patient was started on intravenous ceftazidime with resolution of his fever and improvement in his inflammatory markers. Surgical drainage of the abscess was considered but not performed because the patient had improved on antibiotic treatment alone, and surgery was challenging due to the proximity of the liver abscess to the inferior vena cava.

Teaching Point

B pseudomallei, the agent responsible for melioidosis, is a facultative intracellular gram-negative bacterium endemic to Asia and Northern Australia [1]. Risk factors for melioidosis include diabetes, alcohol use disorder, chronic kidney disease, and soil exposure [2, 3]. Clinical manifestations of melioidosis are protean and include fulminant sepsis, pneumonia, encephalomyelitis, and abscess formation in the spleen, liver, genitourinary tract, and skin and soft tissue [3].

Multiseptate and multiloculated liver abscesses with a characteristic “honeycomb” appearance have been described for large B pseudomallei liver abscesses [4–6]. Khiangte et al analyzed 40 culture-proven B pseudomallei liver abscesses that are ≥ 2 cm. Sensitivity of the honeycomb sign for B pseudomallei liver abscess is 85% (95% confidence interval [CI], 70–94) [6]. If abscess size is ≥ 3 cm, the sensitivity is 91% (95% CI, 77–98) [6]. In the setting of relevant epidemiological exposures, melioidosis should be considered as a differential in patients who present with honeycomb liver abscesses, particularly when splenic abscesses are also present [7]. It is important to note that melioidosis can have a long latency period [8]. Cases of B pseudomallei reactivation have been reported in Vietnam War veterans up to 29 years from last residence in a melioidosis endemic area [8, 9]. Hence, when a honeycomb liver abscess is encountered in places where melioidosis is not endemic, a comprehensive travel history will be crucial to identify remote exposures to B pseudomallei and direct diagnostic testing. The specificity of the honeycomb sign for B pseudomallei liver abscesses is only around 75% [6]. Apart from B pseudomallei, Klebsiella pneumoniae [10], Escherichia coli [11], and Mycobacterium tuberculosis [12, 13] have also been reported to cause honeycomb liver abscess. Although a honeycomb liver abscess on imaging is suggestive of melioidosis, it is not pathognomonic. Efforts should be made to obtain a definitive microbiological diagnosis through cultures of clinical specimens (eg, blood, liver abscess aspirate) so the appropriate treatment may be rendered.

When epidemiological risk factors are present, empirical antibiotics that are active against B pseudomallei such as intravenous ceftazidime should be empirically initiated while diagnostic evaluation is under way because mortality rate, particularly in those presenting with fulminant sepsis, can be high [3]. B pseudomallei are intrinsically resistant to penicillin, ampicillin, and first- and second-generation cephalosporins. The main therapeutic options for melioidosis include ceftazidime [14], meropenem [15], imipenem [16], and trimethoprim-sulfamethoxazole [17], depending on the phase of treatment. Naturally occurring resistance is uncommon with ceftazidime and has not been reported with carbapenems, which retain activity against B pseudomallei isolates with decreased susceptibility to ceftazidime [18].

Notes

Financial support. The authors declare that no funding was received for this work.

References

Author notes