Hairball and turquoise sign of Klebsiella liver abscess

A 72-year-old male came with complaints of fever, right upper quadrant pain, and loss of appetite for the past 3 days. His total leukocyte count was 21460 cells/mm³ with neutrophilia (88%). Contrast-enhanced computed tomography abdomen showed a large hypodense abscess with a tangled pattern of blurring amorphous hair-like content in the abscess fluid (Hairball sign) shown in Figure 1, and irregular margins and multiple enhancing incomplete branching internal septations in the right lobe of liver (Turquoise sign) shown in Figure 2. Ultrasound-guided abscess drainage yielded ∼100 mL of pus, following which a pigtail catheter was inserted. Pus and blood culture revealed Klebsiella pneumoniae.

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Figure 1:

Axial section of contrast-enhanced CT abdomen shows a large hypodense abscess with a tangled pattern of blurring amorphous hair-like content seen in the abscess fluid in the right lobe of liver (white arrows - hairball sign). CT: Computed tomography.

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Figure 2:

Coronal reformat of contrast-enhanced CT abdomen shows a large hypodense abscess with irregular margins, incomplete branching internal septations (black arrows - turquoise sign), and tangled pattern of blurring amorphous hair-like content seen in the abscess fluid in the right lobe of liver (white arrows - hairball sign). CT: Computed tomography

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Hairball sign is not present in all Klebsiella liver abscesses (KLA) but has a high predictive value.¹ The amorphous hair-like content is likely due to the highly invasive nature of the organism and consequent earlier clinical presentation during the immature stage of the abscess. Hairball-like appearance most likely represents a mixture of immature pus and debris.^1,2 Incomplete, finely arborizing septations within the abscess are called the turquoise sign, due to their resemblance to the morphological appearance of the turquoise mineral. Turquoise sign occurs due to septal breakages in the abscess cavity owing to the highly invasive nature of the organism and has high specificity (96.4%) and positive predictive value (85.7%) for KLA.³ Turquoise sign, hairball sign, air- fluid level and lack of rim enhancement, higher frequency of bacteremia, infection at other sites and absence of underlying biliary disease are features suggestive of KLA.^1,2 When at least three of the following four signs (thin wall, necrotic debris, presence of metastatic infection, and the absence of underlying biliary disease) are present, a diagnosis of KLA has a specificity of 98.6%.² As KLA shows a higher propensity for portal or hepatic vein thrombophlebitis, they need to be recognized early to avoid hematogenous spread and its complications.