Hepatic TB and Fungal Infections

Michael P. Federle, MD, FACR

Brooke R. Jeffrey, MD

Key Facts

Terminology

Opportunistic infection of the liver (± other viscera), usually by fungal or mycobacterial organisms

Imaging

Best diagnostic clue: Multiple well-defined, rounded microabscesses in liver
Best imaging tool: CECT, US
Protocol advice
- MDCT: IV contrast at 2.5 mL/sec with < 2 mm collimation and 2.5 mm reconstruction interval
- MR: FLASH sequences
- Gadolinium enhancement required to detect very small lesions

Top Differential Diagnoses

Metastases
Lymphomatous/leukemic foci in liver
Biliary hamartomas
Caroli disease

Pathology

Originates from intestinal seeding of portal and venous circulation

Clinical Issues

Most common signs/symptoms
- Asymptomatic or abdominal pain and fever
- Erythematous papules on skin
Clinical profile: Immunocompromised patient recovering from neutropenia

Diagnostic Checklist

Rule out other “innumerable hypodense liver lesions”
Biopsy specimen for histology/microbiology

(Left) High-power view of hepatic miliary tuberculosis shows a granuloma with focal eosinophilic granular necrotic material

and several multinucleated giant cells

. (Courtesy J. Misdraji, MD.) (Right) Axial CECT of a woman with breast cancer, fever, and liver dysfunction demonstrates multiple small, low-density lesions

due to hepatic candidiasis. Metastases would uncommonly be so numerous and small.

(Left) Axial CECT in a patient undergoing chemotherapy for acute leukemia, now presenting with a fever, demonstrates fungal abscesses due to Candida. Note the multiple small (< 1 cm) lesions

in all lobes of the liver. (Right) Axial CECT of a 33-year-old woman with non-Hodgkin lymphoma presenting with a recent spike in temperature shows innumerable tiny hypodense lesions in the liver and spleen due to candidiasis. Lymphomatous parenchymal involvement is rarely detected as such small discrete lesions.

TERMINOLOGY

Definitions

Opportunistic infection of liver (± other viscera), usually by fungal or mycobacterial organisms

IMAGING

General Features

Best diagnostic clue
- Multiple well-defined, rounded microabscesses in liver

CT Findings

NECT
- Multiple small, hypodense lesions
- ± scattered areas of calcific density (healing phase)
CECT
- Biphasic CT may be more accurate than venous phase only
- Nonenhancing hypodense centers
- ± peripheral rim enhancement
- Central or eccentric “dot” felt to represent hyphae

Ultrasonographic Findings

Grayscale ultrasound
- 4 major patterns of hepatic candidiasis
  - Uniformly hypoechoic
    - Most common appearance (fibrosis and debris)
  - Echogenic
    - Scar formation
  - “Wheel within wheel”
    - Peripheral zone surrounds inner echogenic “wheel,” which surrounds central hypoechoic nidus (early stage)
  - “Bull’s eye”
    - 1-4 mm lesion with hyperechoic center surrounded by hypoechoic rim (neutrophil count returns to normal)
- After antifungal therapy: Lesions increase in echogenicity, decrease in size, often disappear altogether