Dysplastic liver nodules

Dysplastic liver nodules are focal nodular regions (≥1 mm) without definite evidence of malignancy.

Epidemiology

They have been found in cirrhotic patients with a prevalence of 14% (size >1.0 cm) to 37% (size >0.5 cm) ².

Associations

• cirrhosis

Pathology

Dysplasia indicates:

• nuclear atypia
• increased fat or glycogen in the cluster of dysplastic cells

Classification

They are broadly divided depending on the presence of cytologic and architectural atypia ^2,4:

• low-grade: resemble regenerative nodule
• high-grade: resemble well-differentiated hepatocellular carcinoma (HCC)
  • atypia is insufficient to establish a diagnosis of HCC
  • may exhibit clone-like features

Radiographic features

Ultrasound

Cirrhotic changes are present but the nodules may not be visualized on ultrasound. A few cases have shown hypo- and hyperechoic nodules and the echogenicity relates to the fat content in the nodule.

CT

Usually hypoattenuating, however, they may be iso- or hyperattenuating to the hepatic parenchyma.

• multiphase contrasted images: they may show early arterial uptake but the contrast does not wash out on delayed phase (unlike HCC)

MRI

• T1: although the signal intensity may vary broadly, most of them have high T1 signal 
• IP-OOP: shows fat accumulation characterized by signal drop on the out-of-phase sequence
• T2: iso- to hypointense
• DWI: no restricted diffusion
• ​T1 C+ (Gd)
  • high-grade nodules show early contrast enhancement without washout on delayed phase
• T2* C+ (SPIO)
  • low-grade nodules appear hypointense ¹³

Treatment and prognosis

They are considered premalignant and hence follow-up is necessary. Percutaneous ablation therapy can be considered ⁹.

Differential diagnosis

• regenerative nodule
• early hepatocellular carcinoma
  • increased T2 signal
  • restricted diffusion 
  • washout on multiphase postcontrast imaging