Table 1.

Differential diagnosis for needle tract seeding by HCC and imaging characteristics of each entity.

	Needle tract seeding by HCC	Soft tissue sarcoma	Metastatic squamous cell carcinoma
X-ray	Nonspecific soft tissue mass and bone erosion (if present) may be visible although most likely normal appearing radiographs
Ultrasound	Mixed echogenicity mass
CT	Soft tissue density mass which may contain hypodensity/necrosis and calcification
MRI	Variable T1 intensity, usually T2 hyperintense in relation to liver	Variable appearance, high (fat) and low (calcification) T1 and T2 signal. Hemorrhage may be present.	Variable appearance, may be T1 iso/hypointense and T2 moderately hyperintense
Enhancement pattern	Enhances strongly on arterial phase with progressive “washout” on venous and delayed phases	Enhances heterogeneously	Enhances heterogeneously; early enhancement
Scintigraphy	Intrahepatic HCC is typically positive with gallium scan	May concentrate thallium	Nonspecific findings
PET	Typically hypermetabolic, however, may be similar to liver FDG uptake