Characteristics of common solid liver lesions and recommendations for diagnostic workup

Table 1 Clinical differential diagnosis of the most common liver masses

	Cirrhotic liver	Common lesions	Non-cirrhotic liver	Common lesions
Malignant mass	Hepatocellular carcinoma	a,d	Metastasis	a,b
	Cholangiocarcinoma		Well differentiated HCC
	High grade dysplastic nodule		Fibro lamellar HCC	a,b,c,g
	Lymphoma		Cholangiocarcinoma
	Metastasis (exceptional)		Hemangio-Endothelioma	g
			Lymphoma
			Melanoma
			Neuroendocrine tumor	a
			Sarcoma (angiosarcoma,leiomyosarcoma)	g
Benign mass	Low grade dysplasia	d	Hemangioma	b
	Focal fatty liver		Focal nodular hyperplasia (FNH)	a,b
	Hemangioma		Hepatic adenoma (HA)	a,b
	Hepatic adenoma	g	Nodular regenerative hyperplasia	b,f
			Partial nodular transformation	e,f
			Focal fatty infiltration	c,e
			Bile duct adenoma

a: Hyper vascular liver tumor; b: Tumors that are extremely rare in cirrhosis but relatively frequent in healthy normal liver; c: Tumors frequent in the left lobe; d: Mainly in cirrhosis; e: Equally found in cirrhotic and non cirrhotic; f: Clinically mimics cirrhosis; g: Extremely rare tumors.

Table 2 Accuracy and key features of imaging techniques in the diagnosis of most common liver masses

	US-US doppler, contrast ultrasound	Triphasic CT	MRI	PET SCAN	CT-angiography
Hemangioma (1-10 cm)	++	+++	++++		+++
	Hyperechoic Doppler: low flow, low index, absence of spectral broadening	Peripheral puddles, fill in from periphery, enhancement on delayed scan	Peripheral enhancement centripetal progression Hyperintense on T2, hypo intense on T1 SS > 95%, SP 95%	No uptake	Cotton wool pooling of contrast, normal vessels without AV shunt, persistent enhancement
Focal fatty liver	+	++	+++		Normal finding
	Hyper echoic, no mass effect, no vessel displacement	Sharp interface Low density (< 40 u)		No uptake
FNH (< 3 cm)	+	++	++++		+++
	Homogenous iso, hypo, or hyper echoic, central hyper echoic area Central arterial signal Doppler: high flow, spectral broadening	Homogeneous enhance strongly with hepatic arterial phase Isodense with liver; Central low density scar	Hyper vascular +Gd Isodense T1 Hyper intense scar T2 SS > 95%; SP > 95%	No uptake	Hyper vascular 70% centrifugal supply
Adenoma (5-10 cm)	+	++	++		++
	Heterogeneous Hyper echoic If haemorrhage: anechoic center In doppler: variable flow, spectral broadening	Homogenous > Heterogeneous, Peripheral feeders filling in from periphery	Capsule, Hyper intense in T1 (intra lesional fat)	No uptake uptake if degenera-tion to HCC	Hyper vascular Large peripheral Vessel Central scar if haemorrhage
HCC	+	+++	+++	+	++++
	Hypo or hyper echoic Doppler: hyper vascular Doppler: index and flow high, spectral broadening	Hyper vascular, often irregular borders Heterogeneous > Homogeneous abnormal internal vessel Hallmark is venous washout SS 52%-54%	Hyper vascular Poor different: Hypo intense T-1, Hyper intense T2 Well different: Hyper intense T-1, Iso intense T-2 SS 53%-78%	Increased uptake, but many HCCs show no uptake at PET	Hyper vascular Av shunting Angiogenesis
Cholangio-carcinoma	Bile duct dilatation if major ducts are involved. Intra-hepatic CCC: no bile dilatation	Hypo dense lesion. Delayed enhancement	Hypo intense T1 Hyper intense T2 MRCP is useful	Uptake ++ SS 93%	Hypervascular
Metastasis	+1	+++	+++	+++++	++++
	SS 40%-70% hypo to hyper echoic; doppler; low index and flow; presence of spectral broadening	SS 49%-74 % complete ring enhancement	SS 68%-90 % Low intensity T-1 High intensity T-2	SS 90%-100%	SS 88%-95% hyper vascular

¹Intraoperative ultrasound, contrast ultrasound and EUS are highly sensitive to detect liver mass; +: Degree of accuracy; SS: Sensitivity; SP: Specificity; MRI: Magnetic resonance imaging; CT: Computed tomography; HCC: Hepatocellular carcinoma.

Table 3 Immunohistochemical staining in the evaluation of hepatic tumors

Tumor	Recommended immunostaining
HCC	Polyclonal CEA
	Cytokeratin 8/18 pair (+/+ staining)
	Cytokeratin 7/20 pair(-/- staining)
	Hep Par 1, AFP
Cholangiocarcinoma	Cytokeratin 7/19 pair (+/+ staining)
	Cytokeratin 7/20 pair (+/- staining)
	B-HCG, CEA, Mucin-1
Epithelioid hemangioendothelioma	CD34
	CD31
	Factor VIII
Angiomyolipoma	HMB-45, smooth muscle actin
Metastatic carcinoma
Neuroendocrine	Chromagin, synaptophysin, neural enolase
Pancreas	Cytokeratin 7/20 pair (+/+ staining)
Colorectal	Cytokeratin 7/20 pair( -/+ staining)
Breast	Cytokeratin 7/20 pair (+/- staining)
Lung	Cytokeratin 7/20 pair (+/- staining)