4. Molecular analysis

are considered the strongest parameters discriminating HCC from high-grade dysplastic

If high-grade malignant tumour is found in the liver, the differential diagnosis includes metastatic malignancy versus HCC and cholangiocarcinoma. Any malignant tumour can ultimately spread to the liver via bloodstream, lymphogeneous dissemination or transperitoneal spread. In some biopsy series, metastatic lung, colorectal, pancreatic and breast carcinomas have been the most common secondary liver tumours [3]. However, frequency of different metastatic malignant tumours in liver biopsies depends on many factors, including the biological potential of the tumour and its incidence in the population as well as institutional approach to liver biopsy in different oncological patients. This, in turn, may depend on the patient's general status, presence of contraindications for biopsy or significant oncological treatment and the

In order to distinguish HCC from metastatic tumours, it is advisable to combine at least two hepatocellular markers and at least two antigens that are more frequently seen in adenocarcinomas. Among hepatocellular markers, Arg1 should be combined with either HepPar1 or GPC3. Most of adenocarcinomas express cytokeratin (CK) 19, MOC-31 and CK7 [55]. The spectrum of immunohistochemical panel should be planned in accordance with tissue availability within the biopsy. The suggested minimal panel includes ARG1 and CK19 [55], while maximal investigation might include several HCC markers accounting for different grades of HCC, several adenocarcinoma markers and antigens that are characteristic for certain tissues (neuroendocrine or melanocytic differentiation) or epithelia of specific organs, e.g., breast, large bowel, lung, thyroid, kidney and others. Panels of immunohistochemical markers can disclose the location of primary tumour giving rise to metastasis. Thus, CK20 and CXD2 are typical for metastatic colorectal carcinoma; CDX2 and CK7 for gastric carcinoma; TTF-1 and napsin A for lung adenocarcinoma and oestrogen receptor, mammaglobin, GATA3 or GCDFP-15 for breast cancer [65]. The expression frequencies of different tissue- and organ-specific antigens in metastases and corresponding primary tumours are further outlined in Table 4.

Antigen Tumour Frequency, % References CDX2 Colorectal carcinoma 100 [66] CDX2 Metastatic colorectal carcinoma 96.7–100 [67, 68] SATB2 Primary colorectal carcinoma 96.0 [68] SATB2 Metastatic colorectal carcinoma 92.2 [68] CK20 Metastatic colorectal carcinoma 97.1 [68] TTF-1 Lung adenocarcinoma 83.3 [69] Napsin A Lung adenocarcinoma 86.7 [69] HMB-45 Metastatic melanoma 76–81 [70, 71] MART-1 Melanoma 48.4–83 [72, 73]

nodule [3].

3.5. Hepatocellular carcinoma versus metastasis

34 Hepatocellular Carcinoma - Advances in Diagnosis and Treatment

availability of effective treatment.

The molecular classification of hepatocellular carcinoma is still developing. Thus, different approaches have been proposed. Although the present tools of molecular analysis assure the

technical background for in-depth studies, HCC might be more difficult target for the systematisation of molecular findings than other tumours. The problems are associated with heterogeneity of etiological factors and their geographic distribution in different populations

Diagnostic Algorithm of Hepatocellular Carcinoma: Classics and Innovations in Radiology and Pathology

http://dx.doi.org/10.5772/intechopen.76136

37

A trans-ancestry study has been carried out involving 608 cases of HCC. The cohort was created to reflect both etiological and geographic/genetic diversity of HCC. The main identified molecular targets were TP53–Rb pathway, Wnt pathway, modulators of chromatin and transcription,

French research team has recently proposed molecular classification into six subtypes, designated as G1–G6. The first three subtypes are characterised by TP53 mutations and are highgrade tumours. G1–G2 share AXIN1 and ATM mutations, while G1 also possesses RPS6KA3 mutations. G3 is characterised by mutations in TSC1/TSC2 and FGF19. G3 is also associated with haemochromatosis, macrovascular invasion, macrotrabecular and compact histological pattern as well as presence of multinucleated and pleomorphic cells. Sarcomatoid changes are more frequent in G1–G2, but clear cells—in G1. G4–G6 lack TP53 mutations and are low-grade tumours. G5–G6 exhibit mutations in CTNNB1 gene, while G4 lacks both mutations in TP53 and CTNNB1. G4 tumours are more frequently characterised by small size, steatohepatitic morphology and inflammatory infiltrates as well as absence of satellite nodules and vascular invasion. G5–G6 carcinomas display microtrabecular pattern, cholestasis and lack inflammatory infiltrates. By immunohistochemistry, these HCCs are characterised by nuclear expression

Nowadays, the classic diagnostic algorithm of HCC (see Figure 1) includes the evaluation of risk factors in a given patient to assess the need for surveillance. Cirrhotic patients are referred to ultrasound examination once per 6 months. Suspicious nodules are further evaluated by CT and MRI. Characteristic findings by CT and MRI including arterial hypervascularisation represent the basis of non-invasive diagnostics. In controversial and non-cirrhotic cases, biopsy is indicated that might need supplementation by immunohistochemistry according to the morphological features. Innovations are expected in the field of miRNA-based liquid biopsy to support radiological diagnosis, addition of SIR assessment and miRNA profile to select the optimal treatment, e.g. possibly broadening Milan criteria (see also chapter "Innovative Blood Tests for Hepatocellular Carcinoma: Liquid Biopsy and Evaluation of Systemic Inflammatory Reaction"), and novel immunohistochemical markers for cases that still remain ambiguous.

HCC is a frequent and aggressive malignant tumour, estimated to range sixth by incidence and second by mortality in the global cancer statistics. The high ratio of mortality to incidence (0.95)

mTOR–PIK3CA pathway and mutations in genes regulating telomere maintenance [82].

of beta catenin and strong positivity for glutamine synthetase [52].

5. Diagnostic algorithm of hepatocellular carcinoma

with diverse genetic background [81].

6. Conclusions

Figure 1. Diagnostic algorithm of hepatocellular carcinoma. 1—Recommended by the American Association for the Study of the Liver diseases (AASLD). 2—Recommended by the European Association for the Study of the Liver (EASL). Abbreviations: RFs, risk factors; vs, versus; HBV, hepatitis B virus; HCC, hepatocellular carcinoma; HCV, hepatitis C virus; US, ultrasonography; CT, computed tomography; MRI, magnetic resonance imaging; HGDN, high-grade dysplastic nodule; FNH, focal nodular hyperplasia; IHC, immunohistochemistry; SIR, systemic inflammatory response; mi, micro; RNA; ribonucleic acid.

technical background for in-depth studies, HCC might be more difficult target for the systematisation of molecular findings than other tumours. The problems are associated with heterogeneity of etiological factors and their geographic distribution in different populations with diverse genetic background [81].

A trans-ancestry study has been carried out involving 608 cases of HCC. The cohort was created to reflect both etiological and geographic/genetic diversity of HCC. The main identified molecular targets were TP53–Rb pathway, Wnt pathway, modulators of chromatin and transcription, mTOR–PIK3CA pathway and mutations in genes regulating telomere maintenance [82].

French research team has recently proposed molecular classification into six subtypes, designated as G1–G6. The first three subtypes are characterised by TP53 mutations and are highgrade tumours. G1–G2 share AXIN1 and ATM mutations, while G1 also possesses RPS6KA3 mutations. G3 is characterised by mutations in TSC1/TSC2 and FGF19. G3 is also associated with haemochromatosis, macrovascular invasion, macrotrabecular and compact histological pattern as well as presence of multinucleated and pleomorphic cells. Sarcomatoid changes are more frequent in G1–G2, but clear cells—in G1. G4–G6 lack TP53 mutations and are low-grade tumours. G5–G6 exhibit mutations in CTNNB1 gene, while G4 lacks both mutations in TP53 and CTNNB1. G4 tumours are more frequently characterised by small size, steatohepatitic morphology and inflammatory infiltrates as well as absence of satellite nodules and vascular invasion. G5–G6 carcinomas display microtrabecular pattern, cholestasis and lack inflammatory infiltrates. By immunohistochemistry, these HCCs are characterised by nuclear expression of beta catenin and strong positivity for glutamine synthetase [52].
