Afectaciones sociales

See text fo r description.

1 Vascular invasion

Or Capsular invasion

Or

ITiree o f the following:

□ Necrosis present □ Cellular atypia = 3-5 □ Trabecular thickness >4 □ Mitosis present □ Reticulin loss = 4-5 □ Capillarization =5 HCC YES NO

Boxes above and below are ticked, as appropriate. Features present in box 1 ( i f less than three in total) are added up to box 3 (H C C > D N > M R N ).

2

a Necrosis not present

□ Vascular invasion not present

a Capsular invasion not present

□ Mitosis not present

HCC > DN > M RN DN > HCC > MRN M RN > DN > HCC □ Capillarization = 4 □ Solitary arterioles >1 □ Heterogeneity present □ Reticulin loss = 1-3 □ T rabecular thickness = 4 □ Capillarization = 3 □ Cellular atypia = 1-2 □ Trabecular thickness <4 □ Solitary arterioles <1 □ Capillarization = 0-2 □ Cellular atypia = 0 □ Heterogeneity = 0 □ Reticulin loss = 0

The values shown in chart 3.4 and table 3.5 can be distributed into five main groups, depending on their proportional representation in the three categories HCC, DN and MRN. These five groups of values are organized in the 5 boxes of chart 3.5 as follows:

- Box 1= Values present, on average, in 36% of HCC but not present In MRN or DN; - Box 2= Values present, on average, in all MRN and DN, and, on average in 67% of HCC; - Box 3= Values present, on average, in 47% HCC, 37% DN and 20%MRN;

- Box 4= Values present, on average, in 31% DN, 26% HCC and 12% MRN; - Box 5= Values present, on average, in 91% MRN, 63% DN and 11% HCC.

For example, a hypothetical lesion is assessed using the scoring system. The values (i.e. original observations) or denomination (i.e. present/absent) of each component of the scoring system is allocated to each box.

Box 1 contains those values that in my series of 212 nodules were identified, on average, in 36% of HCC, in none (except 1) of DN, and in none of the MRN. If vascular or capsular invasion were considered as evidence of malignancy, than the presence of either would define a lesion as HCC. Three of the remaining values of box 1 would be suggestive of HCC.

If these criteria are not fulfilled, then the number of values in box 1 together with any value of box 3 is balanced against the number of values in boxes 2, 4, and 5, which represent those values observed (in my series of 212 nodules) more frequently in either MRN or DN. If the balance is in favour of either MRN or DN (i.e. more values in boxes 2, 4, and 5), the number of values in box 4 and 5 could be used to decide whether the lesion is more likely to be DN or MRN (any value of box 1 or 3 could be used in favour of DN, and added to any value of box 4). An even balance would favour DN.

This algorithm is hypothetical, and represents just a possible application of the scoring system. The idea of including all variables in the evaluation tree has the advantage that the final assignment does not rest on a single feature (or sum of features), but on the balance of all components. For example, the high scores of the MRN of table 3.6 (see previous paragraph) were due to (regardless of size) capillarization, and a combination of heterogeneity, and capillarization respectively. The algorithm would classify these lesions as MRN, on balance.

3.4.3 Further considerations

The scoring system has to be tested for inter and intra-observer variability (Scheuer 1996). If an acceptable level of agreement is found then the scoring system may facilitate the comparison of clinical, pathological and molecular studies without the complication of adapting and translating one nomenclature into the other. Despite the consensus document published by the International Working Party (Anonymous et al. 1995), the terminology used in the literature is still confusing, particularly due to the use of different classifications and different histological criteria by different centres (Kojiro 2000). In fact, the bulk of the relevant literature offers few clues about which precise observations allocated any particular lesion (however named) into the given categorical assignment. Assessment of individual features may provide more accurate data compared to "overall diagnosis", to define objectively what is meant by "atypia" of liver nodules (Terasaki et al. 1998). It is my intention to test the intra and interobserver variability of this histological scoring system, and this will be the subject of further work.

How the scoring system could be applied to routine histological work is unclear, as yet. The scoring system was designed for the assessment of nodules identified in livers removed at transplantation for the purpose of correlation with quantitative molecular analysis and clinical follow-up. I have

not tested, the prognostic value of the scoring system, and it is my intention to do so when sufficient follow up data is available. Even though the prognosis of cirrhotic patients with HCC depends not only on tumour-related factors, but also on the severity of any underlying liver dysfunction and patient performance status (Ebara et al. 1986; Johnson et al. 2000), it would be interesting to see if patients with overt HCC with a relatively low score have a different outcome compared to "high scoring" overt HCC. If the scoring system has prognostic value, it could be used as part of the histological evaluation of overt HCC identified in livers removed at transplantation.

The prognostic value of the histological scoring system could also be tested on HCC arisen in non-cirrhotic livers and removed by surgical resection. Presumably in these patients performance status and severity of liver dysfunction have a lesser impact (compared to cirrhotic patients) on the outcome and therefore the histological assessment could give a major contribution to the prognosis.

The EASL panel on HCC (Bruix et al. 2001) has recommended the use of biopsy for the assessment of nodules 1-2 cm diameter, during the surveillance of cirrhotic patients. A minority of small HCC may be high grade, and the diagnosis will not be difficult (except that a small high grade tumour raises the possibility that it is a metastasis). However most HCC of this size will be well differentiated and difficult to recognize. My personal view is that the histological criteria for the diagnostic assessment of liver nodules in cirrhosis are inadequate, in most cases for this exacting task, especially with this size range of nodules, the confusion about nomenclature and given our present state of knowledge (Quaglia et al. 2001). In particular the histological assessment of biopsy samples is hindered by sampling error (Huang et al. 1996). I do not think that the use of the scoring system would solve this inadequacy. At the moment, I do not envisage the application of the scoring system for the histological assessment of biopsy samples during the clinical

surveillance of cirrhotic patients. However, work such as that described here may help to define important features when the whole lesion is available for study, and these features (histological and molecular) may be applicable to smaller needle biopsies in the future.

In summary, the histological score I have described should give more precise indication of the position of a hepatocellular lesion in the benign to malignant evolutionary spectrum. In order to validate this scoring system, further work was performed to compare scores with molecular and clinical follow-up data.

This molecular analysis consisted of the assessment of clonality and genomic heterogeneity. Monoclonality is said to identify neoplastic cell populations but does not indicate malignancy. Malignancy is associated with tumour progression, with increasing tumour grade and tumour heterogeneity as malignant neoplasms acquire the capability of invasion and metastasis. The identification of genomic heterogeneity within a neoplastic population (defined for present purposes by monoclonality) implies that spontaneous genomic mutations have occurred which may eventually lead to frank malignancy. The assessment of the degree of genomic damage within a heterogeneous neoplastic population may indicate how advanced this progression is, and may be used for correlation with phenotypic (i.e. histological) and clinical variables (Arribas et al. 1997).

In chapters 5, 8, and 9 I describe my work on clonality, genomic heterogeneity and the establishment of the molecular techniques involved. The correlation between the histological assessment, the molecular analysis and the clinical data is discussed in chapter 10.

In the next chapter the pathogenesis and histological features of a number of lesions reminiscent of FNH in cirrhotic liver, identified as the "high scoring" DN described above, are discussed.

CHAPTER 4

Focal nodular hyperplasia-like areas