This document discusses various types of liver lesions including regenerative nodules, dysplastic nodules, hepatocellular adenoma, focal nodular hyperplasia, and hepatocellular carcinoma. It provides details on the histological and immunohistochemical features that can help differentiate these lesions. Key points include that dysplastic nodules are believed to be HCC precursors, hepatocellular adenomas can be single or multifocal and classified based on molecular features, and the distinction between well-differentiated HCC and hepatocellular adenoma can be challenging based on overlapping histological features alone.

1. Dr.Niharika SiNgh
gaNDhi MeDical
college
Bhopal

3. There is observation of hepatic progenitor cell features in
hepatocellular neoplasms at an early stage (dysplastic
nodules) or advanced tumours with mixed hepatocellular and

4. The 4th edition of the WHO classification of tumours of the
digestive system

6. Regenerative hepatocellular
nodules
Boundaries consist usually of fibrous
septa, collapsed reticulin strands,
multilobular areas of parenchymal
collapse, atrophic hepatic plates, other
nodules or a combination of the above.

7. Acetaminophen Toxicity

8. 29 days
Serial biopsies from native liver during its
overy phase
following auxiliary transplantation
Acute necrosis with sparing of periportal hepatocytes results in
initial phase of hepatocellular proliferation, acute
inflammation and reticulin collapse with parenchymal

9. Acute liver failure due to acetaminophen overdose
146 days

10. 350 days
Resolution of inflammation, matrix reabsorption and
hepatic plates remodelling and growth lead eventually to
full reconstitution of the liver mass, involution of the graft

11. Regenerative nodule in nodular regenerative hyperplasia.
The nodular area is flanked by atrophic plates with
condensation of reticulin fibres but no bridging fibrosis.

12. Regenerative nodule in advanced stage
chronic hepatitis C. The nodular area is
In chronic hepatitis C, the
nodules are of small size due
to porto-portal and
porto-central bridging with
loss of the vascular anatomical
relationships .
Two cell- thick hepatic plates
are often present, and there
may be deposition of granules
of copper-binding protein at
the interface with the fibrous
septa which is an indirect sign
of advanced fibrosis may be
helpful in the interpretation of
core needle biopsy specimens,
in which nodule formation is
not readily apparent due to the
small size of the sample or the
large size of the nodules or
both.

13. Primary biliary cirrhosis.Bridging fibrosis linking up portal
tracts generate a ‘jigsaw puzzle’ pattern rather than round nodules.

14. Primary sclerosing cholangitis. Marked segmental hypertrophy
and lateral atrophy lead to severe distortion of the lobar anatomy.

15. Benign hyperplastic regenerative proces secondary to a local
abnormality of blood flow due to a vascular malformation
such as:
 Budd–Chiari syndrome,
 hereditary haemorrhagic telangiectasia,
 portal vein thrombosis/ atresia,
 congenital portosystemic shunt.
 Polyclonality, increased ANGPT1/ANGPT2 ratio.
 Usually solitary, but multiple vascular malformations
and coexist with intracranial tumour.
 Develops in noncirrhotic livers of women 30–40 years
FNH is usually the easiest to differentiate, due to its
architecture and bland appearance of lesional hepatocytes.

16. Macroscopically, FNH can range in size from a few mm to several cm.
It usually shows a pale, micronodular and firm parenchymal surface,
with or without a central scar.There is usually no capsule, the periphery
of the lesion merging with the adjacent liver .

17.  Microscopically, it consists of nodules of benign-looking
hepatocytes separated by fibrous septa containing a ductular
reaction, a lymphoid infiltrate and aberrant vascular
structures.

18. A 32-year-old woman transplanted for glycogen storage
disease type 1. A 10-mm hepatocellular adenoma showed
diffuse staining for glutamine synthetase.
No nuclear or cytoplasmic staining for -catenin wasβ
identified.
Please note background liver on the right hand side showing
normal glutamine synthetase expression by perivenular
hepatocytes.
52-year-old woman. Liver resection
for focal nodular hyperplasia.
The pattern of glutamine
synthetase is typically ‘map like’.

19.  An important practical point is the
identification of a regenerative nodule
in a core needle biopsy specimen, as
the changes can be very subtle and
easily overlooked.
 Signs representing that the needle has
hit a regenerative area:
1)Two-cell-thick hepatic plates in biopsy cores from adult
patients.
2)Thin hepatic plates sometimes in a parallel configuration.
3)Sinusoidal dilatation without other accompanying features
of venous outflow blockage.
4)Few focal deposits of copper binding protein on the orcein/
Victoria blue stain without other signs of biliary pathology.
*A full clinical history, close correlation with imaging findings
and ideally an adequate sample of lesional tissue along with
a separate sample of non-lesional tissue to assess the status
of background liver should be the basis for the histological
interpretation of liver nodules.

20. DYSPLASTIC NODULES
 Nodules of relatively small size, up to about
10–15 mm,identified in cirrhotic livers, an
showing atypical histological features without
fulfilling the criteria of HCC.
 These nodules are thought to be HCC precursors, based
mainly on the following observations:
 Their occurrence in livers affected elsewhere by overt HCC.
 The identification of small nodular lesions with atypical
features and containing foci of overt HCC
(nodule-in-nodule pattern).
 Similarities at molecular level with HCC.
 Clinicopathological studies based on biopsy and clinical
follow-up suggesting their transformation into HCC.
 Change in their vascular supply.
 Histologically,associated with the presence of
unpaired arteries and sinusoidal capillarisation marked by

21. Additional stains, which can be of help in identifying the
porto-lobular relationship, are immunohistochemistry for
 cytokeratins (e.g. Ker 7)
 glutamine synthetase
*To highlight portal regions and centrilobular venules,
respectively.
Degree of sinusoidal
capillarisation by
CD34
immunostaining.

22.  Arterialisation is exploited radiologically by demonstrating
contrast uptake in arterial phase and rapid washout in the
venous phase to the point that demonstration of
arterialisation by one or two imaging modalities is
considered to be sufficient for the diagnosis of HCC without
the need of histological confirmation.
 The use of liver biopsy is therefore confined to lesions with
atypical features on imaging.
 According to a recent consensus paper, dysplastic nodules
are further subdivided into
 Low-grade lesions: may be indistinguishable from large
regenerative nodules, differing only by the focal presence of
some of the dysplastic changes.
 High-grade lesions:nodules may be indistinguishable from
early HCC probably because they represent part of a
continuum.

23. Macroscopically, dysplastic
nodules are distinct from the
background liver in terms of
their size, appearance, colour,
texture and/or bulging cut surface.
Dysplastic nodule in cirrhotic liver
showing a nodule- in nodule pattern.
The line of triangles marks the
boundary of the nodule against the
background liver. The arrow indicates
an area of increased cell density.

24. • Changes in Nodule in Nodule pattern include
1)Siderosis
2)Copper/copper-binding protein deposits
3) Steatosis
4)Clear cell change
5)Mallory–Denk bodies
6)Increased trabecular thickness
7)Pseudoglandular structures
8)Nuclear hyperchromasia or irregularity
of the nuclear contour,
9)Cytoplasmic basophilia
10) Increased proliferative rate within areas of a nodule
or compared with background liver and loss of the
reticulin stroma.

25. 11)Large cell change, originally called liver cell dysplasia :
 Present in association with chronic liver disease
 Hepatocytes show large atypical nuclei with preserved nuclear
cytoplasmic ratio.
 Risk of development of HCC, particularly in patients with viral hepatitis,
 Associated with cholestasis and senescence
 More than one pathogenesis .
12)Small cell change
 Areas of increased cell density due to a reduction in hepatocyte size
Increased nuclear– cytoplasmic ratio
 Associated with nuclear hyperchromasia
 Irregularity of the nuclear contour.
 True precursor of HCC.
 A relationship between small cell change and progenitor cells has been
proposed on the basis of a similar immunohistochemical profile.
 Small cell change and large cell change are part of a constellation of
histological changes which may indicate an increased risk of HCC.
 The general view is that these changes should at least be mentioned in
a histology report as they may indicate an increased risk of HCC.

26.  Recent molecular studies have led to the introduction of
an immunohistochemical panels including:
 Heat-shock protein 70,
 Glypican 3
 Glutamine synthetase
 Deemed to be useful in differentiating dysplastic
nodules from overt HCC.
• Clathrin heavy chain and annexin-A2 have been shown
to improve the performance of this panel.
 Gene expression profiling has recently produced a
prognostic gene expression signature to predict the
development of HCC.
Lack of staining with all markers high-grade dysplastic nodule
Staining for one marker well-differentiated HCC but does not
exclude a high-grade dysplastic nodule
Staining for two or three markers well-differentiated HCC

27. Rather than separating categorically dysplastic nodules from HCC, the currently
accepted view is that HCC development and the transition between dysplasia and
HCC can be defined by three phases :

28. Hepatocellular adenoma
 Benign neoplasm of hepatocytes
 Risk factors-
 Exposure to oestrogens .
 Exposure to androgens.
 Glycogen storage disorders.
 Familial adenomatous polyposis.
 Can be single or multifocal,
in which case the term ‘adenomatosis’ may apply.
HCAs vary in size and are usually fairly well
circumscribed, with a soft cut surface often similar to
background liver, although in many cases areas of
haemorrhage, necrosis or fibrosis may be present.Immunohistochemistry for serum amyloid A or C-reactive
protein is usually helpful, as they are both strongly
expressed in inflammatory adenoma, ,in contrast to FNH

29. Hepatocellular adenoma subclassification
Category Histological
features
Clinical features
β-catenin
mutated
Pseudacinus
formation, atypia
Malignant transformation,
bleeding. usually in men.
HNF1 mutated Steatosis,
FABP deficient
Bleeding
Inflammatory
adenoma
(formerly
telangiectatic
FNH)
IL6ST gene
mutations
Intralesional
lymphocytosis,
ductules
(ck7+ve) and
sinusoidal dilation
(telangiectasia)
SAA and
CRP positive
Bleeding,
a percentage bears
β-catenin mutation.
Systemic
syndrome.
Associated with alcohol,
metabolic syndrome
Unclassified Nonspecific features Variable

30. Hepatocellular carcinoma
 More common in males.
 Risk factors:
 Hepatitis B and C virus infection
 Alcohol
 Aflatoxin
 Patients taking anabolic steroids
 Children with inherited
metabolic conditions such as
 tyrosinaemia,
 hypercytrullinaemia,
 biliary atresia,
 Byler’s disease,
 BSEPdeficiency and
 a-1-ATdeficiency.
Term ‘satellite’ is commonly used to describe
the presence of small tumoural nodules in the
vicinity of the main mass.

31.  Microscopically:
 Resemble to normal hepatocytes.
 Can be very heterogeneous
 Characterised by areas with
different growth patterns and
degree of differentiation.
Tumour cells are often arranged in
trabecular,pseudoacinar or
solid pattern.
 Well-differentiated HCC
Resembles normal hepatocytes with a similar nuclear–cytoplasmic ratio,
similar nucleolated nuclei, well-demarcated cell borders
eosinophilic cytoplasm.The cytoplasm may show steatosis or
clarification, and sometimes accumulation of Mallory–Denk bodies, or
eosinophilic globular inclusions.
 Formation of canalicular bile plugs is a diagnostic feature of HCC,
although nonlesional cholestatic hepatocellular rosettes may become
entrapped within the tumour and mistaken for a tumour component.
• HCC can grow inside large bile ducts

32.  HCC can grow into three main patterns
-Nodular,infiltrative pattern and diffuse pattern.
1) The nodular pattern is the one usually observed in cirrhotic
liver and consists of an expanding mass well demarcated from
the surrounding tissue often by interposition of a capsule a
with a multilobulated cut surface.
2) The infiltrative pattern is usually observed in noncirrhotic
livers and consists of a large mass which occupies a good
proportion of a lobe or more than one lobe.
The term ‘massive’ also applies to tumours of this size. There is
often involvement of large portal vein branches.
3) HCC in a diffuse pattern is rare, usually observed in cirrhotic
Livers and consists of multiple nodules which may mimic the
cirrhotic nodules, may not be visible on imaging and difficult to
identify macroscopically. The term ‘cirrhotomimetic’ is often
used to describe this pattern.

33.  Regression of fibrosis does not eliminate the risk of HCC.
HCC can occur in chronic viral hepatitis at a precirrhotic
stage.
 Cirrhosis is the main risk factor for HCC, but HCC can
arise in noncirrhotic livers. This may occur in the context of
the metabolic syndrome, or other factors (iron overload, past
exposure to HBV, androgens), and occasionally without any
signs of liver disease.
 HCC tends to be larger in noncirrhotic patients than in cirrhotic
ones, partly due to surveillance programmes in patients with
chronic liver disease, leading to its identification at a relatively
early stage.
 Of note cholangiocarcinoma has been described in non-biliary
cirrhosis.
 In non-cirrhotic liver the differential diagnosis is usually with
other primary epithelial or non-epithelial tumours(focal nodular
hyperplasia, hepatocellular adenoma, cholangiocarcinoma,
angiomyolipoma) or with metastases.

34.  Some patients, however,may not have any risk factor or sign of
liver injury .
 The fibrolamellar variant of HCC is
a well-recognised entity,
which affects young adults, without
underlying history of liver disease.
 Characterised by
 Fibrous stroma
 Large Hepatoid tumour cells
 Eosinophilic cytoplasm
 Cytoplasmic inclusions
 Scanty mitotic activity.
 A recent series has shown that fibrolamellar carcinoma does
not have a better survival than conventional HCC in children.
 Peculiar radiological and histological characteristics, spread and
behaviour, and its pathogenesis remains obscure.

35.  The histological appearance of HCA and well-
differentiated HCC can overlap considerably.
Of note, well differentiated HCC can appear very
bland, and HCA secondary to hormonal stimulation can
show marked atypia, but regresses following hormonal
withdrawal.
 There are no individual diagnostic histological features or
immunohistochemical markers that can be used reliably
and in isolation to distinguish between HCA and well-
differentiated HCC.
 The diagnosis of HCC in cirrhosis is now clinical in most
cases; the role of histology in the diagnosis of dysplastic
nodule and early HCC depends on local clinical practice.
 The inflammatory/telangiectatic variant may need to be
differentiated from FNH. The distinction between HCA and
HCC may be challenging.

36.  Other variants include
 Lymphocyte-rich
 Clear cell, scirrhous
 Sclerosing HCC.
 The term mixed or combined hepatocholangiocellular
carcinoma refers to tumours with mixed
hepatocholangiocellular phenotype, or
tumours with progenitor cell features.
 Lack of bile, no demonstrable canaliculus formation or
Hep-Par 1 expression by IHC, in the presence of mu
production, cytoplasmic staining for CEA, CA19-9 and
biliary cytokeratins favour cholangiocarcinoma.
 The presence of adenocarcinoma with a typical tubulo-
glandular pattern, in a core needle biopsy from a lesion
clinically suspected as HCC, raises the possibility of a
mixed (combined) hepatocellular-cholangiocarcinoma.It can
occur in non-biliary cirrhosis, and simulate clinically HCC.

37.  Staining for CEA using a polyclonal antibody or CD10 is the
most commonly used method to demonstrate canaliculus
formation, but its expression is not hepatocellular specific.
 Two recent studies have shown excellent specificity of
BSEP expression in distinguishing between HCC and its
extrahepatic mimics.
 Glypican-3 may complement Hep-Par-1 in the diagnosis of
poorly differentiated HCC , but it is expressed in non-
neoplastic liver parenchyma and extrahepatic tumours , and
should not be used in isolation.
 Expression of stem cell markers,biliary cytokeratins and a
gene expression profile similar to hepatoblast identifies a
subtype of HCC with poor prognosis .

38.  Angiomyolipoma
 Mimic histologically hepatocellular carcinoma.
 Diagnosis : HMB 45 Positive.
 Many extrahepatic primary tumours infiltrating the liver can simulate
hepatocellular carcinoma.Histologically and in particular
 Adrenal cortical carcinoma
 Neuroendocrine tumours
 Renal cell carcinoma
 Melanoma
 Hepatoid adenocarcinoma (e.g. gastric origin).
 Clinical evidence of an extrahepatic primary and
immunohistochemistry are often sufficient for the diagnosis, but in
some cases, the extrahepatic primary is too small to be detected
clinically (e.g. neuroendocrine tumours), or the tumour is poorly
differentiated and does not fit with any specific immunohistochemical
profile.
 Poorly differentatiated tumours of intestinal origin, and germ cell
tumours may be associated with high serum levels of alpha-
fetoprotein.

39. Future directions
 Recent studies using high-throughput molecular
techniques have classifiied HCC into subcategories
associated with specific aetiologies and specific
molecular pathways.
 The application of genomic profiling to the investigation
of HCC associated with rare conditions such as BSEP
deficiency may lead to the identification of alternative
carcinogenic pathways .
 Proteomics profiling of liver tumours appears promising
in identifying biomarkers, which can be exploited at
diagnostic histological level or clinically for noninvasive
diagnosis or to direct treatment .