Focal Nodular
Hyperplasia (FNH)
Epidemiology:
- Female
preponderance
- Young
to middle-aged adults
- OCP
may cause growth (but not thought to be causative)
- Leading
hypothesis:
- A hyperplastic and altered growth response to changes
in blood flow in the parenchyma surrounding a preexisting arterial
malformation
Common sites:
Gross features:
- solitary or multiple (20%)
- may
be associated with a hepatic hemangioma
- often subcapsular
- well-demarcated
- poorly-encapsulated
- gray-white
- paler
than surrounding liver
- central
gray-white, depressed scar with fibrovascular septae radiating to the periphery (most)
Histologic
features:
- nodular
architecture
- fibrous
bands partially separating the nodules
- no
normal portal tracts within the lesion usually
- central
fibrous zone
- thick-walled,
medium to large vessels, usually arteries, in the scar with fibromuscular hyperplasia
- eccentric
or concentric narrowing of lumen
- not
accompanied by similar size duct or portal vein
- unaccompanied
arteries not found within hepatocyte
parenchyma
- exuberant
bile duct proliferation along radiating septal
margins and at edge of nodules(important)
- foci
of intense lymphocytic infiltrates maybe
- parenchyma
between septa have a thickened plate architecture characteristic of
regeneration
- normal
appearing hepatocytes
- focal
atypical hepatocytes maybe
Immunophenotype:
|
Marker:
|
Sensitivity:
|
Specificity:
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CAM 5.2
|
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|
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pCEA
|
|
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CD34
(endothelial cells lining the plates)
|
Often
|
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AFP (neg)
|
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Molecular features:
Other features:
References:
- Odze RD, ed. (2004) Surgical
Pathology of the GI Tract, Liver, Biliary
Tract, and Pancreas.