This document describes the radiological features of follicular nodular hyperplasia (FNH) seen on ultrasound, CT, MRI, and other imaging modalities. Key points include: - On ultrasound, FNH lesions appear similar in reflectivity to the liver but can cause mass effect. A central scar is rarely seen. Doppler signals may be seen within and at the edge of lesions. - On CT, lesions appear well-defined with mass effect. Attenuation matches the liver. A central low attenuation scar is seen. Arterial phase shows uniform enhancement except for the scar. Portal and delayed phases show isoattenuation with the liver and slow scar enhancement. - MRI shows similar enhancement

1. FOLLICULAR NODULAR
HYPERPLASIA
• An underlying congenital vascular lesion composed of normal
liver elements (hepatocytes, bile ducts, Kupffer cells and
intervening fibrous septa) ▶ however, there is a lack of normal
liver architecture (e.g. there are absent portal tracts)
• It may enlarge in response to hormone stimulation (e.g. oral
contraceptives)
• It is the 2nd commonest benign hepatic tumour

2. CLINICAL PRESENTATION
•It is usually asymptomatic (it may present with pain or
hepatomegaly)
•It occurs most commonly in women aged 20–50 years (and is
multiple in 20% of cases)
FOLLICULAR NODULAR
HYPERPLASIA

3. RADIOLOGICALFEATURES
• A central stellate fibrovascular scar is seen in 50% of cases
• there is no true capsule
• calcification, necrosis and haemorrhage are extremely rare (even large
lesions do not usually outgrow their blood supply)
ULTRASOUND
• There are non-specific features with lesions demonstrating a similar
reflectivity to the adjacent liver (but demonstrating mass effect)
• the central scar is rarely seen
• Doppler signals can be seen within and at the edge of the lesion

4. US appearance of FNH. (a) Sagittal US scan shows FNH that is slightly
hypoechoic relative to the surrounding liver tissue (arrows) and causes
slight distortion of the outer liver contour.

5. Figure 5b. Sagittal oblique US scan of another patient
shows FNH that is well differentiated from the
surrounding liver tissue (arrow). There is a suggestion
of radiating septa within the lesion.

6. Figure 5c. Axial US scan of another patient shows
FNH that is profoundly hypoechoic (arrow) due to
diffuse fatty infiltration of the surrounding liver tissue.

7. RADIOLOGICALFEATURES
NECT
• A well-defined mass which often exhibits a mass effect (with vessel
displacement)
• the lesion demonstrates the same attenuation as the surrounding liver
• there is a central low attenuation scar
CECT
• Arterial phase:
• uniform enhancement (except for the scar)
• there can be large peripheral feeding vessels
• Portal phase:
• the attenuation is identical to normal liver (the scar remains low
attenuation)
• Delayed imaging:
• there is slow scar enhancement

8. Figure 6a. CT appearance of typical FNH with pathologic
correlation. (a) Precontrast CT image shows a large lesion
(straight arrow) that is only slightly hypoattenuating relative to
the surrounding liver tissue. Within the lesion, a central scar
(curved arrow) can be seen.

9. Figure 6b. Contrast-enhanced CT image obtained during the arterial
phase shows intense homogeneous enhancement of the lesion
(straight arrow), except for the central scar (curved arrow).

10. Figure 6c. Contrast-enhanced CT image obtained during the
portal phase shows that the lesion (straight arrow) has
become isoattenuating relative to the liver. The central scar
(curved arrow) has not yet fully enhanced.

11. MRI
•The same enhancement pattern is seen as for CT ▶ the specificity increases
with iron oxide agents (which are taken up by the Kupffer cells).
•T1WI:
• intermediate or minimal low SI
• a low SI central scar
•T2WI:
• intermediate to high SI
• a high SI central scar
•T1WI + Gad:
• marked, homogeneous arterial phase enhancement that becomes
isointense during the portal venous phase
• there can also be a peripheral, ring-type delayed enhancement pattern
on delayed images obtained 1 h after hepatocyte selective gadolinium
chelate administration
• The central scar usually demonstrates delayed enhancement
•DWI:
• generally isointense

12. Figure 7a. MR imaging appearance of typical FNH. (a) Axial T2-
weighted single-shot fast spin-echo (SE) image shows a large FNH
lesion (straight arrow) that is isointense relative to the surrounding
liver parenchyma. The central scar (curved arrow) has slightly higher
signal intensity than the lesion.

13. Figure 7b. Axial gadolinium-enhanced 2D T1-weighted GRE image
obtained during the arterial phase shows intense homogeneous
enhancement of the entire lesion (straight arrow), except for the central
scar (curved arrow)

14. Figure 7c. Axial gadolinium-enhanced 2D T1-weighted GRE image
obtained during the portal phase shows that the lesion (straight
arrow) has become isointense relative to the surrounding liver
parenchyma, and the central scar (curved arrow) has enhanced.

15. RADIOLOGICALFEATURES
• Sulphur colloid
• This is usually normal (due to Kupffer cell activity within the
lesion)
• DSA
• A vascular mass with a large tortuous central sup- plying artery ▶
radiating vessels spread out to supply the lesion

16. CASE 2
• A 31 years old female working as a staff nurse at Institut
Kanser Negara - treated as PTB.
• Sputum MTB Cn& S- shows non-tuberculous mycobacterium .
• Developed transaminitis while on antiTB.
• US noted multiple liver lesion ? abscess or TB lesion. Lesion
persistent despite near completion of anti-TB.
• Hepatitis screening: non reactive

17. US HBS 08/08/2018
• Liver parenchyma shows increased in echogenicity with
smooth liver margin.
• There are hypoechoic lesions seen in:
• segment V/VI  1.5 x 2.1 x 2.0 cm
• Segment VII  1.9 x 1.2 x 1.4 cm and 1.2 x 2.2cm
• Impression: 1) Multiple hypoechoic liver lesions in segment V/VI
and VII could be abscesses or Tuberculosis lesions. 2) Fatty liver

19. US HBS 20/02/2019
• The previous hypoechoeic lesions in segment V (measuring 2.5 x 2.3
cm) and IVb ( measuring 1.8 x1.4 cm ) are relatively unchanged in
size but are hyperechoeic in this current US.
Another smaller hypoechoic lesion at segment VI is unchanged in
echogenicity and size. It measures 2.2 x 1.8 cm
• Impressions:
Multiple right liver lesions with no significant change in size.
• The segment V and IVb lesions have changed in echogenicity from
hypo to hyperechoeic
• segment VI lesion remains hypoechoeic.
• DDx solidified abscess, organized hematoma, hemangioma.

21. CT HBS 08/04/2019
• Liver is mildly enlarged (span 21cm), margins are smooth and
regular.
• There are few well-circumscribed lesions of varying sizes i.e. at
segments VI/VII and VIII.
• These lesions shows hypoattenuation on pre-contrasted
images, progressive enhancement through the contrasted
phases showing globular and centripetal pattern and
homogenisation in the delayed phases. The largest measuring
2.0cm x 2.5cm at segment VII.