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Abdomen » Hepatobiliary
Telangiectatic Focal Nodular Hyperplasia
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Presentation 39-year-old female with increased serum alkaline phosphatase
 
 
 
Caption: Sagittal RUQ
Description: Liver and R kidney are demonstrated. There is a large solid mass in the inferior R lobe of the liver. The mass exhibits a hypoechoic "halo" where it is contiguous with the right lobe of the liver.
 
 
 
Caption: Sagittal image of the mass
Description: The mass exhibits a dense liver-like echo pattern with through-transmission roughly equivalent to that the the normal-appearing liver. There is some irregularity in the internal echo pattern within the mass.
 
 
 
Caption: Sagittal Color Doppler of the mass
Description: On color Doppler the mass exhibits sparse internal vascularity with no obvious organization to the vascular structures.
 
 
 
Caption: CT Abdomen
Description: Arterial phase
 
 
 
Caption: CT Abdomen
Description: Portal Venous Phase. Triphasic CT of the Liver Performed Without and With IV Contrast: Demonstrates a 12.5 x 10.0 x 13.5 cm heterogeneously enhancing mass arising from the inferior aspect of the right hepatic lobe. Based on the imaging findings alone, the differential diagnosis for this mass could also include a hepatic adenoma or hepatocellular carcinoma. The liver is otherwise normal in appearance.
 
 
 
Caption: MR Abdomen
Description: Coronal SS FSE
 
 
 
Caption: MR Abdomen
Description: 
 
 
 
Caption: MR Abdomen
Description: LAVA Post-Gadolinium – Arterial Phase
 
 
 
Caption: MR Abdomen
Description: LAVA Post-Gadolinium – Portal Venous Phase. MRI of the Abdomen Without and With Gadolinium Enhancement demonstrates a 12 x 9 x 13 cm (AP, trans, CC) well-defined, primarily exophytic mass arising from the inferior right lobe of the liver. This mass has mixed signal characteristics and irregular hyperenhancement. Although not the usual MRI findings of FNH, the mass is consistent with a biopsy-proven telangiectatic subtype of FNH. No additional liver lesions seen.
 
Differential Diagnosis
  1. Fibrolamellar HCC
  2. Hepatic Adenoma
  3. atypical FNH
 
Final Diagnosis Telangiectatic Focal Nodular Hyperplasia
 
Discussion Focal nodular hyperplasia (FNH) is the second most common benign hepatic tumor, with hemangioma being the most common.  FNH makes up approximately 8% of all primary hepatic tumors [1].  The pathogenesis of FNH is unclear, and the lesion may actually represent a nonneoplastic, hyperplastic response to a congenital vascular malformation [2].  FNH is seen in up to 3% of the population, with a female-to-male ratio of approximately 7 to 1.  Oral contraceptives may be associated with FNH, although the use of oral contraceptives is thought to accelerate the growth of existing lesion, rather than cause the formation of new lesions.  FNH lesions are rarely symptomatic [1].

The classic histologic pattern of a typical FNH is a central or peripheral fibrous stellate “scar” with radiating septa containing malformed vascular structures and cholangiolar proliferation [3].  Telangiectatic FNH is a histologic variant of FNH characterized by one-cell-thick hepatic plates separated by sinusoidal dilatation, with no central scar or architectural distortion [4].  In telangiectatic FNH, arteries have hypertrophied muscular media but no intimal proliferation in contrast to the classic form.  Also, these abnormal vessels drain directly into sinusoids, while in classic FNH, connections to the sinusoids are rarely seen [4].  It has been suggested that telangiectatic FNH may display a molecular pattern closer to that of hepatocellular adenoma [5].  

Since FNH is benign and complications are rare, the goal of imaging these patients is to firmly establish the diagnosis in order to suggest conservative therapy [6].  Telangiectatic FNH can, however, pose a challenge to imagers in that its imaging characteristics can differ significantly from classic FNH.  

The classic imaging finding of FNH have been well described.  On US, there is often only a subtle difference on echogenicity between FNH and normal liver.  FNH may be slightly hypoechoic, isoechoic, or slightly hyperechoic to normal hepatic parenchyma.  Doppler US may demonstrate the classic “spoke-wheel” pattern of vascularity [1].  On noncontrast CT, FNH is usually isoattenuating to normal liver and homogeneous.  In late arterial phase, there is bright homogeneous enhancement and often a hypodense central scar.  In portal venous phase, FNH is once again isoattenuating to normal liver, and can be difficult to detect.  Delayed phase can sometimes show hyperattenuation of the central scar and septa due to late opacification of the fibrous components [7].  On MRI, FNH is slightly hypointense or isointense on T1, and slightly hyperintense or isointense on T2.  The central scar is usually bright on T2.  With dynamic gadolinium enhancement, FNH shows similar enhancement patterns to CT [1].

Telangiectatic FNH, by contrast, frequently demonstrates atypical imaging features such as lesion heterogeneity, lack of a central scar, hyperintensity on T1WI, marked hyperintensity on T2WI, and persistent contrast enhancement on CT or MR imaging.  No specific US patterns for telangiectatic FNH have been identified, and the US appearance may be indeterminate [6].

 
Case References 1.    Choi BY and Nguyen MH.  The Diagnosis and Management of Benign Hepatic Tumors.  J Clin Gastroenterol 2005; 39:401-412.
2.    Columbo M.  Malignant neoplasms of the liver.  In:  Schiff ER, Sorrell MF, Maddrey WC eds. Schiff’s Diseases of the Liver, 9th ed.  2002:1377-1403.
3.    Ferlicot S, Kobeiter H, Van Nhieu J, et al.  MRI of atypical focal nodular hyperplasia: Radiologic-pathologic correlation.  AJR 2004;182:1227-1231.
4.    Nguyen BN, Flejou JF, Terris B, et al.  Focal nodular hyperplasia of the liver:  a comprehensive pathologic study of 305 lesions and recognition of new histologic forms.  Am J Surg Pathol 1999; 23:560-564.
5.    Paradis V, Benzekri A, Dargere D, et al.  Telangiectatic focal nodular hyperplasia: a variant of hepatocellular adenoma.  Gastroenterology 2004; 126(5): 1323-9.
6.    Attal P, Vilgrain V, Brancatelli G, et al.  Telangiectatic focal nodular hyperplasia: US, CT, and MR imaging findings with histopathologic correlation in 13 cases.  Radiology 2003; 228(2): 465-472.
7.    Carlson SK, Johnson CD, Bender CE, Welch TJ.  CT of focal nodular hyperplasia of the liver. AJR 2000; 174: 705-712.
 
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