CASE 3638 Published on 16.01.2007

Rapidly growing focal nodular hyperplasia in a 8 yr. old girl

Section

Abdominal imaging

Case Type

Clinical Cases

Authors

Vora P, Rawlinson J

Patient

8 years, female

Clinical History
An 8 year girl presented with abdominal pain. Imaging suggested a benign liver tumour. Over a two year period the lesion increased significantly in size. Repeat imaging together with biopsy demonstrated typical features of Focal Nodular Hyperplasia (FNH).
Imaging Findings
An 8 year old girl presented with non specific abdominal pain. No significant past medical history. Clinical examination was normal. Ultrasound (US) examination of the abdomen showed a 40 x 48 x 46 mm liver lesion (Fig 1). This was thought to be benign on the basis of the clinical findings, normal liver function tests and the imaging. Two years later she re-presented with abdominal pain localised to the right upper quadrant of the abdomen. No new clinical findings were apparent. A repeat US scan showed that the liver lesion had grown significantly, doubling its dimensions (97x 76x 87mm) (Fig 2). In view of its growth further characterization was performed with MRI. This showed typical findings of focal nodular hyperplasia that is: isointense lesion with a central scar which was low signal on T1W and high signal on T2W (Fig 3, 4). After gadolinium, the lesion enhanced in the arterial phase, becoming isointense in the venous phase while the scar exhibited delayed enhancement (Fig 5, 6). Although a confident diagnosis of FNH was made on the basis of the imaging, the increase in size caused sufficient clinical concern to justify a biopsy (Fig 7). Histological examination confirmed the diagnosis of FNH. The child is presently on a regular followup.
Discussion
FNH is the second most common benign liver tumour after cavernous haemangioma, comprising 8% of primary liver tumours. Females are affected more often than males and thay are commonly detected in the third to fifth decade(1). It is quoted as being very rare in children (2). One series mentions an annual incidence of approximately 0.02% in the general paediatric population(3). It is usually solitary but can be multicentric in up to 20% of cases. FNH is thought to represent a hyperplastic response of normal liver cells to a congenital vascular anomaly, producing a tumour with its sole blood supply from the hepatic artery. Typically less than 5 cm in diameter and well circumscribed these tumours are homogeneous and do not demonstrate haemorrhage, necrosis or calcification. Most of these lesions are detected as incidental findings and are asymptomatic. FNH has varied appearances on ultrasound, ranging from isoechoic with respect to the liver in 40%, when it may only be visible if the hepatic contour is abnormal, hypoechoic in 40% or hyperechoic in 20% of cases. Whatever is the pattern, FNH appears homogeneous 80% of the time. FNH is usually well defined with sharp margination due to the capsule which is present in almost all masses. Addtionally a centrally placed stellate scar may be present in upto 25% of the cases. Doppler sonograms demonstrate an enlarged afferent blood vessel with central arterial hypervascularity and centrifugal filling to the periphery in a spokelike manner. Large draining veins may be seen at the periphery of the mass. Echo-enhanced Doppler US yields a high sensitivity in the detection of the feeding artery and in the depiction of the radial vascular architecture in FNH, which is highly specific for the diagnosis. Sensitivity and specificity of MRI are respectively 70% and 98% for the diagnosis of FNH. It is isointense to hypointense on T1W and on T2W is slightly hyperintense to isointense. The central scar is hypointense on T1W and hyperintense on T2W. After the administration of gadolinium, the lesion demonstrates vivid and uniform enhancement in the arterial phase, but becomes isointense on the portal venous and delayed phases. However, the central scar, present in the majority of cases, does not enhance during the arterial phase but typically exhibits delayed enhancement(4,5,6). Although these typical imaging features were demonstrated, our case is unusual for two reasons: firstly, FNH are rare in children and secondly, they are typically stable lesions without significant growth. Incidence of FNH is about 2% of all pediatric hepatic tumours(7) and they are not commonly associated with rapid growth. In one series, reduction in size or complete resolution occurred in 50% of cases(8). The combination of these factors made us proceed with a histological diagnosis despite the typical diagnostic imaging features.
Differential Diagnosis List
Focal nodular hyperplasia
Final Diagnosis
Focal nodular hyperplasia
Case information
URL: https://eurorad.org/case/3638
DOI: 10.1594/EURORAD/CASE.3638
ISSN: 1563-4086