Case of the Week

Background:

• Fibrolamellar hepatocellular carcinoma (FLC) is a rare histologic variant of hepatocellular carcinoma that appears most commonly in teenagers and young adults, without underlying liver disease.  FLC is most frequently diagnosed at an advanced stage. Brain metastases from solid tumors are exceedingly rare in the pediatric and young adult population, with only a handful of cases reported in the literature. The lesions tend to be large at diagnosis and imaged because of an acute clinical deterioration. This suggests that intracranial lesions may be asymptomatic for lengthy periods of time, making diagnosis difficult and leading some authors to recommend surveillance neuroimaging.

Clinical Presentation:

• Patients frequently present with abdominal pain, malaise and weight loss, a palpable abdominal mass, or hepatomegaly.
• Rarely, FLC may present with recurrent deep vein thrombosis, fulminant liver failure, encephalopathy, or Budd-Chiari syndrome.

Key Diagnostic Features:

• To date, there are few reported cases of brain metastases from fibrolamellar carcinoma. Many are visualized on MRI as a solid mass with midline shift, heterogeneous signal intensity on T1 and T2-weighted sequences, with regions of marked hypointensity on T2 gradient sequences. Contrast-enhanced T1-weighted images show increased enhancement of the lesion. Lesions may be surrounded by vasogenic edema.

Differential Diagnoses:

• Renal, pulmonary, breast, and melanoma metastases: these are more commonly intra-axial lesions located at the gray-white interface, commonly with associated vasogenic edema. On CT without contrast, they appear as hypo- or isodense lesions and on MR imaging as hypointense lesions on T1-weighted images with perilesional T2 hyperintensity relating to edema. Melanoma or hemorrhagic metastases can be hyperintense on T1-weighted images. Breast cancer metastases may be extra-axial, however, they usually present much earlier and as smaller lesions. Most metastases enhance avidly following contrast administration on both CT and MRI. The contrast pattern can be homogeneous, heterogeneous, or annular.

Treatment:

• Wide surgical resection of early lesions is the only potentially curative treatment, but it is possible only in a minority of patients due to the indolent growth.