6 November 2009 – Case of the Week #161
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Case of the Week #161
An 18 year old man presented with abdominal pain. CT scans showed a large abdominal mass. A core biopsy was obtained.
H&E, low power
H&E, high power Pale bodies, high power
CK7 CK20 HepPar
Ki67 pCEA Vimentin
What is your diagnosis?
Hepatocellular carcinoma, fibrolamellar variant
Fibrolamellar hepatocellular carcinoma is uncommon, and usually affects young adults aged 20-40 years (eMedicine). It accounts for fewer than 10% of all cases of HCC, but 35% of all cases in patients younger than 50 years.
Fibrolamellar carcinoma is typically not associated with underlying liver disease, jaundice or elevated serum levels of alpha-fetoprotein. The tumors are typically large at diagnosis (mean 10-20 cm), with regional lymph node metastases in 50-70%.
Microscopically, fibrolamellar carcinomas have nests, sheets or cords of malignant cells, which are separated by lamellar bands of dense, hypocellular collagen connective tissue. The fibrotic connective tissue coalesces into the central scar. The malignant cells are usually large, well-differentiated polygonal cells containing granular cytoplasm, large nuclei, and prominent nucleoli (Adv Anat Pathol 2007;14:217). Vascular invasion and necrosis are common, and mitotic figures may be present. Fibrolamellar carcinoma is typically immunoreactive for HepPar and CK7 (Am J Clin Pathol 2005;124:512).
The differential diagnosis includes:
• Focal nodular hyperplasia: usually 5 cm or less, fibrous stroma contains bile ductules and inflammatory cells, no hepatocyte atypia
• Hepatocellular carcinoma, sclerosing variant: pseudoglandular pattern common, no oncocytes, smaller tumor cells
• Adenosquamous carcinoma with sclerosis
• Metastatic carcinoma with sclerotic stroma
• Paraganglioma: may have nesting pattern at biopsy, round nuclei without atypia, vascular stroma but typically no dense fibrosis, positive for neuroendocrine markers (Am J Surg Pathol 2002;26:945)
Fibrolamellar hepatocellular carcinoma is treated with aggressive surgery (Am J Gastroenterol 2009;104:2617). The 5 year survival is 60-75%, better than classic hepatocellular carcinoma (Cancer 2006;106:1331). Early detection of relapse combined with multimodality therapy has been recommended (Eur J Surg Oncol 2009;35:617). These tumors overall show fewer chromosomal abnormalities than classic HCC, and tumors with no cytogenetic changes appear to behave less aggressively (Mod Pathol 2009;22:134)
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