Contribution of Cell Block Preparation to the Diagnosis of Hepatocellular Carcinoma- A Rural Perspective

Background: World-wide hepatocellular carcinoma (HCC) is the sixth most common cancer and fourth leading cause of cancer related deaths. Metastases are about 18- 40 times commoner than HCC and have some morphological similarities with it, but their prognosis and treatment approaches vary. Fine needle aspiration cytology (FNAC) alone faces some diagnostic challenge to differentiate between poorly differentiated HCC and metastatic carcinoma. Cell block preparation utilizing material obtained through ultrasound (USG) guided FNAC of liver tumors is easy and is a safer procedure than more invasive core needle biopsy. Glypican-3 (GPC-3), a member of heparan sulfate proteoglycan family, when used on histopathology sections, has an important diagnostic role in differentiating HCC from other hepatic mimickers. The present study aimed at assessing the diagnostic utility of Glypican-3 IHC stain on cell block preparation for differentiating primary from secondary hepatic malignancies. No such study has thus far been conducted from our sub-himalayan region. Materials and Methods: The present study was an institution based observational study with cross sectional design conducted in a tertiary care centre of Eastern India among patients referred to Department of Pathology for USG guided FNAC of hepatic mass and suspected to have HCC or metastases clinically and / or radiologically. Under USG guidance, FNAC was performed twice followed by core needle biopsy from the hepatic mass. Cell blocks were prepared from the second pass aspirate by plasma-thrombin clot method. The cell block and core needle biopsy specimens were stained by hematoxylin and eosin (H&E) and subjected to immunohistochemistry (IHC) using Glypican-3 IHC by labelled Horse Radish Peroxidase (HRP) polymer technique. The diagnostic utility of Glypican-3 IHC staining was analyzed with the help of core needle biopsy results as a gold standard. Results: The study population comprised of 60 cases of hepatic SOL, among which on core needle biopsy, 24 were diagnosed as HCC and 36 as metastatic carcinoma in liver. The sensitivity, specificity and diagnostic accuracy of FNAC was found to be 87.5%, 83.4% and 85% respectively. The same for cell block preparation came out to be 91.7%, 88.9% and 90% respectively. When Glypican-3 IHC stain was done on cell block preparation, the sensitivity, specificity and diagnostic accuracy increased to 95.8%, 94.5% and 95% respectively. Conclusion: The present study revealed that in cases of HCC, diagnostic accuracy of cell block is greater than FNAC in differentiating it from hepatic secondaries. IHC staining for Glypican-3 in cell block preparation is an even more sensitive and specific and is a valuable tool capable of differentiating HCC from metastatic carcinoma of liver.