Resident Program - Case of the Month

November 2023 – Presented by Dr. Alex Chau (Mentored by Dr. Maaya Wilton)

Discussion

The histology of the liver shows a clear cell variant of hepatocellular carcinoma. This variant is present in up to 40% of cases of hepatocellular carcinoma but is the dominant morphology in only 5 – 16% of cases. To diagnose the clear cell variant of hepatocellular carcinoma greater than 80% of the cells must demonstrate a clear cytoplasm. This clear cytoplasm is caused by glycogen accumulation within the cells. For this case, the clinicians were worried that the liver mass was a metastasis from the previous lung biopsy, but histologically the cells were different. The stains that were used to diagnose this case were TTF-1 to rule out lung origin and arginase and HepPar1 to rule in liver origin. The other answers such as chromogranin, synaptophysin, MOC31 were for a neuroendocrine tumor, S100, HMB45, MelanA, HepPar1 would be for a melanoma, and PAX8 and RCC would be for renal cell carcinoma. The clear cell variant of hepatocellular carcinoma stains positively HepPar1 in 82-97% of cases and is negative for EMA and LeuM1 which would be positive in renal cell carcinoma. Additionally further testing could be done using ISH for albumin which is positive in 93% of cases.

References

1. Jain D. "HCC - clear cell variant". PathologyOutlines.com website. Accessed January 8th, 2024.
2. Histopathological Variants of Hepatocellular Carcinomas: an Update According to the 5th Edition of the WHO Classification of Digestive System Tumors. J Liver Cancer. 2020;20(1):17-24. Published online March 31, 2020. DOI: https://doi.org/10.17998/jlc.20.1.17