[906] Immunohistochemical Expression of SALL4 in Hepatocellular Carcinoma, a Potential Pitfall in the Differential Diagnosis of Yolk Sac Tumors

Betina Katz, Nilda D Gonzalez-Roibon, Alcides Chaux, Rajni Sharma, George J Netto, Michael Torbenson. The Johns Hopkins University SOM, Baltimore, MD

Background: SALL4 is a transcription factor that has been used as a marker for testicular germ cell tumors, including yolk salk tumor (YST). YST displays several histological patterns, including a hepatoid pattern that can resemble hepatocellular carcinoma (HCC). Given that both neoplasms share the expression of markers such as alpha-feto protein and glypican 3, SALL4 could prove to be of utility in resolving such a differential diagnosis. Previous studies have suggested that HCC is negative for SALL4. The current study evaluates SALL4 expression in a large series of HCC.
Design: Seventy-two formaline-fixed paraffin-embedded samples of HCC were retrieved from our surgical pathology archives and used to construct a set of nine tissue microarrays. Paired tumor and nonneoplastic liver parenchyma samples were spotted in 4-8 cores each. SALL4 expression was evaluated using standard immunohistochemistry (Sigma, SALL4 clone 6e3). Percentage and patterns of nuclear expression were assessed in each spot. Mean percent expression was calculated for each tumor. A cut off of 5% or more was used to indicate a positive SALL4 result.
Results: SALL4 expression was not identified in any of the nonneoplastic liver samples (0%). In contrast, 17/72 HCC (24%) were positive for SALL4. The pattern of nuclear expression in HCC was diffuse in 2 positive cases and punctuate/clumped in the remaing 15. Overall, positive cases of HCC showed strong (2+ or 3+) SALL4 expression.
Conclusions: This is the first report of positive expression of SALL4 in HCC (24%). This finding should be taken into consideration in the differential diagnosis of HCC vs YST. The unusual punctuate/clumped pattern seen in our HCC cases has not been previously described in YST and appears to be the most frequent pattern of nuclear expression in HCC. The significance of the latter pattern of staining requires further study.
Category: Genitourinary (including renal tumors)

Monday, March 19, 2012 1:00 PM

Poster Session II # 143, Monday Afternoon

 

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