[369] Utility of Carbonic Anhydrase-IX in the Diagnosis of Metastatic Conventional Renal Cell Carcinoma by Fine-Needle Aspiration Biopsy

Xiaoling Guo, Berrin Ustun, Adebowale Adeniran, David Chhieng, Angelique Levi. Yale University School of Medicine, New Haven, CT

Background: Expression of the commercially available antibody against Carbonic anhydrase-IX (CAIX) has been shown to be useful in the diagnosis of metastatic conventional renal cell carcinoma (cRCC) in surgical pathology specimens, but studies demonstrating its utility in cases of metastatic cRCC from cell-block sections of aspiration biopsies are limited. The objective of the current study was to compare CAIX expression with other immunohistochemical markers routinely used in the diagnosis of metastatic cRCC (CD10, and Vimentin) in cell block material from fine-needle aspiration biopsies (FNABs), and to asses its utility in confirming the diagnosis of metastatic cRCC in cytologic specimens.
Design: Thirteen metastatic RCC specimens from 12 patients were immunostained with CAIX, CD10, and Vimentin. The immunoreactivity results were compared. The metastatic sites included pancreas (4), thoracic lymph nodes (4), bone (3), soft tissue (1), and pleural fluid (1). The patient ages ranged from 57 to 86 years old, (mean age of 67). The commercially available CAIX antibody, clone NB100-417 (Novus Biological, Littleton, CO), was used in this study. Immunohistochemistry (IHC) staining was performed and immunoreactivity was graded as 0, no tumor cells immunoreactive (IR); 1+, 1% to 25% IR; 2+, 25% to 50% IR; and 3+, greater than 50% IR.
Results: Eleven of 13 (85%) cases showed 3+ strong and diffuse membranous staining with CAIX; 12 of 13 (92%) cases showed similar 3+ IR with CD10; and 9 of 12 (75%) cases showed 3+ strong and diffuse cytoplasmic IR for Vimentin. In 1 case where CAIX IR was 1+, both CD10 and Vimentin showed 3+ IR; while in the other case where CAIX IR was 1+, CD10 showed 0 IR and Vimentin showed 1+ IR. Morphologically, 12 of 13 metastatic cRCCs showed small to intermediate sized nuclei with relatively inconspicuous nucleoli, and 1 case showed larger nuclei with prominent nucleoli. In the 2 cases where CAIX showed 1+ IR, the tumor cells were intermediate in size with inconspicuous nucleoli. In the 1 case with prominent nucleoli, both CAIX and CD10 showed 3+ IR, while Vimentin showed 1+ IR.
Conclusions: The majority of cases in this study showed strong and diffuse expression of CAIX, and with the exception of 1 case the expression of CD10 and Vimentin was comparable. This study suggests that CAIX is a useful marker in addition to CD10 and Vimentin to confirm the diagnosis of metastatic cRCC in cytologic cell block material from various anatomical sites.
Category: Cytopathology

Wednesday, March 21, 2012 1:00 PM

Poster Session VI # 93, Wednesday Afternoon


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