Vol. 7, Issue 3, Part D (2024)

Background: Renal cell carcinoma comprises 85% of adult kidney tumors, with its incidence rising due to improved abdominal imaging. Diagnosis relies on Hematoxylin-Eosin stained slides, immunohistochemistry, and molecular studies. Subtyping Renal cell carcinoma is crucial for prognosis, and Carbonic anhydrase IX (CAIX) expression aids in subclassification. This study evaluates CAIX expression frequency in RCC subtypes and its association with clinicopathological parameters, including age, gender, laterality, histopathological subtype, grade, and stage.

Methods: A retrospective and prospective case series study included 40 cases of primary renal cell carcinoma diagnosed between June 2021 and June 2023. Samples were collected from Al-Jumhori Teaching Hospital, AL-Rabee Private Hospital, and private laboratories in Nineveh province. The study was conducted from January 1, 2023, to September 1, 2023. Carbonic anhydrase IX protein expression was tested using immunohistochemistry with a rabbit monoclonal primary antibody (isotype IgG, clone EP161) supplied by Bio SB company, USA.

Results: The study included 40 renal cell carcinoma cases, with ages ranging from 21-77 years (mean 55.55±12.46). The sample comprised 70% males and 30% females, with 67.5% being clear cell subtype, 20% papillary, 10% chromophobe, and 2.5% clear cell-papillary variant. Significant CAIX expression was found in clear cell RCC, especially in lower-grade tumors, with no significant association with age, gender, laterality, or stage.

Conclusion: CAIX was mainly positive in clear cell subtype, thus it has important role in the differentiation of renal cell carcinoma subtypes and also for differentiating renal cell carcinoma from its mimickers. CAIX has significant association with grade of the tumor. No association was found between CAIX expression and age, gender, laterality & stage of the tumor.