Immunohistochemical expression of microvascular density and carbonic anhydrase IX in renal carcinoma. Relation to histological type and tumoral progression

Abstract

Purpose

To correlate the immunohistochemical expression of microvascular density (MVD) and carbonic anhydrase IX (CAIX) with the different histological subtypes of renal cell carcinoma and its progression.

Material and methods

We studied 93 patients with renal cell carcinoma operated between 1990 and 2008. Antibodies employed for immunohistochemistry (IHC); CD31 (1: 40, Dako) and CD 34 (1: 50, Dako) for MVD and CAIX (1: 100, Santa Cruz). CAIX was validated semi-quantitatively as: strongly positive (> 85%); weakly positive (10%–85%); and negative (< 10%), independently of the intensity of the stain. MVD was validated with both anti-CD31 and anti-CD34 by means of a whole section to select the microscopic field (x100) with highest density of stained vessels, counting the number of vessels in a photographic field of 0.53 mm². Results are expressed as the maximal number of vessels by mm² of tumour tissue.

Results

The median follow-up was 40 months (1–160). We found no differences of expression with any of the 3 IHC markers between tumours that progressed (49) and tumours that did not progress (44). The IHC expression of CAIX was strongly related to MVD, measured for both CD31 and CD34 (p< 0.0001). MVD with both antibodies was inversely related to tumour size and the Fuhrman grade and was also stronger in clear cell carcinomas compared to the rest of histological subtypes, measured by CD31 (p = 0.001) and CD34 (p = 0.003).

Conclusions

Neither MVD nor CAIX expressions were related to tumour progression, but were related to histological subtypes. This fact, added to their co-expression, could prompt the use of the CAIX expression, which is far more reproducible as a quick and easy approximation to MVD. More research should be done to use it as a marker for targeted therapy.

Resumen

Objetivos

Relacionar la expresión inmunohistoquímica (IHQ) de la densidad microvascular (DMV) y de la anhidrasa carbónica IX (ACIX) con los tipos histológicos de carcinoma renal (CR) y con su progresión.

Material y métodos

Se estudiaron 93 pacientes operados por CR entre 1990–2008. Anticuerpos: CD31 (1: 40, Dako) y CD 34 (1: 50, Dako) para DMV y ACIX (1: 100, Santa Cruz). ACIX se valoró semicuantitativamente; intensamente positivos (> 85%), débilmente positivos (10%–85%) y negativos (< 10%), independientemente de la intensidad de la tinción. La DMV se valoró independientemente con anti-CD31 y anti-CD34. Campo de bajo aumento (x100) con mayor densidad de vasos teñidos; se contabilizó el número de vasos en un campo fotográfico de 0,53 mm². Resultados expresados como número máximo de vasos/mm² de tejido tumoral.

Resultados

Mediana seguimiento; 40 meses (1–160). No encontramos diferencias IHQ para ninguno de los 3 marcadores entre tumores que progresan (49) y no progresan (44). La expresión de ACIX estaba relacionada con la DMV (p < 0,0001). La DMV se relacionó inversamente con el tamaño tumoral y con el grado de Fuhrman de forma significativa. Así mismo, fue significativamente mayor en los CR de células claras tanto medida con CD31 (p = 0,001) como con CD34 (p = 0,003) frente al resto de subtipos histológicos. Conclusiones: La DMV y la expresión de ACIX no se relacionan con la progresión, pero sí con el tipo tumoral. Ello y su coexpresividad permitiría usar la expresión de ACIX como medida orientativa rápida y fácil para medir DMV y su posible relación con la respuesta a antiangiogénicos.