To the Editor.--In their recent article, Ozcan et al (1) describe PAX-2 as a useful marker for diagnosing metastatic renal cell carcinoma (RCC).
We wish to point out a very important limitation of PAX-2 that is not highlighted in the published article.
We recently per formed PAX-2 in a lymph node to exclude metastatic RCC.
Given that PAX-2 staining is seen in lymphocytes, it is very important to recognize this limitation when evaluating lymph nodes for metastatic lesions, especially in the workup of unknown primary tumors.
PAX-2 is a helpful marker for diagnosing metastatic renal cell carcinoma: comparison with the renal cell carcinoma marker antigen and kidney-specific cadherin.
C-terminal activating and inhibitory domains determine the transactivation potential of BSAP (Pax-5), Pax-2 and Pax-8.
Several immunohistochemical markers are known to help in the diagnosis of renal neoplasms, among which are the renal cell carcinoma marker antigen (RCCM), kidney-specific cadherin (KSC), and PAX-2. (4-12)
PAX-2 is a member of the paired box family of transcription factors, which is required for development and proliferation of the kidney, brain, and mullerian organs.
In this study, we evaluate the diagnostic sensitivity and specificity of PAX-2 in metastatic tumors from both RCC and other tumor types, and we compare the expression of PAX-2 in metastatic RCCs with that of RCCM or KSC.
Since previous studies show that a percentage of mullerian-type tumors (ovary, fallopian tube, and endometrium) also express PAX-2, preference was given to their corresponding metastasis.
To compare the expression of PAX-2, RCCM, and KSC in metastatic RCCs, consecutive tissue sections from each metastatic RCC were submitted for immunostaining with these 3 markers.
The expression of PAX-2, RCCM, and KSC was correlated with histologic types of metastatic RCC.