[767] Pitfalls in Using High Molecular Weight Cytokeratin 34BE12 (CK903) and P63/Racemase Staining To Evaulate Cauterized Glands at the Margin in Radical Prostatectomy.

Dengfeng Cao, Peter Humphrey. Washington University School of Medicine, St. Louis

Background: Patients with a positive margin in radical prostatectomy (RP) have an increased risk of biochemical recurrence. Therefore it is critical to accurately assess the margin status in RP. However, sometimes the glands at the margin (ATM) in RP are cauterized making it difficult to determine their nature (benign versus malignant). The goal of this study to evaluate the utility of high molecular weight cytokeratin 34BE12 (CK903) and p63/racemase in distinguishing cauterized benign glands (CBGs) from cauterized malignant glands (CMGs) ATM in RP.
Design: Sixty RPs specimens with cauterized glands ATM were included: 32 with CBGs, 19 with CMGs, 9 with both CBGs and CMGs. One to two paraffin blocks containing CBGs and/or CMGs were used for staining with 34BE12 and p63/racemase. Both CBGs and MBGs ATM were evaluated for 34BE12 and p63/racemase staining, and their staining intensity was also compared to that in their non-cauterized counterparts [non-cauterized bengin glands (NCBGs), non-cauterized maignant glands (NCMGs)] in the immediate adajcent area.
Results: CBGs ATM showed negative 34BE12 and p63 staining in 3/41 and 5/41 cases, respectively. In additon, some but not all CBGs ATM showed loss of 34BE12 and p63 staining in 2/41 and 7/41 cases, respectively. The CBGs ATM showed weak racemase staining in 2/41 cases. When compared to adjacent NCBGs, CBGs ATM showed decreased staining intensity for 34BE12 and p63 in 25/38 (66%) and 31/36 (86%) cases, respectively. CMGs ATM showed negative 34BE12 and p63 staining in 28/28 cases. Positive racemase staining was seen in CMGs ATM in 22/28 cases (weak in 13, strong in 9). In cases with weak or no racemase staining in CMGs at the margin, the racemase staining intensity typically decreases from the adjacent NCMGs (strong intensity in 28/28) to CMGs not at the margin to CMGs ATM. 34BE12 and p63 demonstrated 93% (38/41) and 88% (36/41) sensitivity to distinguish CBGs from MBGs ATM, respectively (specificity 90% (28/31) and 85% (28/33), respectively). Racemase demonstrated 22/28 (79%) sensitivity and 22/24 (92%) specifivity for identifying CMGs ATM (strong racemase staining is 100% specific for CMGs ATM).
Conclusions: The immunoreactivity of 34BE12 and p63 was lost in CBGs ATM in a small percentage of cases. Negative racemase staining was seen in CMGs ATM in a higher percentage of cases. One should be cautious in using 34BE12 and p63/racemase staining to distinguish CBGs from CMGs at the margin. Immunohistochemical evaluation should be always used along with morphologic patterns.
Category: Genitourinary (including renal tumors)

Monday, February 28, 2011 1:00 PM

Poster Session II # 124, Monday Afternoon


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