[790] Expression of Novel Markers Human Kidney Injury Molecule-1 (Hkim-1), S100A1 and Napsin A in the Differential Diagnosis of Renal Cell Carcinomas (RCC) with Clear and Papillary Features

Manju Aron, Mitual Amin, Ping Zhang, Mariza DePeralta-Venturina, Sambit K Mohanty, Sijian Wang, Mahul B Amin. Cedars-Sinai Medical Center, Los Angeles, CA; William Beaumont Hospital, Detroit

Background: The differential diagnosis of RCC with clear and papillary features includes the well established subtypes such as clear cell RCC, papillary (pap) RCC and recently recognized rarer subtypes including clear cell-papillary RCC (CC-PRCC) and translocation associated RCC. Expression of newer markers of RCC including hKIM-1, Napsin A, and S100A1 have not been reported in CC-PRCC and translocation associated RCC. hKIM-1 is a type I transmembrane glycoprotein expressed in injured renal proximal tubules but not in the normal nephron. S100A1 is a calcium-binding protein of the EF-hand family which is expressed in the entire nephron except the glomerulus. Napsin A is an aspartic proteinase that is expressed in type II pneumocytes, and the proximal and distal convoluted tubules of the kidney. This study was conducted to evaluate the utility of these markers in the differential diagnosis of RCC with clear and papillary features.
Design: 33 RCCs [translocation associated RCC (n=7), CC-PRCC (n=12), clear cell RCC (n=7) and pap RCC (n=7)] were included in the study. Representative sections were studied to confirm the histological diagnosis and sections from the tumor were stained with hKIM-1, S100A1 and Napsin A. The Kim-1 staining was graded as: 0=absent, 1+=<10%, 2+=11%- 50%, 3+=>50%. Napsin A and S100A1 stains were semiquantitatively graded as: 0 =absent; 1=weak, <25%; 2= moderate, 25-50%; 3=strong,> 50%.
Results: The results of the study are outlined in the table with immunoreactivity reported as percent positive.

DiagnosishKIM-1S100A1Napsin A
Translocation RCC868671
Clear cell RCC10010086∗
Pap RCC8610086
∗ weak staining seen in a majority of cases

Of note only 9% of CC-PRCC stained with hKIM-1 while all the clear cell RCC and 86% of the pap RCC and translocation RCC stained with this antibody. In addition, cases of clear cell RCC and CC-PRCC showed weak and focal staining with Napsin A.
Conclusions: 1) hKIM-1 has potential diagnostic utility in the distinction of CC-PRCC from clear cell RCC and pap RCC. 2) S100A1 is expressed in the entire range of analyzed RCCs with clear and papillary features. 3) Napsin A has distinct but limited expression in the subtypes of RCCs. Awareness of this data is critical while evaluating metastatic tumors in which pulmonary adenocarcinomas and RCC are in the differential diagnosis.
Category: Genitourinary (including renal tumors)

Tuesday, March 20, 2012 9:30 AM

Poster Session III # 152, Tuesday Morning


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