Ano de publicação: 2010
AUTORIA:
Roula Albadine, MD*, Luciana Schultz, MD*, Peter Illei, MD*, Dilek Ertoy, MD†, Jessica
Hicks, MS*, Rajni Sharma, PhD*, Jonathan I. Epstein*,‡,§, and George J. Netto, MD*,‡,§
*Department of Pathology, Johns Hopkins University, Baltimore, MD
‡Department of Urology, Johns Hopkins University, Baltimore, MD
§Department of Oncology, Johns Hopkins University, Baltimore, MD
†Department of Oncology, Hacettepe University, Ankara, Turkey
RESUMO:
Background—Collecting duct carcinoma (CDC) is a relatively rare but aggressive type of renal
malignancy with variable morphologic features. One of the World Health Organization diagnostic
criteria for CDC is the exclusion of urothelial carcinoma of renal pelvis from the differential
diagnosis. PAX8 is a novel lineage restricted transcription factor expressed in renal tubules. We
investigated the expression pattern of PAX8 in CDC and its utility, in combination with p63, in
resolving the differential diagnosis of CDC versus upper tract urothelial carcinoma (UUC).
Design—Archival tissues from 21 CDC and 34 UUC were retrieved from our institutional files.
Immunohistochemistry for PAX8 and p63 were performed on routine and tissue microarray
sections using standard immunohistochemistry protocol. Intensity of nuclear staining was
evaluated for each marker and assigned an incremental 0, 1+, 2+, and 3+ score. Extent of staining
was categorized as focal (<25%), nonfocal (25% to 75%), or diffuse (>75%).
Results—CDC: All 21 (100%) CDC were positive for PAX8. Intensity of expression was
moderate to strong (2+/3+) in 19 cases (90%). Extent of staining was diffuse in 13 of 21 tumors.
The p63 was positive in 3 of 21 (14%) CDC cases (PAX8+/p63+). UUC: The 34 UUC included 5
pT1, 4 pT2, and 25 pT3/pT4 tumors. Thirty-one of 34 (91.2%) UUC were negative for PAX8,
whereas 33 of 34 (97%) were p63 positive. Staining intensity was moderate in 15 cases (44%), of
which 12 were nonfocal or diffuse. The unique p63-negative UUC was a pT1 tumor that was also
negative for PAX8 (PAX8−/p63−).
Conclusions—We propose the use of the combination of PAX8 and p63 in the diagnosis of
poorly differentiated renal sinus epithelial neoplasms where the differential diagnosis includes
CDC versus UUC. The immunoprofile of PAX8+/p63− supports the diagnosis of CDC with a
sensitivity of 85.7% and a specificity of 100%. In contrast, a (PAX8−/p63+) profile supports the
diagnosis of UUC with a sensitivity of 88.2% and a specificity of 100%. The inverse PAX8/p63
expression seen in CDC and UUC supports a renal tubular rather than an urothelial differentiation
in CDC given the nephric lineage restriction of PAX8.