[1041] Gata3 Expression in Paragangliomas: A Pitfall That Could Lead to Misdiagnosis of Urothelial Carcinoma

Jeffrey S So, Jonathan I Epstein. Johns Hopkins Medical Institutions, Baltimore, MD

Background: GATA3 is a zinc finger transcription factor, which is expressed in various normal and neoplastic tissues. Amongst tumors, it labels urothelial carcinoma, collecting duct carcinoma of the kidney, breast carcinoma, lymphoma, and uncommonly endometrial carcinoma. Few studies have investigated its positivity in various neoplasms that may mimic urothelial neoplasms. It is increasingly being used as a relatively specific marker for urothelial carcinoma, especially in the differential diagnosis with adenocarcinoma of the prostate where GATA3 is negative. In this study, we evaluated GATA3 expression in urinary bladder paragangliomas, which may closely mimic urothelial carcinomas, as paragangliomas can have a diffuse growth pattern, bizarre nuclei, mitoses, deep muscle or vascular invasion, or focal hemorrhage and necrosis. Diagnostic difficulties can also be encountered in significantly cauterized and small biopsy specimens.
Design: We retrieved 12 cases of paragangliomas involving the urinary bladder and 20 cases of paragangliomas from non-urologic sites using the Hopkins Pathology Data Base (PDS) system. Whole slides were stained for the bladder tumors and paragangliomas from other sites were constructed into tissue microarrays, wherein 3 cores from each tumor were taken.
Results: GATA3 was positive in 10 of the 12 (83.3%) urinary bladder paragangliomas. Most (6/10) of the staining was diffusely strong (3+) staining, while the rest (4/10) which were positive showed mixed intensities (strong 3+ to moderate 2+). 15/20 (75%) paragangliomas outside of the bladder were positive for GATA3 staining. Moderate (2+) or Strong (3+) staining was seen in 13/20 (65%) of extra-vesical paragangliomas, ranging from 5%-100% of the cells labeling (mean 58.5%, median 60%). In the remaining 7/20 (35%) cases, only weak (2/7) or negative (5/7) immunoreactivity for GATA3 was seen. Overall for paragangliomas regardless of site, 79.2% were positive for GATA3.
Conclusions: Recognition of GATA3 positivity in paragangliomas will aid pathologists in preventing a misdiagnosis of a urothelial tumor based on GATA3 expression, which is critical given the differences in treatment, follow-up, and prognosis between bladder paragangliomas and urothelial carcinoma. When presented with a metastasis from an unknown primary, knowledge of GATA3 immunoreactivity in paragangliomas can also prevent a misdiagnosis of metastatic urothelial carcinoma.
Category: Genitourinary (including renal tumors)

Monday, March 4, 2013 1:00 PM

Poster Session II # 179, Monday Afternoon


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