title: PAX2 expression in Wilms tumors and other childhood neoplasms.
abstract: PAX2 plays an important role in kidney development; although small studies have demonstrated PAX2 expression in Wilms tumors (WT), comprehensive studies on formalin-fixed tissue are lacking. Thus, we systematically evaluated PAX2 immunohistochemical staining in a retrospective study of pediatric WT, as compared with other pediatric tumors. We stained formalin-fixed, paraffin-embedded sections from 39 WT, 6 nephrogenic rests, 8 non-Wilms renal tumors, and 43 nonrenal pediatric small round cell tumors with 2 different PAX2 polyclonal antibodies. PAX2 demonstrated strong, diffuse staining of epithelial and blastema components of WT (97% of cases). PAX2 stained WT stroma in fewer cases (23%), but 80% of anaplastic foci were positive. Nephrogenic rests, 1 case of metanephric adenoma, and 1 pediatric renal cell carcinoma were also PAX2 positive; other pediatric renal tumors were negative. Neuroblastoma, primitive neuroectodermal tumor/Ewings, and T-cell acute lymphoblastic lymphoma (ALL) were PAX2 negative. However, PAX2 weakly stained some cases of B-cell ALL rhabdomyosarcoma (RMS) was also stained, especially alveolar RMS (83%), with less staining of embryonal RMS (13%). One of the antibodies also stained maturing myoid cytoplasm of WT and RMS. This study shows that PAX2 is a sensitive marker of WT (sensitivity 97%), but PAX2 shows weak-to-moderate-intensity nuclear staining of RMS and B-cell ALL, somewhat limiting its utility. However, PAX2 may be a helpful marker in certain diagnostic situations. We speculate that RMS and B-cell ALL staining could be due to antibody cross-reactivity with PAX family members with known expression in RMS and B-cell ALL.
authors: Department of Pathology, Oregon Health & Science University, Portland, OR 97239-3098, USA.
authors: Jessica L
authors: JL
authors: Davis
authors: Linh
authors: L
authors: Matsumura
authors: Douglas A
authors: DA
authors: Weeks
authors: Megan L
authors: ML
authors: Troxell
mesh_terms: D000293:Adolescent; D014408:Biomarkers, Tumor / Q000032:analysis*; D001859:Bone Neoplasms / Q000737:chemistry; D001932:Brain Neoplasms / Q000737:chemistry; D002648:Child; D002675:Child, Preschool; D004847:Epithelial Cells / Q000737:chemistry; D006801:Humans; D007150:Immunohistochemistry; D007680:Kidney Neoplasms / Q000737:chemistry* / Q000473:pathology; D009447:Neuroblastoma / Q000737:chemistry; D018242:Neuroectodermal Tumors, Primitive / Q000737:chemistry; D051762:PAX2 Transcription Factor / Q000032:analysis*; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000378:metabolism; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012208:Rhabdomyosarcoma / Q000737:chemistry; D012512:Sarcoma, Ewing / Q000737:chemistry; D017154:Stromal Cells / Q000737:chemistry; D009396:Wilms Tumor / Q000737:chemistry* / Q000473:pathology
chemical_list: D014408:Biomarkers, Tumor; D051762:PAX2 Transcription Factor; C497318:PAX2 protein, human