B-cell specific activation protein encoded by the PAX-5 gene is commonly expressed in merkel cell carcinoma and small cell carcinomas.
PAX-5 is a B cell specific transcription factor crucial for B cell ontogeny and has been detected in most of human B-cell lymphomas. In mouse, PAX-5 is also highly expressed in the central nervous system under tight temporal and spatial controls during embryogenesis. In humans, however, detection of PAX-5 in cells other than B lymphocytes has rarely been reported. We have encountered cases of Merkel cell carcinoma expressing PAX-5 during our routine evaluation of lymphoma. Because Merkel cell carcinoma is a small blue round cell tumor constantly in the differential diagnosis of lymphoma, we expanded our study in an effort to determine if PAX-5 is significantly expressed in neuroendocrine tumors. Based on our immunohistochemistry results using a monoclonal anti-PAX5 antibody with paraffin-embedded tissue sections, we report herein that PAX-5 was detected in 29 of 31 (93.5%) of Merkel cell carcinoma and 22 of 30 (73.3%) of small cell carcinoma, but in none of 17 cases of carcinoid tumor. Furthermore, the staining intensity of PAX-5 in Merkel cell carcinoma was frequently comparable with that in most B-cell lymphomas. We conclude that expression of PAX-5 is not confined to the B cell lineage and is frequently associated with neuroendocrine carcinomas.
Dong
Henry Y
HY
Genzyme Genetics/IMPATH, New York, NY 10019, USA. henry.dong@impath.com
Liu
Wei
W
Cohen
Patti
P
Mahle
Christina E
CE
Zhang
Weisu
W
D001402:B-Lymphocytes / Q000378:metabolism* / Q000473:pathology; D014408:Biomarkers, Tumor / Q000378:metabolism; D002276:Carcinoid Tumor / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D015266:Carcinoma, Merkel Cell / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D018288:Carcinoma, Small Cell / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005770:Gastrointestinal Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D008175:Lung Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D051757:PAX5 Transcription Factor; D012333:RNA, Messenger / Q000378:metabolism; D012334:RNA, Neoplasm / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012878:Skin Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D014408:Biomarkers, Tumor; D004268:DNA-Binding Proteins; D051757:PAX5 Transcription Factor; C497281:PAX5 protein, human; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D014157:Transcription Factors