title: CD20 negative primary diffuse large B cell lymphoma of breast: Role of Pax-5.
abstract: Pax-5 is a B cell marker, the expression of which is detectable in as early as the pro B stage, and subsequently, in all further stages of B cell development except the plasma cells. Malignant lymphomas of breast are uncommon and occur as either primary or secondary lesions. Primary lymphoma is a rare disorder of breast and constitutes less than 0.6% of all breast malignancies and 2.2% of extranodal lymphomas. We report an unusual case of CD20 negative Pax-5 positive primary diffuse large B cell lymphoma (DLBCL) of breast. The case highlights the diagnostic challenge posed by extranodal CD20 negative DLBCL. Pax-5 immunohistochemistry has diagnostic benefit as a B-cell marker in the work-up of undifferentiated malignant neoplasms. Although it is available for nearly a decade now, it is not widely used. Pax-5 is a valuable addition to the armamentarium of markers currently available for lymphoma subtyping.
authors.affiliation: Department of Pathology, Dr. Ram Manohar Lohia Institute of Medical Sciences, Lucknow, Uttar Pradesh, India.
authors.forename: Saumya
authors.initials: S
authors.lastname: Shukla
authors.forename: Namrata Punit
authors.initials: NP
authors.lastname: Awasthi
authors.forename: Pradyumn
authors.initials: P
authors.lastname: Singh
authors.forename: Nuzhat
authors.initials: N
authors.lastname: Husain
mesh_terms: D000328:Adult; D018951:Antigens, CD20 / Q000378:metabolism*; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D014408:Biomarkers, Tumor / Q000378:metabolism; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000188:drug therapy / Q000378:metabolism; D005260:Female; D006801:Humans; D016403:Lymphoma, Large B-Cell, Diffuse / Q000175:diagnosis* / Q000188:drug therapy / Q000378:metabolism; D051757:PAX5 Transcription Factor / Q000378:metabolism*
chemical_list: D018951:Antigens, CD20; D014408:Biomarkers, Tumor; D051757:PAX5 Transcription Factor; C497281:PAX5 protein, human