Letters to the Editor
p40 (DNp63), a Lung Squamous Cell Marker, Can Also Be Used to Label Breast Myoepithelial Cells To the Editor.—Monoclonal p63 (4A4) antibody is conventionally used to mark lung squamous cell carcinoma. However, it also weakly stains the nuclei of up to 30% of lung adenocarcinomas. Another antibody, p40, recognizes DNp63, which is a p63 isoform. In a 2012 study,1 p40 was shown to be much more specific than p63, and
584 Arch Pathol Lab Med—Vol 138, May 2014
recent expert advisories suggest that it could replace p63 as a marker of lung squamous cell carcinoma.2 Cost control has become a major factor in contemporary practice, and reducing inventory of redundant antibodies, while increasing the number of uses of antibodies remaining on inventory, is an important way of controlling costs. In addition to lung squamous cell carcinoma, p63 is also commonly used to label breast myoepithelial cells. Our community hospital laboratory, which is under a supply and service contract with a company that does not manufacture p63, has been purchasing it from Biocare Medical (Walnut Creek, California), which is 1 of 2 companies that can market p63 in the United States (Ventana Medical Systems, Tucson, Arizona, is the other one). Biocare Medical also holds exclusive license for marketing p40 in the United States. Given our concerns about costs, and the fact that p40 is an antibody to a p63 isoform known to label breast myoepithelial cells,3 we wondered whether monoclonal p40 could replace p63 entirely for these 2 purposes. We tested 10 cases of excision biopsy for breast carcinoma, selecting blocks that contained invasive carcinoma, in situ carcinoma, and proliferative fibrocystic change, and stained them with both monoclonal p63 (4A4) and monoclonal p40 (DNp63), at similar dilutions. We reviewed cases blind to knowledge of antibody. The results demonstrated no difference in the staining pattern of the antibodies, in that they both specifically highlighted the nuclei of myoepithelial cells. Because this is far from a definitive explication of relative sensitivities and specificities of the 2
antibodies, we retain other myoepithelial cell–highlighting antibodies such as CD10, which we use as part of a panel.4 We note that the original investigations1 used polyclonal rather than monoclonal p40. We do not anticipate results being substantially different with the polyclonal antibody. The findings of this limited study indicate that monoclonal p40 may be used instead of p63 for the purposes of highlighting breast myoepithelial cells in addition to assisting in the diagnosis of lung squamous cell carcinoma. Community hospital laboratories like ours could benefit from eliminating an antibody from their inventory, while retaining the ability to make accurate diagnoses. RAKESH SARDA, MD JEAN TAYLOR, HT (ASCP) QIHC Meriter Laboratories Meriter Hospital Madison, WI 53711 1. Bishop JA, Teruya-Feldstein J, Westra WH, Pelosi G, Travis WD, Rekhtman N. p40 (DNp63) is superior to p63 for the diagnosis of pulmonary squamous cell carcinoma. Mod Pathol. 2012;25(3): 405–415. 2. Travis WD, Brambilla E, Noguchi M, et al. Diagnosis of lung cancer in small biopsies and cytology: implications of the 2011 International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society Classification. Arch Pathol Lab Med. 2013;137(5):668– 684. 3. Barbareschi M, Pecciarini L, Cangi MG, et al. p63, A p53 homologue, is a selective nuclear marker of myoepithelial cells of the human breast. Am J Surg Pathol. 2001;25(8):1054–1060. 4. Dewar R, Fadare O, Gilmore H, Gown AM. Best practices in diagnostic immunohistochemistry: myoepithelial markers in breast pathology. Arch Pathol Lab Med. 2011;135(4):422–429.
The authors have no relevant financial interest in the products or companies described in this article.
doi: 10.5858/arpa.2013-0414-LE
Letters to the Editor
Copyright of Archives of Pathology & Laboratory Medicine is the property of College of American Pathologists and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.
p40 (DNp63), a Lung Squamous Cell Marker, Can Also Be Used to Label Breast Myoepithelial Cells To the Editor.—Monoclonal p63 (4A4) antibody is conventionally used to mark lung squamous cell carcinoma. However, it also weakly stains the nuclei of up to 30% of lung adenocarcinomas. Another antibody, p40, recognizes DNp63, which is a p63 isoform. In a 2012 study,1 p40 was shown to be much more specific than p63, and
584 Arch Pathol Lab Med—Vol 138, May 2014
recent expert advisories suggest that it could replace p63 as a marker of lung squamous cell carcinoma.2 Cost control has become a major factor in contemporary practice, and reducing inventory of redundant antibodies, while increasing the number of uses of antibodies remaining on inventory, is an important way of controlling costs. In addition to lung squamous cell carcinoma, p63 is also commonly used to label breast myoepithelial cells. Our community hospital laboratory, which is under a supply and service contract with a company that does not manufacture p63, has been purchasing it from Biocare Medical (Walnut Creek, California), which is 1 of 2 companies that can market p63 in the United States (Ventana Medical Systems, Tucson, Arizona, is the other one). Biocare Medical also holds exclusive license for marketing p40 in the United States. Given our concerns about costs, and the fact that p40 is an antibody to a p63 isoform known to label breast myoepithelial cells,3 we wondered whether monoclonal p40 could replace p63 entirely for these 2 purposes. We tested 10 cases of excision biopsy for breast carcinoma, selecting blocks that contained invasive carcinoma, in situ carcinoma, and proliferative fibrocystic change, and stained them with both monoclonal p63 (4A4) and monoclonal p40 (DNp63), at similar dilutions. We reviewed cases blind to knowledge of antibody. The results demonstrated no difference in the staining pattern of the antibodies, in that they both specifically highlighted the nuclei of myoepithelial cells. Because this is far from a definitive explication of relative sensitivities and specificities of the 2
antibodies, we retain other myoepithelial cell–highlighting antibodies such as CD10, which we use as part of a panel.4 We note that the original investigations1 used polyclonal rather than monoclonal p40. We do not anticipate results being substantially different with the polyclonal antibody. The findings of this limited study indicate that monoclonal p40 may be used instead of p63 for the purposes of highlighting breast myoepithelial cells in addition to assisting in the diagnosis of lung squamous cell carcinoma. Community hospital laboratories like ours could benefit from eliminating an antibody from their inventory, while retaining the ability to make accurate diagnoses. RAKESH SARDA, MD JEAN TAYLOR, HT (ASCP) QIHC Meriter Laboratories Meriter Hospital Madison, WI 53711 1. Bishop JA, Teruya-Feldstein J, Westra WH, Pelosi G, Travis WD, Rekhtman N. p40 (DNp63) is superior to p63 for the diagnosis of pulmonary squamous cell carcinoma. Mod Pathol. 2012;25(3): 405–415. 2. Travis WD, Brambilla E, Noguchi M, et al. Diagnosis of lung cancer in small biopsies and cytology: implications of the 2011 International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society Classification. Arch Pathol Lab Med. 2013;137(5):668– 684. 3. Barbareschi M, Pecciarini L, Cangi MG, et al. p63, A p53 homologue, is a selective nuclear marker of myoepithelial cells of the human breast. Am J Surg Pathol. 2001;25(8):1054–1060. 4. Dewar R, Fadare O, Gilmore H, Gown AM. Best practices in diagnostic immunohistochemistry: myoepithelial markers in breast pathology. Arch Pathol Lab Med. 2011;135(4):422–429.
The authors have no relevant financial interest in the products or companies described in this article.
doi: 10.5858/arpa.2013-0414-LE
Letters to the Editor
Copyright of Archives of Pathology & Laboratory Medicine is the property of College of American Pathologists and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.
