Antibodies targeting p63 react specifically in the cytoplasm of breast epithelial cells exhibiting secretory differentiation.
OBJECTIVE
The nuclear detection of p63 in myoepithelial cells of the breast has been useful in identifying possibly invasive carcinomas. While examining myoepithelial cells for p63 a very strong cytoplasmic reaction product was noted in secretory cells. The aim was to determine whether this reaction is specific for p63 and indicative of all breast secretory cells.


METHODS
Thirty breast specimens were tested immunohistochemically for p63 protein. These included seven with benign secretory changes, 10 secretory carcinomas (nine invasive), one microglandular adenosis, three lobular neoplasias, four invasive ductal carcinomas, three clear cell carcinomas, one squamous cell carcinoma and one mucinous carcinoma.


RESULTS
Only cells exhibiting secretory changes or secretory carcinoma were cytoplasmically reactive for p63. The positive reaction was also present as an intraluminal secretory product. This reaction was not seen in cells undergoing apocrine differentiation or in other cells containing secretory vacuoles.


CONCLUSIONS
Cells with secretory changes contain p63 protein or an antigenic equivalent. The detection of p63 protein continues to have considerable value for the identification of myoepithelial cells and thus the determination of invasion, but will also have value in the determination of secretory carcinomas of the breast and in understanding their development.
Bratthauer
G L
GL
Department of Gynecologic and Breast Pathology, Armed Forces Institute of Pathology, Washington DC 20306, USA. bratthauer@afip.osd.mil
Saenger
J S
JS
Strauss
B L
BL
D018262:Adenocarcinoma, Clear Cell / Q000378:metabolism / Q000473:pathology; D002288:Adenocarcinoma, Mucinous / Q000378:metabolism / Q000473:pathology; D000906:Antibodies / Q000378:metabolism*; D001940:Breast / Q000166:cytology* / Q000378:metabolism*; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology; D002277:Carcinoma / Q000737:chemistry / Q000473:pathology; D002285:Carcinoma, Intraductal, Noninfiltrating / Q000378:metabolism / Q000473:pathology; D018275:Carcinoma, Lobular / Q000378:metabolism / Q000473:pathology; D002294:Carcinoma, Squamous Cell / Q000378:metabolism / Q000473:pathology; D002454:Cell Differentiation; D003593:Cytoplasm / Q000378:metabolism; D004268:DNA-Binding Proteins; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism; D005260:Female; D005348:Fibrocystic Breast Disease / Q000378:metabolism / Q000473:pathology; D016147:Genes, Tumor Suppressor; D006801:Humans; D007150:Immunohistochemistry; D009361:Neoplasm Invasiveness; D010750:Phosphoproteins; D015534:Trans-Activators; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins
D000906:Antibodies; D004268:DNA-Binding Proteins; D010750:Phosphoproteins; C115051:TP63 protein, human; D015534:Trans-Activators; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins