Use of p63 and CD10 in the differential diagnosis of papillary neoplasms of the breast.

Papillary neoplasms of the breast represent a complex spectrum ranging from benign to malignant lesions. The myoepithelial cell (MEC) layer is generally continuous in papillomas and increasingly discontinuous to absent in atypical and malignant counterparts. Identification of MECs can be difficult on morphological grounds and currently relies on immunomarkers. We investigated the potential role of p63 and CD10 in 20 papillary lesions and compared them with 1A4 and calponin. In 18 cases, adjacent normal breast tissue was available for study. All four markers were diffusely positive in all samples of normal tissue and benign papillomas indicating similar sensitivity in the identification of MECs. Intense positivity was found in 100% of the cases with 1A4 and CD10, but in only 76% with calponin and in 60.5% with p63 (differences statistically significant, p < 0.05), suggesting that the former two render more reproducible results. The most specific markers were p63 and CD10 which showed cross-reactivity in 0% and in up to 33% of the cases respectively. 1A4 and calponin showed diffuse cross-reactivity in all cases. When assessing benign versus atypical papillomas, the best parameters were diffuse positivity using CD10 or p63, and continuous MEC layer, mainly using CD10. When comparing benign papillomas to carcinomas all parameters were equally useful with 1A4 and CD10. Regardless of the marker, intense positivity was the only parameter that could distinguish atypical papillomas from papillary carcinomas. p63 staining, which renders a nuclear and mostly discontinuous reactivity, was not as useful as the other markers when the parameter continuous MEC layer was evaluated. Although CD10 seems to combine the highest specificity and reproducibility with a good sensitivity, reproducibility of 1A4 is higher. Thus, a minimum panel to assess papillary lesions should include both markers. Although p63 is the most specific, its nuclear and discontinuous pattern may lead to erroneous diagnosis, especially in the differentiation between benign papillomas and atypical/malignant lesions.

p63 and CD10: reliable markers in discriminating benign sclerosing lesions from tubular carcinoma of the breast?

The immunohistochemical detection of myoepithelial cells in benign sclerosing lesions of the breast is useful in distinguishing them from tubular carcinoma. So far, this detection has been carried out using antibodies against cytoskeletal proteins, such as alpha-smooth muscle actin (1A4) and calponin. However, the specificity of these markers has been questioned since they may be expressed in stromal myofibroblasts and vascular smooth muscle. Recently, two novel myoepithelial markers have been described: the nuclear protein p63, a member of the p53 family, and the surface antigen CD10, also known as common acute lymphoblastic leukemia antigen (CALLA). The authors assessed the use of p63 and CD10 in the differential diagnosis between benign sclerosing lesions, such as sclerosing adenosis and radial scar, and tubular carcinoma, in comparison to the traditional myoepithelial markers 1A4 and calponin. p63, CD10, 1A4, and calponin were expressed in myoepithelial cells of all benign lesions and were consistently negative in all cases of tubular carcinoma. In contrast to cytoskeletal proteins, p63 and CD10 were mostly confined to myoepithelial cells and thus were more specific than the traditional counterparts. However, 1A4 was more intensely expressed and more reproducible than the novel markers. In conclusion, p63 and CD10 may be used as a complement to 1A4 in distinguishing benign sclerosing lesions from tubular carcinoma of the breast.