| Abstract | Background and Purpose: The pattern and distribution
of p63 expression as a myoepithelial/basal stem cell marker
can be different between atypical ductal hyperplasia
(ADH), ductal carcinoma in situ (DCIS) and invasive
ductal carcinoma (IDC) and may denote basal phenotype
of breast ductal carcinoma. CK8/18 is a luminal marker
and may indicate a luminal phenotype of IDC and its
expression in ADH and DCIS may refer to a possible
precursor lesion to IDC. This work was designed to study
and compare the expression of p63 and cytokeratin 8/18
(CK8/18) in some cases of ADH, DCIS and IDC.
Materials and Methods: Histopathological evaluation
and immunohistochemical study of anti-p63 and anti-
CK8/18 was performed on selected archival cases of 7
ADH, 12 DCIS, 30 IDC of known clinicopathological
data and previous estrogen receptor status (ER) for IDC.
Confirmatory anti-smooth muscle actin (ASMA) expression
for positive p63 cases was performed.
Results: p63 was expressed in the peripheral rim of
the myoepithelial cell layer in ADH and DCIS with occasional
gabs in DCIS. It was positive and stained occasional
malignant cells in 3/30 (10%) of IDC cases. Confirmatory
ASMA staining decorated the same peripheral rim of cells
in ADH and DCIS, but was negative in p63 positive IDC
cases. CK8/18 was positive in 100% of ADH, 8/12 (66.7%)
of DCIS and 22/30 (73%) of IDC cases. Combined p63
and CK8/18 expression was noticed in 3/30 (10%) of IDC.
Conclusion: It is concluded from this study that p63
is specific and valuable in differentiating myoepithelial
cells and is more specific and valuable than other myoepithelial
markers, as ASMA and can differentiate between
ADH, DCIS, IDC as it stains peripheral myoepithelial
cells in ADH and DCIS with gabs in the latter and does
not stain any neoplastic cells. In IDC, it is positive in
malignant cells in a minority of cases which may indicate basal/stem cell/myoepithelial cell origin of breast carcinoma.
Comparatively, CK8/18 cannot differentiate ADH,
DCIS and IDC as there is no difference in its staining
pattern among them, which may suggest that they are a
continuum or that ADH and DCIS are precursors for the
luminal phenotype of IDC. |