bromochloroacetic-acid and Adenomyoepithelioma

Two cases of adenomyoepithelioma of the breast with malignant transformation by monophasic population of cells are presented. The underlying benign adenomyoepithelioma with typical biphasic architectural pattern was identified and represented at least 30% of the tumor in each case. In both cases, malignant portion of tumor was composed of relatively uniform monophasic population of highly atypical cells. The malignant component in case 1 was positive for pan cytokeratin, myoepithelial markers, and basal-type cytokeratins and also focally positive for luminal-type of cytokeratins, but negative for hormone receptors (estrogen and progesterone) and HER-2/neu protein overexpression. The malignant component in case 2 was positive for spectrum of myoepithelial markers but negative for luminal cytokeratins, hormone receptors and HER-2/neu protein overexpression. The bilinear immunophenotype in the case 1 suggests that the malignant tumor may have developed from precursor multipotent cells that can differentiate into both luminal epithelial and myoepithelial cells, although malignant component in case 2 appears to be the of pure myoepithelial phenotype.

Topics: Adenomyoepithelioma; Adult; Breast Neoplasms; Cell Transformation, Neoplastic; Female; Humans; Keratins; Middle Aged

To determine which immunohistochemical markers are useful for the identification of neoplastic myoepithelial cells in adenomyoepithelioma of the breast, the expression of seven myoepithelial markers (α-smooth muscle actin (α-SMA), calponin, p63, CD10, cytokeratin 5/6, cytokeratin 14, and S-100) was examined in 19 lesions from 16 patients. The lesion consisted of seven spindle and 12 clear cell lesions. For normal myoepithelial cells, α-SMA, calponin, and p63 were significantly more sensitive than cytokeratin 5/6, cytokeratin 14, and S-100. There was no significant difference in the expression of α-SMA, calponin, p63, and CD10 in neoplastic myoepithelial cells of adenomyoepithelioma regardless of spindle or clear cell types. In spindle cell lesions, high-molecular weight cytokeratins (HMWCK; cytokeratin 5/6 and cytokeratin 14) tended to show higher staining scores and S-100 showed lower staining scores than other markers. In clear cell lesions, HMWCK showed significantly lower staining scores than the other five markers. There was no significant difference in staining scores among the other five markers. HMWCK showed a unique paradoxical staining pattern in clear cell lesions, with diffusely positive inner epithelial cells and completely negative outer myoepithelial cells. Although the sensitivity of HMWCK in clear cell lesions is low, with this unique paradoxical staining pattern and relatively high sensitivity in spindle cell lesions, HMWCK could be useful in diagnosing adenomyoepithelioma. In choosing immunohistochemical markers, any of the seven markers are useful, but combining HMWCK and any one of α-SMA, calponin, and p63 would be a good panel for the diagnosis of adenomyoepithelioma.

Topics: Adenomyoepithelioma; Biomarkers, Tumor; Breast Neoplasms; Female; Humans; Immunohistochemistry; Keratins