Introduction: Flat epithelial atypia (FEA) is a descriptive term that encompasses lesions of breast terminal duct lobular unit in which variably dilated acini with cyst formation are lined by one to several cell layers display low grade cytologic atypia. It is considered to be one of earlier premalignant breast lesions. The cyclin D1 is known to play an important role in the Gl/S check point of the cell cycle and its overexpression has been correlated with progression of breast cancer. The estrogen receptor (ER) level determinate the proliferative activity of cells which could be bearing on the development of premalignant and malignant breast lesions. It has been postulated that the effect of cyclinDl in cooperation with ER exert effects on mammary carcinogenesis.
Aim of work: this work was aimed to determine the cyclinDl and ER expression in flat epithelial atypia and correlate with other premalignant and malignant breast lesions in order to evaluate the relationship between duct carcinoma and the presence of coexistent flat epithelial atypia which could provide insight into connection between both lesions.
Materials and Methods: Paraffin blocks from 80 cases of breast lesions including 15 cases of ductal carcinoma in situ ( DCIS) , 30 cases of invasive duct carcinoma(IDC) and 27 cases of fibrocystic disease of breast( FCD) with usual ductal hyperplasia( UDH) and 8 cases of atypical ductal hyperplasia ( ADH) were collected. Examination of serial stained H&E sections were carried out and the association between the presence of FEA and these lesions was determined, Immunohistochemistry has been used to assess cyclinDl and ER expression in FEA and its relation to different breast lesions enclosing it. Adjacent terminal duct lobular unit (TDLU) of normal breast tissue were analyzed and served as control. The relationship between cyclinDl expression and differentiation of DCIS and IDC cases and the interrelationship between cyclinDl expression and ER in this group of cases was examined. The expression of these markers in cases of atypical ductal hyperplasia! ADH) has been compared with the expression seen in FEA, DCIS,IDC and FCD.
Results: Twelve cases of flat epithelial atypia was detected in association with following lesions as follow 6 cases with DCIS , 5 cases with IDC and one case with FCD but none was seen with ADH. Cases of duct carcinoma are of low grade category. CyclinDl overexpression was observed in 8 /12(75%) cases of FEA, in 0/15(66.7%) cases of DCIS, in 11/30(36.6%) cases of IDC and l/8(12.5/o) case of ADH. Overexpression was not observed in breast lobules ( type l and type2/3) and FCD with usual ductal hyperplasia. FEA had cyclinDl expression similar to that expressed by the lesion harboring it. The overexpression of cyclinDl in FEA lesions and in low grade DCIS was higher than that of ADH lesions and the difference was statistically significant ( p