DIAGNOSTIC VALUE OF LAMININ IN DIFFERENTIATION BETWEEN BENIGN AND MALIGNANT EPITHELIAL LESIONS OF THE BREAST

Abstract

Breast cancer is the most common malignancy in females in Egypt accounting for 25 % of all malignancies in Egyptian women. (El Bolkainy, 1991)

Laminin, a major glycoprotein of the basement membrane has been found to play significant roles during invasion and metastasis in breast cancer. (Castronovo et aL, 1991)

Immunohistochemical investigations of different breast lesions have shown general reduction or loss ofthe basement membrane laminin stammg in invasive carcinomas, while benign lesions were always characterized by a continuous laminin staining of the basement membrane. (Christensen, 1992)

In this study, a trial was done to evaluate the role of laminin in differentiating between benign and malignant epithelial breast lesions and to evaluate its possible relation to the tumor size, tumor grade, and lymph node status, features which may be useful in the assessment of the prognostic outcome of breast carcinoma.

The present work comprised 50 cases of different breast lesions including 18 benign (36 %) and 32 malignant (64 %) lesions. Paraffin blocks of these cases were randomly collected from the Pathology Department of Ain Shams Specialized Hospital during the period from 1998 to 2001.

Paraffin sections from all the examined lesions were stained by haematoxylin and eosin for routine examination and other corresponding sections were stained immuno­ histochemically for laminin.

The benign lesions included 12 cases of fibrocystic disease, 3 fibroadenomas, and 3 intraductal papillomas. The malignant lesions included 26 cases (81.6 %) of ductal carcinoma and 6 cases (18.7 %) of lobular carcinomas. Six cases of the ductal carcinoma (23 %) were pure ductal carcinoma in situ.

The infiltrating ductal carcinomas were classified as follows: three cases (15 %) as grade I, twelve cases (60 %) as grade II, and five cases (25 %) as grade III.

In all the benign lesions, the basement membrane laminin staining was continuous and linear, while none of the invasive carcinomas showed a continuous basement membrane staining. The laminin staining was markedly disrupted in 38.5 % of the invasive carcinomas and was completely absent in the other 61 .5 %.

Four cases of the intraductal carcinomas exhibited a continuous basement membrane staining, while in the other two cases, the laminin staining was focally disrupted and there were small breaks present in the basement membrane.

No significant correlation was present between the basement membrane laminin-staining pattern neither with the patient' s age nor with the tumor type.

On the other hand , there ha ve been sign i ficant correlations present between the pattern of the basement

membrane laminin stammg and the tumor size, the tumor grade, and the lymph node status. Laminin staining tended to be present more in well differentiated and in small sized tumors than in poorly differentiated, and large sized tumors. Lymph node negative tumors expressed basement membrane laminin more than lymph node positive tumors.

From the previous results, we conclude that the immunohistochemical staining by laminin could be used in differentiating benign epithelial lesions and carcinoma in situ from invasive carcinomas.

Laminin immunostaining of breast carcinoma may be also used in the detection of small foci of microinvasion, and it could be of some help as a good prognostic factor of breast carcinoma.