Invasive breast carcinoma with lobular involvement. Frequency and location of lobular carcinoma in situ.

Abstract

This paper demonstrates lobular involvement of two morphological different types: Lobular carcinoma in situ and carcinomatous extension to the lobule in 70 non-selected cases of invasive breast carcinoma. Carcinomatous involvement of the lobules was found in 34 cases. In 16 of these cases, it was not possible to distinguish the lobular changes morphologically from lobular carcinoma in situ whereas, in 13 cases, carcinomatous extension to the lobules was found. In 5 cases the type of carcinomatous involvement of the lobules could not be established with certainty. In the 16 cases with lobular carcinoma in situ, 5 of the lesions were found at the edge of the invasive carcinoma, 4 were completely outside the tumour area, and in 7 cases the lesions were found both at the edge and completely outside the tumour area. In 59 per cent of cases the lesions were multicentric. Thirteen of the 16 cases presented lobular carcinoma in situ also in the upper quadrants. The diameter of the tumour was not related to the occurrence of lobular carcinoma in situ or to carcinomatous extension to the lobules. On the other hand, lobular carcinoma in situ was most frequent in highly differentiated carcinomas. A more detailed study of the biology of lobular carcinoma in situ, associated with invasive breast carcinoma, is considered necessary.