Mammographically detected in situ lobular carcinomas of the breast

We present ten cases of mammographically detected lobular carcinoma in situ (LCIS), involving a single area of variable size (up to a quadrant) in sev en cases and the entire gland in three cases. Histologically, calcification s were associated with necrotic central areas within the in situ carcinomat ous foci. Multiple foci of LCIS were observed in all five cases in which ma stectomy had been performed. Cytologically, the lesions were characterized by a solid proliferation of round noncohesive cells with nuclei of intermed iate size. Immunocytochemically, all cases were E-cadherin and p53 negative , and c-ErbB-2, GCDFP-15 and estrogen receptor positive. The proliferation index, evaluated with Ki67, was in the low range. Four cases were associate d with foci of infiltrating lobular carcinoma (ILC). These findings contrad ict the commonly held opinion that LCIS is not mammographically detectable because of its lack of necrosis and calcification. This study documents the existence of a variant of LCIS exhibiting the mammographic features and ce ntral necrosis classically associated with ductal carcinoma in situ (DCIS), while retaining the spatial distribution, cytological composition and immu nocytochemical features of lobular carcinoma.