2024 Volume 63 Issue 5 Pages 235-240
Background : Lobular carcinoma in situ (LCIS) of the breast is rarely identified in cytology specimens so that little is known about its cytologic features. Herein, we report the cytologic findings in a case of LCIS of the breast diagnosed by histopathology.
Case : A woman in her 40 s noticed a mass in the EB portion of the right mammary gland. A fine-needle aspiration cytology specimen showed many crowding, overlapping, or sheet-like clusters of atypical epithelial cells. The cells had nearly uniform small-to medium-sized hyperchromatic nuclei and prominent nucleoli, some myoepithelial cells, and scattered single atypical epithelial cells. In the clusters or monolayered sheets of cells, the epithelial cells were non-cohesive, with slit-like spaces between them. Histopathologic examination of the resected specimen following right partial mastectomy revealed enlarged ductal and lobular glands filled with E-cadherin-negative uniform-sized tumor cells with comedo necrosis, which confirmed the diagnosis of florid LCIS.
Conclusion : Cytology smears prepared from invasive lobular carcinomas are usually sparse and have linear arrangements and the absence of these cytologic findings may help in distinguishing invasive lobular carcinoma from LCIS. Differentiating LCIS from ductal carcinoma is difficult, but the detection of slit-like spaces among the non-cohesive tumor cells arranged in monolayered sheets may be helpful for the diagnosis.
