Histiocytoid invasive lobular carcinoma detected on a cervical smear: a case report of breast carcinoma metastasizing to the uterus

Among cases of breast carcinoma metastatic to the uterus, the percentage of these cases that are invasive lobular carcinoma (ILC) is higher than what may be expected when one considers the relative infrequency of ILC at the primary site. However, fewer than 10 cases of metastatic ILC of the breast detected in the cervical smear have been reported in the literature. Although several variants of ILC exist aside from classic ILC, previously reported ILC cases detected by cervical smear are probably not ILC variants because there was no description as variants of ILC in such cases. Herein, we present a case of a 52-year-old woman having a histiocytoid variant of ILC metastatic to the uterus that was detected on a conventional cervical smear. It is important to keep in mind that ILC can metastasize to the uterus, because its morphology is easily confused with a high-grade squamous intraepithelial lesion. Being aware of the possibility of metastatic ILC, non-high-grade nuclei of tumor cells with poorly differentiated appearance, namely loose cohesiveness, would lead to a more confident diagnosis.