Breast carcinoma with osteoclast-like giant cells: A cytological-pathological correlation with a literature review.

Breast carcinoma with osteoclast-like giant cells (OGCs) is a rare disease characterized by the infiltration of OGCs in the tumor; however, cytological aspects of this tumor type remain elusive. We examined the cytological features in fine needle aspiration (FNA) biopsy smears obtained from 5 patients who were histologically diagnosed with breast carcinoma with OGCs. We compared FNA and clinicopathological findings with results from the published literature. Histological assessment of the resected samples showed that all tumors exhibited a histological grade 1 phenotype with a predominant cribriform architecture. Four patients were estrogen receptor positive, and 1 patient showed a triple negative phenotype. All patients survived without tumor recurrence. In the FNA smears, tumor cells were arranged in loosely cohesive clusters, characterized by varying degrees of OGCs infiltration and rare formation of solid tumor nests. Occasionally, 2- or 3-dimensional clusters of tumor cells were found, accompanied by OGCs at the peripheral regions. In all patients, tumor cells were small without severe nuclear atypia. None of the patients showed significant background necrosis. In summary, cytological features of breast carcinoma with OGCs are characterized by loose aggregates of low grade tumor cells, the presence of OGCs, and the absence of necrosis, all of which were consistent with features reported previously. This peculiar form of breast tumors should be included in the differential diagnosis, when physicians encounter FNA findings including low grade ductal carcinoma with the admixture of multinucleated giant cells or OGCs.