Cytological characteristics of invasive micropapillary carcinoma of the breast

Abstract

Objective : Aim of study was to classify the cytological features of invasive micropapillary carcinoma (IMPC) of the breast.
Study Design : We reviewed the cytological features in 7 cases of pathologically diagnosed IMPC in our hospital and related institutions between 2007 and 2014. These cytological specimens were studied to evaluate the cell cluster and nuclear pattern. Tumor cells in the cytological specimens were confirmed by epithelial membrane antigen (EMA).
Results : IMPC was diagnosed cytologically in five out of seven cases. The cytological characteristics of IMPC were as follows, 1) uniform size of cellular clusters, 2) appearance of pseudopapillary and mirror ball cell clusters, 3) the cellular polarity for outside of the clusters, 4) nuclear grade, 1 to 2, and 5) Nuclear size<10 μm nuclear size. IMPC could not be diagnosed in two cases, which showed, 1) variable cellular cluster size, 2) appearance of solid clusters, 3) not Papanicolaou stain, but an uncertain cellular polarity, 4) high nuclear grade, and 5) nuclear size>10 μm.
Conclusions : IMPC was able to be diagnosed cytologically in 70% (5 out of 7) of the cases. For the remaining 30% (2 out of 7) cases, they lacked the characteristic cytological findings. Careful attention should be paid in all cases to achieve a definitive diagnosis.