Other rare variants of Breast Carcinoma
Apocrine carcinoma is a morphologic variant of ductal carcinoma. FNA smears contain numerous epithelial cells arranged in syncytial fragments along with individually scattered cells. The cells show apocrine features, consisting of abundant basophilic to eosinophilic granular cytoplasm and large nuclei with prominent nucleoli. It can be difficult to differentiate from atypical apocrine metaplasia. Moreover, apocrine carcinoma is usually triple-negative.
Smears of this rare variant of breast carcinoma consist of large irregular sheets of malignant polygonal cells with granular to vacuolated cytoplasm. The presence of grape-like clusters of vacuolated cells is a helpful diagnostic feature.
Squamous cell carcinoma and metaplastic carcinoma
Low-grade adenosquamous carcinoma is characterized by a low-rate of FNA specimens. Glandular cells are regular and squamous cell are rare. Pure squamous cell carcinoma is very rare in the breast, although a malignant squamous component may occasionally be present in ductal carcinoma. FNA smears show well to poorly differentiated malignant squamous cells, with cytoplasmic keratinisation and intercellular bridges. The cells are arranged in sheets or syncytial groupings or scattered individually. Smears in spindle cell carcinomas are usually hypercellular and are similar to those from spindle cell sarcomas. Finally in chondroid and osteoid variants of metaplastic carcinoma, smears resemble polymorphous sarcoma rich in chondroid/osteoid matrix.
This is a very rare variant of breast carcinoma, resulting in a cystic mass which usually persists after aspiration of a typically haemorragic fluid. Cytological smears are extremely cellular, with mildly atypical cells arranged in loosely cohesive groups and papillary clusters.