Fine needle aspiration cytology of invasive micropapillary carcinoma of the breast.
OBJECTIVE
To determine the pathognomonic diagnostic cytological features of invasive micropapillary carcinoma of the breast which is a poor prognostic subtype of infiltrating ductal carcinoma.


METHODS
A series of 20 histologically proven tumours were reviewed retrospectively to evaluate the various cytological features, including tumour morules, isolated malignant cells, staghorn epithelial structures, mucinous background and apocrine metaplasia.


RESULTS
Tumour morules formation and isolated malignant cells were the two most reliable and constant cytological features, being present in 75% (15/20 cases) of cases. Staghorn epithelial structures were present in 35% (7 cases). Mucinous background (2 cases, 10%) and apocrine metaplasia (4 cases, 20%) of the tumour cells were seen in a few cases only and did not appear very helpful.


CONCLUSIONS
Tumour morules formation, isolated malignant cells and staghorn epithelial structures are the most reliable cytological features, and the presence of these should raise suspicion of invasive micropapillary carcinoma.
Department of Anatomical and Cellular Pathology, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong. philiplui@cuhk.edu.hk
Philip C W
PC
Lui
Patrick P L
PP
Lau
Gary M K
GM
Tse
Puay Hoon
PH
Tan
Regina C L
RC
Lo
Victor W L
VW
Tang
Wai Kuen
WK
Ng
Anjali
A
Somali
Kong Ling
KL
Mak
Teresa M M
TM
Thomas
Ngot Htai
NH
Chan
Tin Tin
TT
Hiang
Norman H L
NH
Chan
D000328:Adult; D000368:Aged; D044963:Biopsy, Fine-Needle; D001943:Breast Neoplasms / Q000175:diagnosis / Q000473:pathology*; D002291:Carcinoma, Papillary / Q000175:diagnosis / Q000473:pathology*; D002449:Cell Aggregation; D004847:Epithelial Cells / Q000473:pathology; D005260:Female; D006801:Humans; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D010641:Phenotype; D011379:Prognosis; D012189:Retrospective Studies