Cytologic findings in infiltrating micropapillary carcinoma and mucinous carcinomas with micropapillary pattern.
OBJECTIVE
To examine the observation that some mucinous carcinomas have a micropapillary pattern and are mucinous variants of the highly angioinvasive infiltrating micropapillary carcinomas (IMPC).


METHODS
We evaluated cytologic findings of 13 IMPC and 55 mucinous carcinomas for comparative features.


RESULTS
In mucinous carcinomas, 37 of 50 (74%) had a micropapillary pattern. This group included 27 cases with pure mucinous micropapillary morphology (MUMPC), 8 MUMPC associated with a ductal carcinoma of the IMPC type (MUIDC) and 2 cases of mixed mucinous carcinomas with an MUMPC and a solid variant ofpapillary carcinoma (SVPC) component. On cytology both IMPC and mucinous carcinomas with micropapillary pattern demonstrated the micropapillary pattern, that is, angulated clusters or abortive papillae and ball-like clusters. However, the IMPC smears revealed numerous singly scattered tumor cells and larger fragments with shrub-like branching and the MUMPC had psammoma bodies. The mixed MUMPC and SVPC showed the classic cytologic features of MUMPC admixed with abundant singly dispersed tumor cells in the background representing the SVPC component.


CONCLUSIONS
Although IMPC and the MUMPC share the micropapillary pattern on histologic examination, mucin alters the appearances in aspirates. Recognition of this morphologic spectrum will help in understanding the behavior of these tumors.
Madur
Bhulaxmi
B
Department of Pathology, Tata Memorial Hospital, Parel, Mumbai, India.
Shet
Tanuja
T
Chinoy
Roshni
R
D002288:Adenocarcinoma, Mucinous / Q000473:pathology* / Q000628:therapy; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000473:pathology* / Q000628:therapy; D018270:Carcinoma, Ductal, Breast / Q000473:pathology; D002291:Carcinoma, Papillary / Q000473:pathology* / Q000628:therapy; D017024:Chemotherapy, Adjuvant; D005260:Female; D006801:Humans; D008875:Middle Aged