Significance of squamous cells in fine needle aspiration cytology of the breast. A review of cases in a seven-year period.
OBJECTIVE
To delineate the significance of detecting squamous cells in fine needle aspiration biopsy of breast lesions.


METHODS
The authors reviewed 15 cases of fine needle aspiration cytology of the breast with a discernible number of squamous cells from the files of Pamela Youde Nethersole Eastern Hospital, Hong Kong, during a seven-year period from the start of 1994 to the end of 2001. The cytologic features were correlated with clinical, radiologic and histologic findings, if any.


RESULTS
Among the 15 fine needle aspirates of the breast with a discernible number of squamous cells, 5 of them represented metaplastic carcinoma. The remaining consisted of 3 cases of fibroepithelial tumors, 1 case of duct ectasia, 3 cases of subareolar abscess, 2 cases of sclerosed intraduct papilloma and 1 case of benign breast cyst. In general, benign squamous cells were bland looking and often associated with anucleated squames. They were mitotically inactive and could show a good maturation pattern. Tumor cell cannibalism was rare. The presence of abundant, foamy macrophages in the background suggested a benign lesion. The primary diagnosis could be deduced by recognition of other features, such as the presence of myxoid stromal tissue and papillary structures. In contrast, malignant squamous cells in metaplastic carcinoma were more pleomorphic and mitotically active. Dyskeratosis and tumor cell cannibalism were obvious. Tumor diathesis and bizarre-shaped cells were sometimes found.


CONCLUSIONS
Squamous cells occur in fine needle aspirates from a number of benign and malignant breast lesions. Benign conditions with abundant squamous cells may sometimes mimic malignant squamous lesions and vice versa. Careful assessment of the cytologic features of squamous cells and background appearance is crucial for achieving a correct diagnosis.
Ng
Wai-Kuen
WK
Departments of Pathology and Surgery, Pamela Youde Nethersole Eastern Hospital, 3 Lok Man Road, Chai Wan, Hong Kong, S.A.R., China. ngwk@ahoo.com
Kong
James H B
JH
D000038:Abscess / Q000175:diagnosis / Q000473:pathology; D000293:Adolescent; D000328:Adult; D000368:Aged; D001707:Biopsy, Needle; D001941:Breast Diseases / Q000175:diagnosis* / Q000473:pathology; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000473:pathology; D002294:Carcinoma, Squamous Cell / Q000175:diagnosis / Q000473:pathology; D003560:Cysts / Q000175:diagnosis / Q000473:pathology; D003937:Diagnosis, Differential; D004108:Dilatation, Pathologic / Q000175:diagnosis / Q000473:pathology; D004847:Epithelial Cells / Q000473:pathology*; D005260:Female; D006801:Humans; D008679:Metaplasia; D008875:Middle Aged; D018225:Neoplasms, Fibroepithelial / Q000175:diagnosis / Q000473:pathology; D018300:Papilloma, Intraductal / Q000175:diagnosis / Q000473:pathology; D012598:Sclerosis