Mastopathic fibroadenoma of the breast: a pitfall of aspiration cytology.
OBJECTIVE
To assess the correlation between cytological diagnoses and histological subtypes of fibroadenoma (FA) and to clarify the cytological features of a specific group of FA displaying variable features similar to fibrocystic disease (mastopathic type, MFA), and to evaluate the significance of this subtype in cytological diagnosis.


METHODS
A review of 141 cases of histologically proven FA was performed. We re-classified them into four subtypes according to Kinoshita's criteria [Jpn J Breast Cancer6 (1991) 377] and further selected 92 cases for which both fine needle aspiration (FNA) smears and histological specimens were available. Among them, 18 cases of MFA and their cytological smears were selected for the present study.


RESULTS
There was significant correlation between MFA and cytological diagnosis of 'indeterminate' or 'suspicious for malignancy' (P < 0.01). Although no false-positive diagnosis was experienced in our series, 56% of the MFAs (10/18) had cytological diagnoses of indeterminate or were included in the category 'suspicious for malignancy'. Smears from MFA revealed high cellularity (9/18 smears had more than 10 epithelial clusters each composed of more than 50 cells), presence of cellular discohesiveness (13/18, 72.2%), but only mild nuclear atypia (5/18, 27.8%). Anisonucleosis was present in fewer than half the cases and no apparent condensed chromatin was identified.


CONCLUSIONS
We highlight the significance of subclassification of MFA in aspiration cytology of breast. MFA had a significantly higher chance of falling into the 'suspicious for malignancy' or 'indeterminate' diagnostic category in aspiration cytology. It might be a diagnostic challenge for cytopathologist to identify this subtype of FA in FNA smears.
Mori
I
I
Department of Human Pathology, Wakayama Medical University, Wakayama City, Wakayama, Japan. ichiro-m@wakayama-med.ac.jp
Han
B
B
Wang
X
X
Taniguchi
E
E
Nakamura
M
M
Nakamura
Y
Y
Bai
Y
Y
Kakudo
K
K
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D044963:Biopsy, Fine-Needle; D001943:Breast Neoplasms / Q000145:classification* / Q000473:pathology*; D003937:Diagnosis, Differential; D005260:Female; D018226:Fibroadenoma / Q000145:classification* / Q000473:pathology*; D005348:Fibrocystic Breast Disease / Q000175:diagnosis; D049670:History, 17th Century; D006801:Humans