BREAST CYTOPATHOLOGY

50 2. Non-neoplastic and Proliferative Lesions
Pitfalls and Differential Diagnosis
• Ductal carcinoma
• Atypical ductal hyperplasia
• Metastatic tumors (most commonly, lung adenocarcinoma)
• Fibroadenoma (This possibility is uncommonly raised
because of the often biphasic appearance in gynecomastia.
The usual source of the loose metachromatic material often
seen in Diff-Quik–stained smears of gynecomastia is the
myxomatous change often noted in the periductular location
of these lesions.)
• Male breast carcinoma (Because carcinoma of male breast
is exceedingly rare, it should always be ruled out first; this
is particularly critical because gynecomastia can harbor significant
epithelial atypia. One should have a much higher
threshold for a cancer diagnosis when dealing with male
breast aspirates. Male breast carcinoma, which is almost
always the ductal type, shows greater pleomorphism,
smaller tissue fragments, more single cells, and total lack
of myoepithelial cell nuclei [Figures 2.35 and 2.36].)
Figure 2.35. Ductal carcinoma in male breast. (Smear, Papanicolaou.)