BREAST CYTOPATHOLOGY

Pitfalls and Differential Diagnosis
• Fibrocystic changes, papillomatosis
• Pseudoangiomatous stromal hyperplasia
• Inflammatory myofibroblastic tumor
Adenomyoepithelioma 79
Adenomyoepithelioma
Clinical Features
Adenomyoepithelioma is a rare breast tumor characterized
by a biphasic proliferation of epithelial and myoepithelial
cells. The tumor has a low malignant potential. Therefore,
an accurate FNA diagnosis is clinically important for patient
management. The tumor is well-known for its histologic
heterogeneity, which is reflected in an often diagnostically
difficult cytopathologic interpretation. Three subtypes have
been described according to their growth pattern and predominant
cell type: tubular, lobular, and spindle. Most cases
behave in a benign fashion but can recur locally if incompletely
excised. Close follow-up is always required even
after excision.
Cytomorphologic Characteristics
(Figure 3.24 to 3.28)
• Smears are moderate to hypercellular.
• Cohesive fragments of epithelial and myoepithelial cells
occur in varying proportions.
• Epithelial cells display cohesive sheets and rarely tubules
with uniform nuclei containing grooves.
• Myoepithelial cells have a variegated appearance with
spindle, epithelioid, clear cell, and plasmacytoid morphology.
They appear as cohesive fragments, single cells with
well-preserved clear and vacuolated “soap bubble” cytoplasm,
or as naked bipolar nuclei in the background. Occasional
intranuclear inclusions are seen.