BREAST CYTOPATHOLOGY

80 3. Benign and Borderline Tumors
• Rarely epithelial fragments have an outer layer of
cells with clear vacuolated cytoplasm. However, epithelialmyoepithelial
distinction is rarely appreciated within the
same fragment.
• Background naked bipolar nuclei and metachromatic fibromyxoid
stroma are present (some resemblance to salivary
gland–type tumors).
• Stroma may have “collagenous spherulosislike” appearance.
• Rarely, apocrine cells and foamy macrophages are present.
• The tubular variant may show pseudopapillary cores with
cells arranged around branching vessels.
Pitfalls and Differential Diagnosis
• Biphasic breast tumors (fibroadenoma and others)
• Low-grade ductal carcinoma
• Mesenchymal neoplasms (of the spindle cell variant)
Figure 3.24. Adenomyoepithelioma. Loosely cohesive fragment of
ductal epithelium surrounding fibrous and myxomatous cores
characterize this lesion. (Smear, Papanicolaou.)