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Adenomyoepithelioma of the breast: fine-needle sampling with histologic, immunohistologic, and electron microscopic
P Vielh1, J P Thiery, P Validire
1Laboratoire de Cytopathologie Clinique, Institut Curie, Paris, France.
Insights
A fine-needle aspiration diagnosed a benign breast tumor resembling sweat gland tumors. Histology confirmed a biphasic tumor with myoepithelial and glandular cells, supported by immunohistochemistry.
Area of Science:
- Pathology
- Cytopathology
- Surgical Pathology
Background:
- Fine-needle aspiration (FNA) is a key diagnostic tool for breast masses.
- Distinguishing benign from malignant breast lesions is crucial for patient management.
- Sweat gland-type tumors, though rare in the breast, present unique diagnostic challenges.
Observation:
- A subareolar breast mass in a woman was sampled using fine-needle aspiration.
- Cytologic examination revealed epithelial and spindle-shaped cells within a myxoid background.
- The initial cytologic diagnosis suggested a benign sweat gland-type tumor.
Findings:
- Histologic examination demonstrated a biphasic tumor architecture.
- The tumor comprised proliferating myoepithelial cells and glandular epithelial cells.
- Immunohistochemical and electron microscopic analyses confirmed the biphasic nature and cell types.
Implications:
- This case highlights the utility of FNA in diagnosing rare breast tumors.
- Accurate cytologic and histologic characterization is essential for benign tumor classification.
- Understanding the immunophenotype aids in differentiating tumor components and confirming diagnosis.
Abstract:
Fine-needle sampling was performed in a woman with a subareolar breast mass. The cytologic diagnosis was consistent with a benign sweat gland-type tumor. Cytologic features included epithelial cells and spindle-shaped cells lying free or in fibrillary myxoid ground substance. Histologic study revealed the biphasic appearance of this tumor composed of proliferating myoepithelial cells and glandular epithelial cells as supported by immunohistologic and electron microscopic analyses. Epithelial cells were strongly positive for cytokeratins, and spindle cells were positive for actin, S-100 protein, and keratin and showed ultrastructurally typical features of myoepithelial cells.
