Microscopic Description -- Solid Mass in the Right Breast


PATHOLOGIC FINDINGS:

FNA:
Alcohol-fixed, Papanicolaou stained smear preparations of the breast lesion showed rare, markedly atypical ductal epithelial cells. These cells had abundant eosinophilic cytoplasm and pleomorphic nuclei with prominent nucleoli, hyperchromasia, coarse nuclear chromatin, and mitotic activity consistent with a malignant cell population. Rare cells featured prominent intracytoplasmic vacuoles. FNA of the axillary mass showed malignant cells in syncytial groups and singly, characterized by abundant, granular cytoplasm and vesicular nuclei with a high nuclear to cytoplasmic ratio. Many multinucleated giant tumor cells were present in addition to lymphocytes and histiocytes. The supraclavicular aspirate showed rare malignant cells, identified on the cell block, with features similar to those described above.

Right breast, core biopsy:
The core biopsy showed cords and cohesive aggregates of tumor cells with abundant, variably granular, eosinophilic cytoplasm, round, centrally to eccentrically located nuclei, prominent nucleoli, and distinct cell margins. A few cells with bizarre multilobulated nuclei and large, multiple nucleoli were also present. A focal in-situ component of the tumor was characterized by a similar although monotonous cell population forming a solid, mosaic pattern.

Immunohistochemical studies:
Immunohistochemical stains, performed on the core biopsy, revealed cytoplasmic reactivity of the tumor cells for cytokeratin (AE1/3), gross cystic fluid protein (GCDFP-15), and nuclear staining with androgen receptor. The tumor cells were non-reactive for estrogen (ER) and progesterone receptors (PR).

Electron microscopy:
Ultrastructural analysis was performed on tissue retrieved from paraffin-embedded formalin-fixed tissue. Examination revealed tumor cells with fairly abundant mitochondria, many of which contained osmiophilic bodies. Multiple intracytoplasmic empty vesicles were present. Occasional intracytoplasmic lipid droplets were also noted.

FINAL DIAGNOSIS




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