Case 6

Case of the Month 6

Clinical Summary
A 43-year-old female who had a history of invasive breast cancer with regional lymph node metastases one year ago presented with a rapidly enlarging mass in the posterior fossa at the cerebellopontine angle. The clinical impression and imaging studies were suspicious for metastases from the breast primary.

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This case was contributed
Dr. Hameed Aljawad, McMaster University
Dr. Monalisa Sur, McMaster University

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Image 1

Post contrast CT scan shows homogeneously contrast enhancing mass situated in the posterior fossa at the cerebellopontine angle.

Image 2

Frozen section showing cellular spindled and epithelioid cell neoplasm

Image 3

Frozen section showing a focus of necrosis

Image5

Paraffin section demonstrated epithelioid cells showing perivascular pseudo-rosette arrangement

Image 7

Electron microscopy demonstrated features characterestic for meningioma; and more important did not show features of epithelial or schwanomatous differentiation. are sheets of cells with broad cell processes, abundant cytoplasmic intermediate filaments, and (in inset) small junctions in between cells.

Image 4

Frozen section showing epithelioid cells with prominent nucleoli and a background of hemosedrin pigment

Image 6

The tumor cells were positive for epithelial membrane antigen (EMA)