MICROSCOPIC DESCRIPTION: 1&2. Paraffin sections show a densely hypercellular tumour within brain parenchyma. Tumour cells have pleomorphic round and oval nuclei with an open chromatin pattern and a small amount of pale cytoplasm. These are arranged in irregularly shaped solid islands within an intensely vascular stroma. There is prominent palisading of tumour cells at the periphery of some of the islands. Frequent mitotic figures are identified and there are several foci of tumour necrosis.Tumour is sharply demarcated from adjacent gliotic and oedematous brain parenchyma.
Immunohistochemistry shows strong membrane staining in tumour cells for E-cadherin and strong cytoplasmic staining for EGFR, pancytokeratin AE1/AE3 and cytokeratin CK5&6. There is patchy moderate staining for CD56. No staining for synaptophysin is seen in tumour cells.
The features are of metastatic undifferentiated carcinoma consistent with an origin from breast.
DIAGNOSIS: 1&2. Left frontal brain tumour: Metastatic undifferentiated carcinoma consistent with an origin from breast.
- Oestrogen receptor negative (no staining)
- Progesterone receptor negative (no staining)
- HER-2 negative (+ cytoplasmic staining <10%)
- EGFR positive
- Ki-67 approximately 60%
SUPPLEMENTARY RREPORT: Further immunohistochemistry shows tumour cells are TTF-1 -ve, CEA -ve, Napsin A -ve, cytokeratin CK7+ and BerEp4+. This profile is inconsistent with an origin of tumour from lung and an origin from breast remains highly likely.