This patient had a known history of lung carcinoma. He went on to have a craniotomy and excision of this cerebellar mass.
MICROSCOPIC DESCRIPTION: The sections show features of metastatic small cell carcinoma infiltrating into the cerebellar parenchyma. The tumour forms diffuse sheets. Thick cuffs of tumour surround blood vessels. The tumour cells have high N/C ratio with enlarged hyperchromatic nuclei, nuclear moulding, granular chromatin, inconspicuous nucleoli and scanty cytoplasm. Scattered mitoses and apoptotic bodies are present. Lymphovascular invasion is not seen. The tumour cells are CAM5.2, CD56, synaptophysin and TTF-1 positive.
FINAL DIAGNOSIS: Metastatic small cell carcinoma from the lung
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