MICROSCOPIC DESCRIPTION: 1. The sections show features of meningioma. No metastatic tumour is seen. 2. The sections show features of metastatic moderately differentiated adenocarcinoma. The tumour forms many glandular structures. The tumour cells have enlarged nuclei, prominent nucleoli and moderate amounts of pale cytoplasm. In some areas, the tumour forms trabeculae and cords but the tumour cells are rather crushed. They seemingly have higher N/C ratio. No evidence of lymphovascular invasion is noted. The carcinoma is seen to invade into a meningioma. The meningioma forms whorls. The tumour cells have ovoid nuclei with no nuclear pleomorphism. Mitoses are inconspicuous. No brain invasion is seen. No evidence of atypical or malignant change is identified. The tumour cells from the carcinoma are CK7 and TTF-1 positive, in keeping with lung primary. All the glands and crushed areas are synaptophysin positive, indicating neuroendocrine differentiation. However, the morphology is not typical for large cell neuroendocrine carcinoma or small cell carcinoma. The tumour cells from the meningioma are diffusely progesterone receptor positive. The Ki-67 index is about 2%.
DIAGNOSIS: 1,2. Brain tissue: Metastatic moderately differentiated adenocarcinoma with neuroendocrine differentiation, in keeping with lung primary, invading into a grade I meningioma.