Parasagittal Meningioma in a Middle-aged Female Harbouring Metastatic Ductal Carcinoma: A Rare Case of Incidentally Detected Tumour-to-tumour Metastasis

Abstract

Metastasis of a tumour particularly coming from breast into an intracranial meningioma is a rare phenomenon. Several factors related to tumour microenvironment have been suggested in the pathophysiology of these lesions, particularly the rich vascular network of meningiomas, expression of common hormonal receptors like Oestrogen Receptor (ER) and Progesterone Receptor (PR), local immunosuppression, and presence of cell adhesion molecules. Here, we present a clinicoradiologically unsuspecting case of intracranial, parasagittal meningioma who was operated for relief of symptoms of mass effect and was incidentally detected with tumour metastasis within the meningioma. A 50-year-old female presented with seizures, headache and visual disturbances since last one month. Radiology revealed a parasagittal mass which was likely to be meningioma. The patient was operated. On histopathology, a low-grade meningioma was seen with areas of metastatic adenocarcinoma. The metastatic foci were surrounded by fibroblastic meningioma cells. On Immunohistochemistry (IHC), the metastatic tumour cells were strongly positive for PR and Cytokeratin 7 (CK7) and a diagnosis of fibroblastic meningioma with intratumoural metastasis of ductal carcinoma was rendered. The patient was given radiotherapy for brain tumour and also started on chemotherapy for breast carcinoma with brain metastasis. Since the entity of “Tumour-to-tumour Metastasis (TTM)” is uncommonly thought of and its detection is not easy, it is important that both clinicians and pathologists should adequately examine tissue samples of excised meningioma, as detecting the presence of any metastatic foci within the main mass will alter the prognosis and treatment plan considerably.