What is the most likely diagnosis and differentials?
This patient has a known history of breast cancer, which makes metastasis the most likely diagnosis. We should bear in mind that metastases are the most common intracranial tumour in adults, and a known primary cancer elsewhere will support this hypothesis. Infection (abscess) could also be a possibility, but no other clinical data tends to support this diagnosis. Haemangioblastoma is a cystic tumour that occurs in the cerebellum in elderly patients, but usually, their cyst walls do not enhance. Otherwise, the presence of a second small supratentorial lesion favours metastasis against the other neoplastic possibilities.
An irregular multicystic mass with peripheral nodular enhancement is demonstrated within the superomedial left cerebellar hemisphere. No hydrocephalus. A solid enhancing left frontal parafalcine nodule is also observed (meningioma?) and small nodule is noted in the left frontal corona radiata.