Pulmonary adenocarcinoma with multiple intracranial metastases in two cats

Case series summary: This case series describes two cases of feline primary pulmonary adenocarcinoma presenting with multiple intracranial metastases. Both cats exhibited acute and severe neurological deterioration characterised by multifocal neurological signs, significant mass effect, herniation and obstructive hydrocephalus identified on MRI. Histopathological analysis confirmed pulmonary adenocarcinoma with extensive intracranial metastatic disease, a rare and poorly documented phenomenon in cats. Relevance and novel information: Intracranial metastatic disease from pulmonary adenocarcinoma is rare in cats, and detailed descriptions of MRI characteristics of multifocal cerebral metastases are scarce. This report provides novel insights by documenting the MRI appearance of numerous ring-enhancing intracranial lesions, severe perilesional oedema, mass effect and obstructive hydrocephalus secondary to pulmonary adenocarcinoma metastasis in two cats. Such findings highlight the aggressive clinical course and emphasise the importance of including metastatic pulmonary adenocarcinoma in the differential diagnoses for cats presenting with multifocal intracranial lesions, even in the absence of obvious respiratory signs.