A 53 year- with a subacute onset of ataxia and dysarthria, which had lasted for ca 4 weeks, was hospitalised in our department. She also described having double vision for a brief period, however this had been resolved at time of admission. The neurological examination showed an alert and oriented patient with severe trunk ataxia, dysarthria, horizontal nystagmus, dysmetria and intention tremor. The patient's medical history was unremarkable except for a previous Hashimoto thyroiditis. Brain MRI showed a meningeal cerebellar intensive contrast enhancement, associated with micro nodulations of the cerebellar hemisphere cortex (Fig. 1). Initially, the findings were concerning due to the possibility of a neoplastic process, such as a brain carcinomatosis in the structures of posterior cranial fossa versus an inflammatory cerebellitis. However, cerebral spinal fluid (CSF) analysis on two different samples performed two weeks apart did not reveal malignant cells. On the contrary, some inflammatory changes were detected on the first CSF analysis: mild pleocytosis (21 cells/mmc), high proteins (73 mg/dl) and oligoclonal bands. We looked for and found anti-Yo antibodies in the serum, fulfilling the diagnostic criteria for definite Paraneoplastic Neurological Syndrome (PNS) . A body CT scan was then performed, without detecting a clear primitive cancer. Mammography was not done as the patient could not stand; however her breast ultrasound was unremarkable. Intravaginal ultrasound study revealed an intramural uterine nodule and a left ovarian structural alteration. There was a mild increase of CA-125 oncomarker. The patient underwent treatment with a high dose of intravenous steroids (methylprednisolone 1 gr for 5 days), without clinical changes, followed by intravenous IgG treatment (0,4 gr/kg in 5 days) obtaining a slight improvement of symptoms. A Brain MRI, performed 10 days after the latter treatment, also showed a positive evolution. Indeed, no cerebellar contrast enhancement lesions were present, whereas a mild cerebellar atrophy was noticed (Fig. 1). In order to continue the research of the underlying tumor, we performed an 18-FDG PET/CT, showing a single spot hypermetabolism in the right inguinal region. A lymph node was then detected and removed. The histological examination revealed an undifferentiated cancer of possible ovarian origin based on immunohistochemical analysis (Fig. 2). The patient was advised to have a surgical treatment of ovariectomy with the intention of achieving maximum recovery of the neurological syndrome. Unfortunately she refused the surgery and her neurological condition was unchanged 6 months after the onset.