Progressive ataxic gait disorder.

Paraneoplastic cerebellar degeneration (PCD) is a well-described paraneoplastic syndrome. In patients with anti-Yo associated PCD, neurological symptoms precede the diagnosis of the underlying cancer in approximately 60% of cases. Ovarian, breast and other gynaecological malignancies are most frequently found as causative malignancies. Antitumour treatment should be commenced at an early stage of the disease. Identification of the tumour is a diagnostic challenge in many of these patients. In the case reported herein, a secondary tumour with unknown primary was suggested after detection of a pathological lymph node in the right axilla by a positron emission tomography scan. Microscopic examination of the ultrasound-guided resected tissue was a poorly differentiated adenocarcinoma strongly positive for the C-ERB 2 oncoprotein. A micro-invasive mammary carcinoma was unable to be localized, even with the aid of magnetic resonance mammography and axillary clearance. Intravenous gamma-globulin and steroid treatment and rehabilitation failed to influence the neurological symptoms. The present patient also demonstrated diffuse increase on the T2 signal in the cerebellum, which may provide a useful diagnostic clue in the assessment of PCD.