We report a case of a 65-year-old male who presented with insidious onset progressive length dependent sensory symptoms, ataxia and a significant weight loss over a six month period. He had posterior column sensory loss and bilateral cerebellar signs. The investigations including vitamin B12, immunoelectrophoresis , vasculitic screen and serologies for HIV, hepatitis B, hepatitis C, syphilis were unremarkable. The tumour markers (CEA, AFP, PSA and CA19-9) were within the normal range. The MRI of brain and spine revealed moderate cerebellar atrophy and subtle signal change within the thoracic cord (T4 to T12).CT chest, abdomen and pelvis failed to show any evidence of malignancy. The serum anti CV2 (CRMP-5) antineuronal antibodies were positive. All other onconeural antibodies were negative.This prompted further investigation with PET scan which revealed a FDG avid mass in the left lung apex consistent with malignancy.
Anti CV2 (CRMP-5) antibody has been associated with small cell lung cancer and thymoma [1, 2]. Clinically it may present with paraneoplastic encephalomyelitis, cerebellar degeneration, chorea, uveitis and /or peripheral neuropathy [1, 2]. Its presence should prompt a thorough investigation for underlying malignancy. PET scan is useful when other investigations are normal. An early diagnosis, as in our patient of a localized tumour, can lead to a more prompt and definitive treatment of the underlying malignancy.
References:
1) Gozzard P, Maddison P Which antibody and which cancer in which paraneoplastic syndromes? Pract Neurol 2010; 10: 260-270
2) Dalmau J, Rosenfeld MR. Paraneoplastic syndromes of the CNS. Lancet Neurol 2008; 7: 327-340