A malignancy phantom: a rare clinical case report of metastatic renal cell carcinoma with no evidence of a primary lesion presenting as cerebellar ataxia

Abstract

Background: Anti-Ma2 antibody associated paraneoplastic syndrome (PNS) usually presents as limbic encephalitis in the context of testicular tumors. We report a rare case of anti-Ma2 positive PNS with deviation from the classic scenario, thus expanding the phenotype of anti-ma2 associated PNS. Case presentation: This is a 53-year-old male who presented with what was later diagnosed as anti-Ma2 antibody positive cerebellar ataxia. Further workup revealed retroperitoneal lymphadenopathy which, using biopsy, was identified as metastatic clear cell renal cell carcinoma (RCC). However, imaging did not reveal a primary renal lesion. Conclusion: Physicians should be aware of non-classic presentations of paraneoplastic syndromes, especially given that they commonly precede and point towards an underlying, many times undiagnosed, malignancy.