Anti-Zic4- and Anti-NMDAR-Positive Patients and Their Correlation with Clinical Course and Image Diagnostic Findings—Case Reports

Background/Objectives: Paraneoplastic Neurological Syndromes (PNSs) comprise a rare group of disorders present in various types of malignant neoplasia. In most cases, PNSs precede the clinical symptoms and diagnosis of a tumor by years. It is therefore vital to recognize these neurological disorders, as early diagnosis of the neoplasia offers the opportunity for timely initiation of treatment and may improve patient outcomes. Case Presentation: Panels of antineuronal antibodies (ANeAs) were used to examine serum and cerebrospinal fluid (CSF) samples from two PNS patients using indirect immunofluorescence assay (IIFA) and immunoblotting (IB). Both patients were anti-Zic4-positive. In addition, one patient was anti-Zic4- and anti-NMDAR-positive. The individuals also exhibited abnormalities on computed tomography (CT) and magnetic resonance imaging (MRI)—focal lesions suggestive of paraneoplastic cerebellar degeneration (PCD) and a tumor. During follow-up neuroimaging examinations, no tumor was found. Discussion: An in-depth study of a case series of PNS patients was carried out. Anti-Zic4 was correlated with PCD, whereas anti-NMDAR was correlated with autoimmune anti-NMDAR encephalitis. These case series may represent a possible non-paraneoplastic cerebellar syndrome associated with autoimmune encephalitis. Moreover, it is necessary for such individuals to undergo long-term follow-up in order to facilitate the early detection of a possible malignant neoplasia. Conclusions: In the current study, we focus on a case series of two patients with severely impaired neurological status, abnormalities in CT and MRI suggestive of PCD, and positive results for ANeAs—anti-Zic4 and anti-NMDAR. Through this study, we aim to emphasize the need for thorough clinical and laboratory follow-up of patients for eventual tumor development.