Patterns reported positive in five or less patientsincluding blood vessels, grey matter, white matter, neuropil, nucleus of neurons and synapses of neuronswere grouped into the minor patterns group for statistical reasons. patients were grouped according to (i) reported immunofluorescence pattern and (ii) established diagnosis, after which contingency table analyses were performed to investigate an interrelation between reported pattern and diagnostic group. Results In 3.7% of cases, patients with an atypical pattern obtained a final diagnosis of a paraneoplastic neurological syndrome. The presence of atypical patterns was more prominent in patients with epilepsy or peripheral neuropathies (IIF patterns on primate cerebellum such as positive neuronal nuclei (anti-Hu) or Polidocanol coarse granular staining of cytoplasm of Purkinje cells (anti-Yo) [1, 12, 13, 17]. However, atypical patterns that are not specifically related to a PN Ab (i.e. negative on typing for intraneuronal and anti-Amphiphysin Ab), are also reported. For example, the Purkinje cell layer can show positivity without a specific pattern (coarse granular staining of Purkinje cell cytoplasm) being reported, while in e.g. the molecular layer a pan-layer fluorescence instead of a specific pattern (e.g. dot-like fluorescence or positivity of neuronal nuclei) is often seen. The clinical significance of such patterns is not yet known. An overview of antineuronal antibodies with their associated fluorescence patterns, neoplasms and clinical features can be seen in Table?1. Open in a separate window Fig.?1 Location of antineuronal antibody targets. Antibodies directed against intracellular antigens (excluding anti-GAD antibodies) generate specific indirect immunofluorescence patterns on primate cerebellum. R, receptor. Illustration made with Lucidchart (http://www.lucidchart.com) Table?1 Fluorescence patterns, neoplasms and clinical features/syndromes of antineuronal antibodies antinuclear antibodies, central nervous system, granular layer, limbic encephalitis, Lambert-Eaton myasthenic syndrome, MillerCFisher syndrome, molecular layer, Purkinje cell, paraneoplastic cerebellar degeneration, purkinje cell layer, paraneoplastic encephalomyelitis, paraneoplastic encephalomyelitis with rigidity and myoclonus, peripheral nervous system, paraneoplastic sensory neuropathy,?receptor, small-cell lung cancer, StiffCPerson syndrome aAntibodies in italics generate specific patterns on IIF (i.e. patterns that allow to differentiate between antibodies present) bAnti-Hu and Anti-Ri generate similar patterns (fluorescence of neuronal nuclei) but anti-Ri only stains nuclei of the central nervous system According to our experience, Polidocanol an atypical IIF pattern is reported in about 90% of positive screening assays, not followed by a positive typing assay (line blot). Therefore, this retrospective study aimed to determine, in regard to PNS, the clinical significance of an IIF pattern in Polidocanol the absence of a positive line blot for specific pattern-generating group I Ab. Furthermore, we evaluated, if any, the association between atypical IIF patterns on cerebellar slices on the one hand and particular diseases on the other hand. Methods Compliance with ethical standards This retrospective study was approved by the local ethical committee of the University Hospitals of Leuven (file number S59935). Sample analysis Serum and/or cerebrospinal fluid (CSF) samples of patients suspected of having a PNS are routinely outsourced for screening and typing to an experienced partner laboratory in Luxembourg (Laboratoires KetterthillLLIP, Belvaux, Luxembourg). IIF screening was performed upon diluted serum samples (1:10) and undiluted CSF samples with the Nova Lite? Cerebellum kit (Inova diagnostics Inc., San Diego, USA), on cryostat frozen sections of primate cerebellum. Upon screening assay positivity, sample typing was performed by means of the EUROLINE Neuronal Antigen Profile 12? line blot assay (Euroimmun AG, Luebeck, Germany), which tests for Ab directed against the following antigens: Amphiphysin, CV2, Ma/Ta, Ri, Yo, Hu, recoverin, Sox1, titin, Zic4, GAD Mouse monoclonal to CK7 and Tr. Results were sent by post and manually introduced into the laboratory informatics system. Inclusion criteria and data retrieval To determine the clinical significance of an atypical IIF pattern in regard to Polidocanol PNS, patients included in this retrospective study had to meet three criteria: an atypical IIF screening pattern on primate cerebellar slices (i.e. not specifically related to a PN Ab, Table?1), a negative.