The neurologic symptoms precede the detection of tumor ,based on staining pattern by immunohistochemistry, these antibodies may be classified as Anti-neuronal nuclear antibodies (ANNA): ANNA-1, ANNA­2, ANNA-3.Anti-Hu is an type IIa, ANNA (anti-neuronal nuclear antibody) type I antibody. Small cell lung carcinoma is found in more than 80% of patients with anti-Hu. The antibody is related with Clinical syndromes,such as Encephalomyelitis, limbic encephalitis, sensory neuronopathy, subacute cerebellar degeneration, autonomic neuropathy.Its associated tumors are SCLC, neuroblastoma, prostate.human IgG autoantibodies ANNA-1 and ANNA-2 provide novel tools for studying the cytogenesis of tumors of the nervous system in that they permit the identification of both normal and neoplastic, poorly differentiated and small neuronal cells that may escape detection using commercially available anti-neuronal antibodies.