Expression of neuro-oncological ventral antigen-1 in small-cell lung cancer and its value in pathological diagnosis

Small-cell lung cancer (SCLC) was first reported by WHO in 1926 (1) as a poorly differentiated malignant tumour that is highly proliferative, invasive, metastatic and sensitive to chemotherapeutic drugs but tended to develop drug resistance (2). In 2012, 353,000 people died of lung cancer in Europe (3); SCLC accounted for 10–13% of these deaths, and smoking was a major risk factor. SCLC originates from K cells of the bronchial epithelial mucous gland, which fulfil a neuroendocrine function, and its pathological types include the oat cell, intermediate and mixed types. Under the microscope, tumour cells are spindle-shaped or lymphocyte-like, with few cytoplasm and coarse particles. The cells are often densely integrated into groups, some arranged like parallel fences and shaped like oats. In clinical practice, the characteristic arrangement and cell shape may be destroyed due to squeezing during sampling, which makes HE sections of SCLC hardly distinguishable from lymphocyte infiltration, poorly differentiated squamous cell carcinoma (SCC), basal cell carcinoma, etc., especially when the sample is taken by fiberoptic bronchoscopy or lung biopsy, which result in a sample with fewer cancer cells. In such situations, it would be extremely important to make full use of immunohistochemical indicators for differential diagnosis. Currently, commonly used markers for SCLC include CD56, Syn and CgA. Compared to Syn and CgA, CD56 is more sensitive to SCLC, but it is also expressed in natural killer cells (NK cells), SCC, adenocarcinoma, mesothelioma, etc., so its specificity is relatively low. Most SCLCs express neuroendocrine markers; nevertheless, up to 10% of SCLC cases are negative for all three neuroendocrine markers (4). In addition, commonly used SCC markers P63, P40, etc., can be expressed in SCLCs, making its diagnosis more difficult. So, it is necessary to find a novel neuroendocrine marker with higher specificity and sensitivity for the diagnosis of SCLCs