Expression of inducible nitric oxide synthase in carcinomas and sarcomas affecting the oral cavity

Context: Inducible nitric oxide synthase (iNOS) is a cytoplasmic enzyme which plays a crucial role in the pathogenesis of oral carcinomas and sarcomas. Aims: The objective of this study was to analyze the immunohistochemical expression of iNOS in carcinomas and sarcomas affecting the oral cavity in order to understand the possible role of iNOS in their biologic behavior and to correlate iNOS expression with lymph node metastasis in carcinomas and sarcomas. Settings and Design: Patients, who attended the oral diagnosis department of Vinayaka Missions Sankarachariyar Dental College, were screened, for the purpose of the study. Besides these, paraffin-embedded tissue blocks were also retrieved from archives of the Oral and Maxillofacial Pathology Department. A total of 40 cases (20 carcinomas and 20 sarcomas) were selected for the study. Subjects and Methods: A total of 40 cases (20 carcinomas and 20 sarcomas) were selected for the study. Five apparently normal tissues were obtained from the tumor adjacent normal tissue to be used as a control. These were subjected to immunohistochemical staining using antibody to iNOS and evaluated. Statistical Analysis Used: The results were analyzed using the Chi-square test. Results: Among the 20 carcinomas 19 showed a positive immunoreactivity for iNOS and 1 case was negative. Among the 19 immunopositive iNOS cases of carcinomas, 15 cases showed positive lymph node metastasis. Among the sarcomas, positive immunoreactivity for iNOS was seen in 10 hard tissue sarcomas, while the remaining 10 soft tissue sarcomas were negative for iNOS expression. The results were analyzed using the Chi-square test. Conclusions: iNOS is a reliable marker for lymph node metastasis in carcinomas irrespective of the histologic grade. The high expression in carcinomas shows that the carcinomas elaborate more angiogenesis for growth compared with the sarcomas with the exception of hard tissue sarcomas.