Role of Mismatch Repair Deficiency Status and Microsatellite Instability in Relation to the Expression of Immune Checkpoint Proteins in Colorectal Cancer.

Introduction Colorectal cancer (CRC) is the third most common cancer in the world among men and second among women worldwide. One of the major molecular pathways responsible for the development of colorectal cancer (CRC) is the microsatellite instability (MSI) pathway. During carcinogenesis, the tumor cells express programmed death ligand-1 (PD-L1), which reduces the immunogenicity leading to the escape of immune attack. Anti-PD-L1 interaction is an upcoming line of research for the treatment of colorectal carcinoma patients. Materials and methods The present study was an ambispective study where the mismatch repair deficiency status (MMR) and programmed death ligand-1 (PD-L1) expression were studied using immunohistochemistry and then later analyzed and compared with the clinicopathological parameters and MSI status in relation to the expression of programmed death ligand-1 (PD-L1) in neoplastic and immune cells in a total of 55 biopsy specimen. MMR expression was reported as retained or loss of nuclear staining, and PD-L1 expression was taken as positive with a cut-off of more than or equal to 5% membranous positivity in both tumor cells and immune cells. Results The analysis showed a significant correlation of microsatellite instability (MSI) status with two of the clinicopathological parameters, which were the site of the tumor (p-value<0.001) and M stage (p-value<0.001). PD-L1 expression in neoplastic cells showed no significant correlation with the clinicopathological parameters, whereas PD-L1 expression in immune cells showed a significant association with gender (p-value=0.043). Also, MSI status showed a significant association with PD-L1 expression in tumor cells (p-value <0.001).

Clinical spectrum of myasthenia gravis: An institute experience over 8 years from North East India.

Background: Myasthenia gravis (MG) is a neuromuscular junction disorder usually associated with a thymic lesion. Aims and Objective: To study the clinical, serological, and thymic pathology in patient of MG from this corner of the country. Material and Method: A retrospective study involving all myasthenia patients presenting to neurology and cardio-thoracic department from the year 2013 to 2020. The clinical findings, Osserman grade of severity, antibodies profile, computed scanning thorax findings and histopathology of the thymic lesion were noted and collected as data. Results: Thirty patients of MG were included with mean age of onset being 39.10 ± 15.77 years which included 22 females and eight males. Four patients had only ocular findings while 26 patients had generalized myasthenia with three patients of respiratory failure. Ach receptor antibodies were positive in 27 patients and negative in two patients. Anti-MUSK was positive in one out of five patients. Abnormal findings in CT thorax seen in 20 patients which included enlarged thymic gland in 11 patients, thymic hyperplasia in two patients, thymoma in four patients, and anterior mediastinal mass in three patients. Thymectomy was done in eighteen patients with thymoma as the most common histopathological findings seen in eight patients, follicular hyperplasia in five patients; other was thymic hyperplasia, thymic cyst, normal thymus gland, and features of sarcoidosis in one patient. Conclusion: MG is a treatable autoimmune disorder with a variety of clinical, radiological, and histopathological findings.