Human Immunodeficiency Virus (HIV), Epstein Barr Virus (EBV), Hepatitis C Virus (HCV), Human T Leukemia Virus (HTLV), exposure to certain chemicals including pesticides, hair coloring agents, and herbicides e.g 2,4-dichlorophenoxyacetic acid (2,4-D) (Chiu and Blair, 2009). There are two main categories of lymphomas: Hodgkin (HL) and Non-Hodgkin lymphoma (NHL). Hodgkin lymphoma has been further divided into five subtypes on the basis of types of cells and their morphological arrangements (Alizadeh et al., 2000). Non-Hodgkin lymphomas are of B and T-cell types and further fall into categories on the basis of

Malignant melanoma has been considered as one of the most common tumor of the skin despite its occurrence in other organs. Being fatal in nature, timely detection and subsequent treatment is essential to avoid poor prognosis. The current case occurred in a 73-year-old male patient, with a melanoma presented as metastasis in parotid lymph node. The article discusses and focuses on the distinct clinic-pathologic presentation of this case, emphasizing the necessity to identify and report such cases for understanding of its molecular pathology role and impact. However, these rare lesions may present themselves in an un-common way which needs to be identified and reported to understand their biologic behavior. The current case report aims to fulfill the understanding criteria of such incidents.

Objective: To determine the frequency of mismatch repair deficiency in colorectal carcinoma determined by immunohistochemistry. Study Design: Cross-sectional study. Place and Duration of Study: Department of Histopathology, Armed Forces Institute of Pathology, Rawalpindi, from Aug 2018 to Jan 2019. Methodology: A total of 101 patients of adenocarcinoma of colorectum who underwent surgical resections and their characteristic and clinical data were recorded. Immunohistochemical stains were performed using antibodies MLH1, MSH2, PMS2 and MSH6. Results were interpreted and mismatch repair deficiency status of all patients was determined. Patients with loss of expression for MLH1, MSH2, PMS2 and MSH6 antibodies were observed and noted. Results: In this study, out of 101 patients with CRC, 71 (70.3%) were male and 30 (29.7%) female. The mean age was (54 years ± 15.9). Amongst the 101 cases loss of immunohistochemical staining for MMR proteins was noted in 19 patients (18.8%). The combined loss of all four antibodies was seen in one case, loss of MLH1 and PMS2 in 7, MSH2 and MSH6 in 5 and MLH1 only in 6 patients. However, no mismatch repair deficiency was detected in remaining 82 cases. According to statistical analysis no significant association between mismatch repair deficiency and variables was found. Conclusion: The frequency of mismatch repair deficiency in colorectal carcinoma patients was found to be 18.8% in our population.