Microsatellite instability in young patients with mucinous colorectal cancers – characterization using molecular testing, immunohistochemistry, and histological features

CONTEXT: The incidence of colorectal cancers (CRCs) in young Indian patients is higher than the international average. CRCs in young patients are commonly of mucinous type and show microsatellite instability (MSI). AIMS: To ascertain the MSI status of mucinous CRCs in patients ≤40 years of age by molecular testing and to correlate this with immunohistochemical (IHC) analysis and tumor histology. SUBJECTS AND METHODS: Archived formalin-fixed paraffin embedded tissue blocks of 30 young mucinous CRC patients were retrieved. MSI testing was done using two mononucleotide markers – BAT26 and NR24. IHC analysis was done using MLH1, MSH2, and MSH6. Histological features of all cases were studied. Data were analyzed using the SPSS software and the Pearson's chi-square test and Fisher's exact test. RESULTS: Eight out of 30 cases (26.7%) showed MSI by molecular testing. IHC identified seven of these cases. Histological features showing a statistically significant association with MSI were the presence of a well-differentiated adenocarcinoma component (P = 0.003), peritumoral lymphocytes (P = 0.002) and tumor budding (P = 0.021). CONCLUSION: The detection of defective mismatch repair (MMR) proteins using IHC for MLH1, MSH2, and MSH6 and molecular testing using BAT26 and NR24 appears to be a good protocol to detect CRCs with MSI. Histology could be useful in identifying cases that require screening for presence of MMR protein defects

Concerns with regard to an article

We have read with interest and concern the article titled “Consultations on human infection studies in India: Do people’s voices really count” by Sandhya Srinivasan and Veena Johari. The article expresses the opinions of 2 persons who have not visited CMC, nor have spoken to anyone concerned, to ascertain the authenticity of the information published or with regard to the purported research in CMC

Clofazimine induced enteropathy--a case highlighting the importance of drug induced disease in differential diagnosis.

A patient on treatment for multibacillary leprosy for the past three years, presented with episodes of abdominal pain. Since the patient improved with conservative management, clofazimine induced enteropathy was considered as a remote possibility. A review of the mucosal biopsies showed macrophages with crystal-storing spaces consistent with clofazimine deposition in the duodenum. This case highlights the need to consider and investigate drug-induced disease as part of the differential diagnosis.