Prevalence estimation of microsatellite instability in colorectal cancers using tissue microarray based methods – A tertiary care center experience

Aim: Microsatellite instability (MSI) pathway is known to be implicated in carcinogenesis of 15% colorectal carcinomas (CRC), including 2%–3% of cases of Lynch syndrome, as per western literature. MSI status has important prognostic and therapeutic implications. The prevalence of MSI in Indian CRC patients is unknown. We aimed to determine the prevalence by studying 231 consecutive unselected cases of CRC. Methods: Tissue microarrays using duplicate cores per case for 141 cases, and whole tissue sections for 90 cases, were used. Immunohistochemistry with four mismatch repair (MMR) markers – MLH1, MSH2, MSH6, and PMS2 was performed. Molecular analysis for MSI status was performed in 18 randomly selected cases. Correlation with various clinical and histopathological features was done using univariate and multivariate analysis. Results: Loss of MMR immunohistochemical (IHC) was seen in 53/231 cases, i.e. 22.94% (95% confidence interval 17.52%–28.36%). MLH1-PMS2 dual loss comprised 13.9%, MSH2-MSH6 7.4%, and isolated PMS2 loss in 1.73% of cases. Univariate analysis showed significant association with age (<60 years), right-sided tumor location, histologic type, high grade, the presence of severe intratumoral lymphocytic (ITL) and peri-tumoral lymphocytic response, and N0 nodal stage. On multivariate analysis, independent variables were age < 60 years, right-sided location, and severe ITL. Molecular testing for MSI corroborated with the IHC results. Conclusion: The study results show a slightly higher prevalence of MSI-H phenotype, compared to Western literature, stressing the need for more widespread testing for better clinical management and identification of possible hereditary colon cancer syndrome.

Fracture of the penis with urethral rupture.

We report a rare case of penile fracture with incomplete urethral rupture in a 25 years old male who sustained the injury during sexual intercourse. He presented with a tense haematoma on the ventral aspect of the penile shaft, associated with urethral bleeding. Per urethral catheterization was possible though it was painful. Exploration and repair of the penile fracture and urethra were performed within 16 hrs. The patient made an uneventful recovery with good erectile and voiding function. This case illustrates the value of early surgical repair of the fracture in order to prevent complications. The true incidence of penile fracture is not known even in the Western countries because it is under reported or hidden for social embracement and even it is reported to physicians it remains undiagnosed or mismanaged. Very rarely it is associated with urethral rupture.