Dinucleotide microsatellite repeats are essential for the diagnosis of microsatellite instability in colorectal cancer in Asian patients

AIM: The molecular diagnosis of microsatellite instability (MSI) in colorectal cancer (CRC) is based on the analysis of five microsatellite markers. Among them, the two mononucleotide microsatellite repeats are considered more informative for this analysis than the three dinucleotide ones. The aim of this study is to establish the most relevant markers for MSI analysis in colorectal cancers from Asian patients. METHODS: The MSI analysis of 143 CRC cases in a routine molecular diagnostic laboratory was reviewed. Analysis by fluorescence-based PCR of the five recommended microsatellites was performed, followed by data interpretation according to internationally accepted guidelines. The results were analyzed to address (1) the rate of success in the analysis of histopathological samples not specifically preparedfor molecular analysis; (2) the relative importance ofindividual markers in the diagnosis of high-MSI (H-MSI).RESULTS: MSI analysis was unsuccessful in 34 cases (24%), but for tissues archived in recent years the unsuccessful rate was 5%. We found the D2S123 marker the mostvulnerable to inadequate tissue preservation, failing to amplify in 58 instances. Approximately 30% (32/109) of the cases were H-MSI, while 7/109 (6%) were low-MSI.A detailed analysis of the H-MSI cases revealed that the dinucleotide repeats (and D5S346 in particular) were more relevant than the mononucleotide repeats in assigning the correct MSI status. CONCLUSION: The analysis of dinucleotide repeats isessential for the establishment of MSI status in Asian CRC patients.

Locally Advanced Anaplastic Thyroid Carcinoma with Long-Term Survival of More Than 7 Years after Combined Surgery Including Tracheal Resection and Radiotherapy: Case Report

Background: Anaplastic thyroid carcinoma (ATC) is one of the most aggressive human malignancies with a mean survival time of 6 months regardless of treatment. Aim: To present a case of locally advanced anaplastic thyroid carcinoma with long-term survival. A 10-year literature review of locally advanced ATC with long-term survival (more than 2 years) is also presented. Case presentation: We present a case of locally advanced anaplastic thyroid carcinoma (ATC) with tracheal invasion in a 67-year-old elderly Chinese man who was treated with radical surgery encompassing total thyroidectomy, neck dissection and tracheal resection followed by adjuvant radiotherapy. Long-term disease-free survival is more than 7 years to date. Conclusion: The prognosis of ATC remains poor as it is characterized by aggressive and extensive disease at presentation, the inability in most patients to perform radical enough surgery in order to achieve clear margins, high morbidity of complete extirpation and limited response to radiotherapy or chemotherapy. However, if complete surgical resection is possible, patients should be treated aggressively with a combination of surgery and adjuvant radiotherapy.

Isolated gallbladder tuberculosis mimicking acute cholecystitis:A case report

BACKGROUND Isolated tuberculosis of the gallbladder is extremely rare due to its intrinsic resistance to tuberculous infections.There are reports of gallbladder tuberculosis mimicking cholecystitis or malignancy.However,these presentations were chronic.The diagnosis of gallbladder tuberculosis warrants the need for investigation of additional sites of inoculation and contact tracing of all tuberculosis contacts.Gallbladder tuberculosis is a rare entity but should be suspected in patients from endemic regions with risk factors such as underlying immunosuppression or history of tuberculosis.CASE SUMMARY We present a case of gallbladder tuberculosis presenting as acute cholecystitis.A 44-year-old Filipino lady presented with a 11-d history of right hypochondrium and epigastric pain which worsened after meals with no significant past medical history.She underwent laparoscopic cholecystectomy on the presumptive diagnosis of acute cholecystitis and diagnosed as gallbladder tuberculosis after histopathological examination.The patient did not have features of pulmonary or systemic tuberculosis nor was she immunocompromised.She recovered uneventfully.She was subsequently discharged and followed-up at a hospital in her home country due to financial and social reasons.CONCLUSION Clinicians should have a high index of suspicion for patients in endemic regions presenting with cholecystitis.