Microsatellite instability (MSI) is present in 15–20% of primary colorectal cancers. MSI status is assessed to detect Lynch syndrome, guide adjuvant chemotherapy, determine prognosis, and use as a companion test for checkpoint blockade inhibitors. Traditionally, MSI status is determined by immunohistochemistry or molecular methods. The Idylla™ MSI Assay is a fully automated molecular method (including automated result interpretation), using seven novel MSI biomarkers (ACVR2A, BTBD7, DIDO1, MRE11, RYR3, SEC31A, SULF2) and not requiring matched normal tissue. In this real-world global study, 44 clinical centers performed Idylla™ testing on a total of 1301 archived colorectal cancer formalin-fixed, paraffin-embedded (FFPE) tissue sections and compared Idylla™ results against available results from routine diagnostic testing in those sites. MSI mutations detected with the Idylla™ MSI Assay were equally distributed over the seven biomarkers, and 84.48% of the MSI-high samples had ≥ 5 mutated biomarkers, while 98.25% of the microsatellite-stable samples had zero mutated biomarkers. The concordance level between the Idylla™ MSI Assay and immunohistochemistry was 96.39% (988/1025); 17/37 discordant samples were found to be concordant when a third method was used. Compared with routine molecular methods, the concordance level was 98.01% (789/805); third-method analysis found concordance for 8/16 discordant samples. The failure rate of the Idylla™ MSI Assay (0.23%; 3/1301) was lower than that of referenced immunohistochemistry (4.37%; 47/1075) or molecular assays (0.86%; 7/812). In conclusion, lower failure rates and high concordance levels were found between the Idylla™ MSI Assay and routine tests.

Objectives: To report the first case of Arthrographis kalrae keratitis complicated by endophthalmitis in the UK and to review the current literature. Methods: A case report with literature review. Results: A 65-year-old male patient, with a background of treated B-cell lymphoma and herpes simplex virus-related neurotrophic keratopathy, presented with a large infiltrative corneal ulcer in the right eye. The patient was immediately commenced on empirical antifungal treatment in view of the clinical suspicion of fungal keratitis (FK). The initial corneal scrape identified the organism as nonspecific “mold,” and the identity of A. kalrae was subsequently confirmed using matrix-assisted laser/desorption ionization-time of flight-mass spectrometry (MALDI-TOF-MS). During the clinical course, the patient received topical, intrastromal, intracameral, and systemic antifungal treatment, repeat therapeutic corneal cross-linking treatment, and three penetrating keratoplasties. Although a temporary improvement was achieved with therapeutic corneal cross-linking treatment, the FK progressed relentlessly and was ultimately complicated by an endophthalmitis despite maximum medical and surgical treatment, eventuating in an enucleation. Conclusions: A. kalrae keratitis is an exceptionally rare clinical entity that poses significant therapeutic challenges. MALDI-TOF-MS serves as a useful diagnostic technique in identifying this rare organism. Although the literature suggested that A. kalrae keratitis may sometimes be controlled with antifungal medical treatment alone, this approach was proven to be futile in our immunocompromised patient with pre-existing neurotrophic keratopathy, suggesting that early surgical intervention such as therapeutic keratoplasty may be required in these cases.