Detection of Microsatellite Instability in Colonoscopic Biopsies and Postal Urine Samples from Lynch Syndrome Cancer Patients Using a Multiplex PCR Assay.

Identification of mismatch repair (MMR)-deficient colorectal cancers (CRCs) is recommended for Lynch syndrome (LS) screening, and supports targeting of immune checkpoint inhibitors. Microsatellite instability (MSI) analysis is commonly used to test for MMR deficiency. Testing biopsies prior to tumour resection can inform surgical and therapeutic decisions, but can be limited by DNA quantity. MSI analysis of voided urine could also provide much needed surveillance for genitourinary tract cancers in LS. Here, we reconfigure an existing molecular inversion probe-based MSI and BRAF c.1799T > A assay to a multiplex PCR (mPCR) format, and demonstrate that it can sample >140 unique molecules per marker from <1 ng of DNA and classify CRCs with 96−100% sensitivity and specificity. We also show that it can detect increased MSI within individual and composite CRC biopsies from LS patients, and within preoperative urine cell free DNA (cfDNA) from two LS patients, one with an upper tract urothelial cancer, the other an undiagnosed endometrial cancer. Approximately 60−70% of the urine cfDNAs were tumour-derived. Our results suggest that mPCR sequence-based analysis of MSI and mutation hotspots in CRC biopsies could facilitate presurgery decision making, and could enable postal-based screening for urinary tract and endometrial tumours in LS patients.

Enteric Type Bartholin Gland Adenocarcinoma: An Unusual Variant of a Rare Neoplasm.

Vulval cancer is rare. With Bartholin gland carcinomas representing <5% of all vulval carcinomas they present both diagnostic and management challenges. There are a small number of cases in the literature describing Bartholin gland carcinomas with unusual histology which necessitates the need to explore the possibility of metastases from elsewhere. We present a case of a 55-yr-old woman presenting with a vulval lesion within the Bartholin gland. Morphology demonstrated enteric type adenocarcinoma and the immunohistochemistry profile was positive for CK7, CK20, CDX2, CEA, and CA19-9. There was no evidence of an alternative primary cancer and the tumor was excised with negative regional sentinel node assessment. Genotyping showed no detectable mutations in KRAS, BRAF or NRAS suggesting a possible future role for anti-EGFR therapy.