A rare case of choroid plexus carcinoma that led to the diagnosis of Lynch syndrome (hereditary nonpolyposis colorectal cancer).

Lynch syndrome (hereditary nonpolyposis colorectal cancer) is an autosomal dominant disorder characterized by a significant risk of colorectal and endometrial cancers. A variety of other epithelial cancers may be associated with this syndrome. Brian tumors are infrequent, but have been reported in series. Here, we report a case of a 34-year-old Caucasian woman with WHO grade III choroid plexus carcinoma (CPC). Comprehensive genomic profiling of the patient's resected brain tumor revealed mutations in six genes: PTEN, VHL, MSH6, NOTCH1, RB1, and TP53. Family history is significant for endometrial cancer in her mother and sister as well as colon cancer in her maternal grandfather suggestive of Lynch syndrome. Site-specific mutational analysis showed the MSH6 mutation (p.R482*) in peripheral lymphocytes. Subsequently we performed immunohistochemical staining of the tumor tissue which demonstrated widespread loss of MSH6 with intact MSH2, MLH1, and PMS2. The diagnosis of Lynch syndrome due to a mutation in MSH6 was therefore established. Our patient elected to have adjuvant radiation to the surgical bed only followed by prophylactic total abdominal hysterectomy and bilateral salpingo-oophorectomy and is doing very well. To our knowledge, this is the first case report of CPC in an adult patient with a germline MSH6 mutation. We believe our data have provided molecular evidence to suggest that CPC could potentially be part of the Lynch syndrome spectrum.