Primary intramucosal synovial sarcoma of the sigmoid colon in a patient with a germline mutation in the MSH2 gene: A case report

Special features of sarcomas developed in patients with Lynch syndrome: a systematic review

Lynch syndrome (LS) is a genetic predisposition leading to colorectal and non-colorectal tumors such as endometrial, upper urinary tract, small intestine, ovarian, gastric, biliary duct cancers and glioblastoma. Though not classically associated with LS, growing literature suggests that sarcomas might develop in patients with LS. This systematic review of literature identified 44 studies (N=95) of LS patients who developed sarcomas. It seems that most sarcomas developed in patients with a germline mutation of MSH2 (57%) exhibit a dMMR (81%) or MSI (77%) phenotype, as in other LS-tumors. Although undifferentiated pleomorphic sarcoma (UPS), leiomyosarcoma, and liposarcoma remain the most represented histologic subtype, a higher proportion of rhabdomyosarcoma (10%, especially pleomorphic rhabdomyosarcoma) is reported. Further studies are required to better characterize this sub-population.

Case report: Undifferentiated sarcoma with multiple tumors involved in Lynch syndrome: Unexpected favorable outcome to sintilimab combined with chemotherapy

Background

Patients with Lynch syndrome are at an increased risk of developing simultaneous or metachronous tumors, while sarcomas have been occasionally reported. Sarcomas are generally not considered part of the common Lynch syndrome tumor spectrum. However, more and more studies and case reports suggested that sarcoma could be a rare clinical manifestation of Lynch syndrome, leading to new treatment strategies for sarcoma.

Case summary

We report the case of a 74-year-old male patient with Lynch syndrome who had rectal mucinous adenocarcinoma and prostate adenocarcinoma and then developed undifferentiated sarcoma of the left neck two years later. Mismatch repair deficiency (dMMR) was confirmed by immunohistochemical staining for the mismatch repair proteins MSH2, MSH6, MLH1 and PMS2. The result of polymerase chain reaction (PCR) microsatellite instability (MSI) testing of sarcoma showed high-level microsatellite instability (MSI-H). Additionally, a pathogenic germline mutation in MSH2 (c.2459-12A>G) was detected by next-generation sequencing (NGS). Taking into account HE morphology, immunohistochemical phenotype, MSI status, NGS result, medical history and germline MSH2 gene mutation, the pathological diagnosis of left neck biopsy tissue was Lynch syndrome related undifferentiated sarcoma with epithelioid morphology. The patient has been receiving immunotherapy (sintilimab) combined with chemotherapy (tegafur, gimeracil and oteracil potassium capsules) and currently has stable disease. We also reviewed the literature to understand the association between sarcoma and Lynch syndrome.

Conclusion

Sarcoma may now be considered a rare clinical manifestation of Lynch syndrome. Attention and awareness about the association between Lynch syndrome and sarcoma need to be increased. Therefore, timely detection of MMR proteins and validation at the gene level for suspicious patients are the keys to avoiding missed or delayed diagnosis and to identifying patients suited for immunotherapy, which may also help to provide appropriate genetic counseling and follow-up management for patients.

Clinicopathologic features of a patient with primary monophasic synovial sarcoma of the jejunum

A case of primary synovial sarcoma of the jejunum was collected and analyzed retrospectively. A 19-year-old man who presented to hospital with abdominal pain. The CT scan showed a large mixed abdominal mass with bleeding. Laparotomy revealed that the tumor originated from the jejunum, accompanied by rupture and hemorrhage. Microscopically, the tumor was composed of spindle cells. The tumor cells demonstrated diffuse expression of vimentin, transducin-like enhancer (TLE)-1, B-cell lymphoma protein (Bcl)-2, CD99 and focal expression of epithelial membrane antigen (EMA). The presence of specific SS18 gene rearrangement was confirmed in tumor cells. The patient received 6 cycles of chemotherapy after jejunal tumor resection. And 12 months later, the patient presented pancreatic metastasis and had radiotherapy. The patient died 15 months after the diagnosis.

Synovial sarcoma of the transverse colon metastatic to the chest wall after 3 years of follow-up

We report a fifth case of a transverse colon primary synovial sarcoma. A 31-year-old man with history of grade I obesity presented to an outpatient clinic reporting 6 months of intermittent colicky abdominal pain associated with haematochezia and rectal bleeding. Colonoscopy reported a partially obstructive intraluminal tumour lesion located in the transverse colon. There was no evidence of metastatic disease in the extension studies, so the patient was admitted to the hospital for a laparoscopic subtotal colectomy. Histopathology demonstrated intermediate-grade synovial sarcoma. At the third year of follow-up, the patient presented metastases on the chest wall, which required extensive resection and complementary oncological management.