29 June 2023
: Case report 
Endometrial Adenocarcinoma with Discordant Microsatellite Stability Status Treated with First-Line Pembrolizumab: A Case Report and Narrative Review
Unusual clinical course, Challenging differential diagnosis, Unusual or unexpected effect of treatment, Rare coexistence of disease or pathology
Christopher R. Grant1ABCDEF*, Elaine J. Chiao1EF, Zhaohui L. Arter2ADE, Cary Johnson3C, Truc Tran3BE, Farshid Dayyani2E, Krishnasu Tewari2E, Valery Vilchez4E, Joseph Carmichael
4E, May Cho2ABCDE
DOI: 10.12659/AJCR.939448
Am J Case Rep 2023; 24:e939448
Table 2. Case reports regarding discordance between primary and recurrent/metastatic carcinoma.
| Author [reference], year | Age, years/sex | Diagnosis | MSI status discordance | Previous treatment | Treatment | Response to immunotherapy |
|---|---|---|---|---|---|---|
| Zeng et al [], 202116 | 73/M | Esophageal squamous cell carcinoma | Primary lesion (MSS) and metastatic cervical spinal mass lesion (MSI-H) | Platinum-based therapy and radiotherapy | Pembrolizumab 100 mg every 3 weeks | Complete response for over 24 months |
| Chen et al [], 201615 | 64/M | Gastric adenocarcinoma | Primary gastric cancer (MSS) and recurrent gastric cancer (MSS) | Trastuzumab plus pertuzumab, cisplatin, and capecitabine | Pembrolizumab monotherapy (200 mg every 3 weeks) for 3 months | Partial response |
| Brasó-Maristany et al [], 202114 | 44/F | Breast carcinoma | Recurrent breast cancer (MSS) and axillary node (MSS) | Trastuzumab, radiation and hormonal therapy (unspecified) | Atezolizumab 1200 mg monotherapy every 3 weeks with weekly 100 mg/m nab-paclitaxel | Partial response through 24 months |
| Keithireddy et al [], 202213 | 56/F | Gastric adenocarcinoma | Gastric adenocarcinoma IHC (MSI-H) and NGS (MSI-H), axillary LN (MSI-H) | FOLFOX | Pembrolizumab | No response |