Partially ulcerated gastric and esophageal mucosal fragments infiltrated by an invasive moderately differentiated adenocarcinoma. The tumor is composed of crowded, irregular, and angulated and cribriform glands exhibiting fused and back-to-back architecture with minimal intervening stroma. These neoplastic structures are set within a desmoplastic background and are lined by atypical epithelial cells demonstrating nuclear enlargement, hyperchromasia, pleomorphism, loss of polarity, and prominent nucleoli.
Immunostaining was done with appropriate positive and negative controls and revealed:
Mismatch Repair Proficient (pMMR), demonstrating a low probability of Microsatellite Instability-High (MSI-H) status per CAP guidelines.
Referred block for immunostaining of gastric mucosal biopsy diagnosed as adenocarcinoma elsewhere.
Paraffin block for immunostaining.
Esophagus and Stomach, Gastroesophageal Junction Biopsy & Immunostaining: