Low power: Pap stain
Scattered large signet ring cells singly dispersed in a background of lymphocytes
Medium power: Pap stain
Large single signet ring cells with round/ indented nuclei, prominent nucleoli and intracytoplasmic mucin
High power: Pap stain
Large single signet ring cell with indented nucleus and intracytoplasmic mucin
High power: Pap stain
Cluster of signet ring cells with round/ indented nuclei, prominent nucleoli, and intracytoplasmic mucin
High power: Pap stain
Cluster of signet ring cells with round/ indented nuclei, prominent nucleoli, and intracytoplasmic mucin
Cell block: H&E stain
Cluster of signet ring cells with round/ indented nuclei, prominent nucleoli, and intracytoplasmic mucin
Features
• Gastric adenocarcinoma subdivided into two types:
– Intestinal type (cytologically identical to colonic adenocarcinoma)
– Gastric type (poorly differentiated or signet ring cell type
• Scantly cellular
• Single cells and small loosely cohesive clusters
• Cytoplasmic mucin
• May have pleomorphic cells
• Small uniform cells
• Signet ring morphology due to pushed away nucleus
• Nucleus pushed to one side by large single mucin vacuole
• Nucleus classically indented, may be round
• Chromatin fine
• May have prominent nucleoli
• Lymphocytes and plasma cells may be present
• Express cytokeratin, Cam5.2, CK8, CK18, CK7, CK19, CDX2 +/- , CEA +/-