gastric signet ring cell carcinoma

Signet ring cell carcinoma and other poorly cohesive carcinomas are often composed of a mixture of signet ring cells and non-signet ring cells.

Poorly cohesive non-signet ring tumor cells are those that morphologically resemble histiocytes, lymphocytes, and plasma cells.

Those tumor cells can form irregular microtrebaculae or lace-like abortive glands, often accompanied by marked desmoplasia in the gastric wall and with a grossly depressed or ulcerated surface.

When it occurs at the antropyloric region with serosal involvement, the carcinoma tends to have lymphovascular invasion and lymph node metastasis.

Because signet ring cell and other poorly cohesive carcinomas at antroplyoric region have a propensity to invade duodenum via submucosal and subserosal routes including subserosal and submucosal lymphatic spaces, special attention needs to be paid to those routes when a distal margin frozen section is requested at the time of surgical resection.

Special stains such as cytokeratin immunohistochemistry can help detect morphologically occult signet ring cells in the lamina propria.

One important differential diagnosis of neoplastic signet ring cells in gastric mucosa is benign pseudo-signet ring cells which can remarkably mimic signet ring cell carcinoma.

Those pseudo-signet ring cells sometimes can demonstrate cytological atypia, even with mitoses.

However, those pseudo-signet ring cells do not reveal invasive pattern with reticulin stain which highlights pseudo-signet ring cells confined within basement membrane with intact acinar architecture.