Reticulin staining clarifies florid benign signet ring cell change with mitotic activity in a penetrating gastric ulcer.

Signet ring cell change is a benign process that can be mistaken for signet ring cell adenocarcinoma. Signet ring cell change remains confined within the basement membrane and lacks an infiltrative growth pattern. It typically lacks cellular atypia, nuclear hyperchromasia, prominent nucleoli, or mitotic activity. This study illustrates a case of signet ring cell change with mitotic activity in a background of Helicobacter pylori gastritis with a penetrating ulcer. The signet ring cell change shows normal E-cadherin expression, absence of p53 expression, and confinement within glands on reticulin staining. The intact gastric mucosa adjacent to the signet ring cells shows significant mitotic activity, which likely explains the mitoses within the signet ring cell change. Mitotic activity in signet ring cells should be interpreted in the context of adjacent mucosa and should not preclude the diagnosis of benign signet ring cell change. Reticulin staining of the involved glands is helpful for excluding the invasion of the lamina propria in signet ring cell change.