Acute Appendicitis with Neuronal Hyperplasia and Swelling: A Novel Histologic Mimic of Appendiceal Goblet Cell Adenocarcinoma and Signet-Ring Cell Adenocarcinoma.

Goblet cell adenocarcinoma and signet-ring cell adenocarcinoma are well-known diagnostic pitfalls of routine appendectomy specimens. Here we present a case of acute appendicitis with prominent neuronal (ganglion cell) hyperplasia and swelling which histologically mimics goblet cell adenocarcinoma and signet-ring cell adenocarcinoma. Attention to the cytologic features of the lesional cells (absence of atypia, mitotic activity) and their close association with nerves and classic ganglion cells, along with the use of a limited panel of immunostains, ensures proper classification of this rare but striking benign process.