Claudin 18 immunohistochemistry for determining site of origin of metastatic neuroendocrine tumor

#3575

Introduction: Claudin 18 isoform 2 (CLDN18.2) is selectively expressed in normal and neoplastic gastric tissue and some pancreatic neoplasia. Anti-CLDN18.2 is an investigational therapy in gastric and pancreatic adenocarcinoma and a sensitive and specific immunohistochemical marker in these cancers.

Aim(s): We investigated the CLDN18.2 immunophenotypic profile in gastric well-differentiated neuroendocrine tumors (WDNETs) and its metastases compared with non-gastric NETs.

Materials and methods: We identified 3 gastric WDNETs in surgical pathology archives, one with liver metastasis and one with liver and lymph node metastases, and NETs of the pancreas (5), small bowel (6), and lung (5) with 1-2 paired metastases in all but two cases (total metastases, n=19). Each NET was stained with Ventana CLDN18 antibody (clone 43-14A). Membranous staining intensity (0-3+, none to strong) and extent (% of tumor cells) were assessed.

Conference:

Presenting Author: Smith B

Authors: Smith B, Rice K, Setthavongsack N, Woltjer R, Wong M,

Keywords: neuroendocrine, immunohistochemistry, claudin 18, CLDN18, gastric,