Synchronous appendiceal and intramucosal gastric signet ring cell carcinomas in an individual with CDH1-associated hereditary diffuse gastric carcinoma: a case report of a novel association and review of the literature

BACKGROUND: Hereditary diffuse gastric carcinoma is an autosomal dominant cancer syndrome associated with mutations of the E-cadherin gene (CDH1). E-cadherin is normally involved in cell-cell adhesion, so it not surprising that individuals with this syndrome are predisposed to develop malignancies with dyshesive morphologies at a young age, such as diffuse (signet ring cell) gastric carcinoma and lobular breast carcinoma. Herein we describe the first reported case of primary appendiceal signet ring cell carcinoma arising in a CDH1-associated hereditary diffuse gastric carcinoma kindred with synchronous primary diffuse gastric carcinoma. CASE PRESENTATION: A 51- year old woman, with known CDH1 mutation carrier status and a prior history of lobular breast carcinoma underwent prophylactic total gastrectomy which revealed multifocal intramucosal signet ring cell carcinoma. An appendectomy was performed at the same time due to a prior episode of presumed appendicitis, with pathologic examination significant for a primary signet ring cell carcinoma of the appendix. CONCLUSION: As appendiceal signet ring cell carcinoma is exceedingly rare, the occurrence of this neoplasm in this patient, with this particular morphology, provides credence for it being part of the hereditary diffuse gastric carcinoma spectrum of malignancies.