Adenocarcinoid tumor of appendix presenting as unilateral Krukenberg tumor.

We report a case of adenocarcinoid tumor of the appendix that presented initially as a unilateral Krukenberg tumor (a signet ring cell mucinous adenocarcinoma with prominent cellular stroma). The primary tumor in the appendix was discovered 10 months later at the time of a "second look" laparotomy. The ovarian metastasis showed both goblet cell elements and tubular formations with numerous argyrophilic cells, indicating that both components of these tumors may metastasize, a finding at variance with the conclusions of some authors who suggest that only the mucinous component may metastasize. Theories of histogenesis of these tumors are discussed, and 12 previously reported cases presenting as Krukenberg tumors (all bilateral) are reviewed. Because the primary tumor in the appendix may be small and easily missed, appendectomy is recommended in all patients with Krukenberg tumors when another primary site cannot be identified at the time of surgery.