Splenic metastases – hematogenous disease or invasive peritoneal implants? Case reports of two patients

BACKGROUND: Metastases from gastrointestinal and gynecologic malignancy may occur through lymphatic channels, through venules of the cancer or into the peritoneal space. The metastatic process involves lymphatic, hematogenous or transcoelomic dissemination. METHODS: Two patients with splenic metastases are presented. Their clinical course is presented in an attempt to identify the route of cancer dissemination to the spleen. Lymphatic, hematogenous, or transcoelomic patterns of cancer dissemination are possible. Transcoelomic cancer dissemination into the peritoneal space results in peritoneal metastases. RESULTS: In a woman with ovarian cancer peritoneal metastases, a large lesion within the parenchyma of the spleen was described. This disease was present at multiple other sites as peritoneal metastases but no hematogenous or lymphatic metastases. A second patient with mucinous appendiceal neoplasm with peritoneal metastases was studied. Hematogenous metastases from this malignancy is extremely rare and lymphatic metastases were not present at the time of right colon resection. After studying these two patients, our hypothesis is that splenic metastases result from transcoelomic dissemination to the splenic hilum or splenic notches with progression of disease into the parenchyma of the spleen. CONCLUSIONS: When oncologists are considering aggressive local-regional treatments for peritoneal metastases important patient management decisions are influenced by the presence versus absence of hematogenous metastases. We suggest that the presence of splenic metastases does not indicate systemic (hematogenous) or lymphatic metastatic process but an extension of peritoneal metastases at the hilum of the spleen or within splenic notches deep into the parenchyma of the spleen.