Splenic metastases from mucinous neoplasms of the appendix and colon

Splenic metastases associated with mucinous intraabdominal tumors have been an enigma in the radiologic and oncology literature. These focal parenchymal defects from a non-metastasizing malignancy within an organ that rarely develops metastatic foci, even with high-grade cancer, were studied.

Information on 9 patients who underwent splenectomy with intraparenchymal splenic masses associated with appendiceal or colorectal mucinous tumors with peritoneal dissemination was collected. The CT scan, the histopathology and the clinical parameters of these patients were studied. A literature review searching for prior reports of this subject was performed.

Eight of these patients had mucinous appendiceal tumors and 1 a mucinous sigmoid colon cancer. All patients had mucinous carcinomatosis at some time in their clinical course. These splenic tumor masses had a CT image compatible with metastases and not compatible with mucinous tumor layered out of the splenic capsule. None of the patients had evidence of metastases to other sites such as liver or lymph nodes. All patients had a mucinous histopathology. Splenectomy may be associated with prolonged survival.

From our review of the clinical information available on these 9 patients, these splenic lesions were thought to be an entrapment of mucinous tumor within splenic surface trabeculae, which expand into the splenic parenchyma resembling metastatic disease. These CT findings may be more accurately referred to as splenic pseudometastases.