Miliary brain metastases from primary gastric small cell carcinoma: illustrating the seed and soil hypothesis.

Miliary metastases are a very rare condition usually found in the context of primary lung tumor (small cell and adenocarcinoma), and refer to the existence of numerous tumor nodules in widespread areas of the brain. Besides pulmonary neoplasia, pancreatic adenocarcinoma and malignant melanoma have also been implicated in some cases of miliary metastases. We present the first case of miliary metastases originating in a primary small cell gastric carcinoma (PSCGC), a rare type of neuroendocrine gastric tumor. This location should therefore be investigated whenever other more frequent tumors have been excluded as a cause for this particular type of metastases. The pathological resemblance of PSCGC with small cell lung carcinoma may correspond to an underlying similarity in biological behavior, which accounts for this particular pattern of metastatic spreading, as proposed in the seed and soil hypothesis.