Gonadotropin and alkaline phosphatase producing occult gastric carcinoma with widespread metastasis of generalized bone.

A case is reported of a small primary occult gastric adenocarcinoma occurring in a 57-year-old man revealing widespread metastasis to generalized bone, and associated with high serum level of circulating human chorionic gonadotropin (hCG), carcinoembryonic antigen (CEA), and alkaline phosphatase (ALPase). The primary site of metastatic bone tumor was not clear until autopsy. Microscopic examination of the gastric primary revealed moderately differentiated tubular adenocarcinoma admixed with numerous signet-ring carcinoma cells without conspicuous trophoblastic differentiation. The elaboration of hCG and intestinal and placental isoenzyme of ALPase by carcinoma cells themselves was confirmed by the indirect immunoperoxidase method. The present case may be interesting because of unusual metastasis and simultaneous production of hCG, CEA, and intestinal and placental ALPase isoenzymes.