Distribution of histaminase in human tumor tissues. An immunohistochemical study

Tissue samples from 125 cases of a variety of human malignancies and benign conditions were examined for the presence of histaminase by the immunoperoxidase method on conventional pathological specimens. Histaminase was found diffusely in the cytoplasm of cancer cells of primary and metastatic tumors of lung, thyroid gland, pancreas, stomach, esophagus, ovary and pharynx. Histaminase-positive cases were also found in carcinoids, dysgerminomas and in melanoma. The incidence of positive histaminase staining in epithelial malignancies overall was 28/84, and those in sarcoma as well as in benign conditions were 1/22 and 0/19, respectively, excluding placental decidual cells and eosinophils intermingled in the tissues. No significant difference in the incidence of histaminase was found by histological type or by degree of cellular differentiation. The present results thus provided another direct evidence for the production of histaminase by many kinds of tumor cells.