ENZYME HISTOCHEMISTRY OF BONE AND SOFT TISSUE TUMORS.

Abstract

Thirty-eight malignant and 72 benign soft tissue tumors, and tumors and tumor-like lesions of bone including 40 malignant and 28 benign cases were examined enzyme histochemically in the light and electron microscopes.Bone lesions, such as osteosarcoma, fibrous dysplasia and bone cyst showed strong alkaline phosphatase activity. Alkaline phosphatase reaction, however, seemed to be not always useful for the differential diagnosis between malignant fibrous histiocytoma and osteosarcoma, because a few cases of malignant fibrous histiocytoma were also alkaline phosphatase positive. Alkaline phosphatase positive soft tissue tumors were very few in number. Host capillaries in tumor tissues often showed alkaline phosphatase activity, but hemangioma and angiosarcoma were all negative. Although a few cases of undifferentiated spindle cell sarcoma were strongly alkaline phosphatase positive, how to apply this positivity to the differential diagnosis of spindle cell sarcoma remains to be investigated.Detection of positivity in adenosine triphosphatase and 5' nucleotidase reactions is not always easy in the light microscope, because tumor tissues usually have background staining to some extent. Electron microscopy is very helpful for the detection of weakly positive cases. Adenosine triphosphatase or 5' nucleotidase positive bone and soft tissue tumors were much more in number and kind than alkaline phosphatase positive tumors. While leiomyoma, leiomyosarcoma, neurilemoma, cardiac myxoma, giant cell tumor of bone, fibrosarcoma, mesothelioma, neurofibroma, and non-ossifying fibroma were adenosine triphosphatase positive, 5' nucleotidase activity was mainly found in the cases of leiomyosarcoma, cardiac myxoma, malignant fibrous histiocytoma, chordoma, angiosarcoma, non-ossifying fibroma, epithelioid sarcoma and leiomyoblastoma. Difference of adenosine triphosphatase and 5' nucleotidase reaction was found among the histological types of osteosarcoma. Osteoblastic and chondroblastic types showed adenosine triphosphatase and 5' nucleotidase reactions, whereas the activities were almost not found in fibroblastic type. Further investigation seems to be necessary to solve the problem how to apply these diverse enzyme histochemical findings to the differential diagnosis of sarcomas.It seems that lysosomal enzymes are not so useful for differential diagnosis of bone and soft tissue tumors as the membrane associated enzymes. Some of the cases of malignant fibrous histiocytoma showed prominent activity of acid phosphatase, beta glucuronidase and alpha naphthyl acetate esterase. Multinuclear giant cells of giant cell tumor of bone and osteoclasts in a bone metastasis of carcinoma showed strong acid phosphatase activity, but they had almost no activities of beta glucuronidase, alpha naphthyl acetate esterase and naphthol ASD chloroacetate esterase. Lysosomal enzyme activities of the two giant cells are similar but are different from that of macrophages. Such inflammatory cells as mast cells and neutrophils were naphthol ASD chloroacetate esterase positive in addition to acid phosphatase, beta glucuronidase and alpha naphthyl acetate esterase. Naphthol ASD chloroacetate esterase histochemistry seems to be very useful for detection of mast cells in tumor tissues which cannot be recognized by HE section. We could not find any difference in the number of lysosomal enzyme positive inflammatory cells between benigh and malignant lesions of bone and soft tissues. Lysosomal enzyme activities in soft tissue tumor cells were slightly higher in malignant than in benign cases, whereas there was no difference of the activities between benign and malignant bone lesions.