During the years 1952 through June, 1977, 64 children with tumor of germ cell origin were seen at the Department of Pediatric Surgery, the University of Tokyo Hospital. There were 39 mature, 7 immature and 18 frankly malignant teratomas. Sixteen cases had histological features of endodermal sinus tumor in pure or mixed form, and all of the last eight patients showed elevated serum AFP concentrations ranging from 92,000 ng/ml to 952 ng/ml. Serum AFP concentration declined almost to zero ng/ml with a half life of about 4 days when surgical removal was complete, whereas AFP decreased only to 100–200 ng/ml with radiation therapy and chemotherapy alone. Serum concentrations of prealbumin, albumin, alpha‐1‐antitrypsin and transferrin were almost within normal ranges.
Two endodermal sinus tumors were studied by tissue culture, which demonstrated secretion of diastaseresistant PAS‐positive hyaline globules. PAS‐positive granule is one of the characteristic histologic features of endodermal sinus tumor with demonstrable AFP specific immunofluorescence.