Tissue and Histopathology Section maintains and manages a valuable database of pathological specimens related to Thorotrastosis.Thorotrast is an X-ray contrast agent that was widely used from the 1930s to the 1950s. When injected into the body, the radioactive substance thorium dioxide is deposited in the liver, bone marrow, and other organs over a long period of time, causing internal exposure. As a result, after a latent period of several decades, various cancers, including hepatic angiosarcoma and intrahepatic cholangiocarcinoma, are known to develop. This series of pathological conditions is called thorotrastosis, and is considered one of the most common iatrogenic internal radiation exposures in humans.

This database was compiled by Dr. Manabu Fukumoto (Radiological Pathology, Tohoku University) and others based on cases collected from across the country by research teams from the former Ministry of Education, and the former Ministry of Health and Welfare, The case records, autopsy records, pathological tissue blocks, slides, and other actual specimens were deposited and transferred to Nagasaki University by 2023. With 668 registered cases, this is considered to be the largest collection of Thorotrast disease specimens in Japan. Tissue and Histopathology Section is building a comprehensive research and analysis system for Thorotrast disease by creating a detailed database of clinical information such as age, sex, and disease onset status, radiophysical information such as the amount of Thorotrast injected and cumulative dose, and pathological information obtained from pathological tissue blocks.

In the future, we will attempt to elucidate the mechanisms of internal radiation exposure and carcinogenesis from multiple perspectives by reexamining and reclassifying pathological diagnoses, reevaluating doses at a more detailed level, extracting nucleic acids from preserved pathological tissue blocks, and conducting molecular-level analysis. Research using this database is expected to make a significant contribution to the long-term evaluation of the effects of internal radiation exposure and the safety management of iatrogenic radiation exposure.