2022 Volume 71 Issue 1 Pages 10-19
The appropriate storage of histopathological specimens is important for continuous patient care in various fields such as carcinoma genomic medicine. Usually, block surfaces after sectioning are thinly coated with paraffin for protection against damage and oxidation. However, some tissues are lost during cutting with repeated use of stored tissue blocks. In this study, we attempted to overcome this problem by using hydrosoluble paraffin. The specimens used were multiple control tissues and tissues from the tonsil and lung. In this investigation, we compared among specimens with hydrosoluble paraffin and conventional paraffin coating and without coating. Hydrosoluble paraffin was removed by washing with running water or immersion on an ice bath. The hydrosoluble paraffin protected tissues from cracking and oxidation. The time required to remove hydrosoluble paraffin was 5 min in running water and 30 min on an ice bath. HE-stained and immunostained specimens remained stable for six months. However, the attenuation of MIB-1 staining and decrease in DIN value occurred in tissue blocks stored for three years. The repeated use of tissue blocks induced tissue degeneration or water absorption, indicating the loss of the protective effect of hydrosoluble paraffin. Therefore, the use of a fresh reagent is important. Our novel method of covering tissue blocks using hydrosoluble paraffin is easy, and there is little tissue loss after a rapid surface cutting and repeated use of tissue blocks. In conclusion, the new tissue protection method is useful especially for very small specimens such as needle biopsy specimens.
