Pathological and histological study on retinoblastoma.

We studied 30 cases of retinoblastoma (Rb) pathologically and histochemically. Rb cases were classified into two types, 18 cases of differentiated (D-type) and 12 undifferentiated type (U-type) according to International Classification of Diseases for Oncology(1990, WHO). D-type of Rb is found more commonly in younger infants less than 1 year, but U-type found more frequently in aged infants from 2 to 4 years. D-type Rb showed more marked necrotic areas, degeneration and calcification. Immunohistochemical stains were carried out in 21 cases of Rb by use of MIB-1, PCNA, bcl-2, Fas, BAX, NF, SP and Tunel stains, respectively. MIB-1 is a good marker of proliferation of Rb cells and its high positivity correlates closely to more extensive necrotic areas of Rb cases. There are only a few positive cells by Tunel stain suggesting apoptotic cells, but diffuse positive cells by bcl-2 and Fas and completely negative by BAX gene. From these results, it can be seen that differentiation of Rb cells may be affected by bcl-2 and Fas but not by BAX gene.