Objective: To find a morphological criterion of classification for choroidal invasion of retinoblastoma in order to further study clinical pathology of retinoblastoma (Rb) under an integrate rule.
Methods: The changes of retinal pigment epithelium, Bruch's membrane and choroid on histopathological sections of primarily enucleated eyes with Rb in 297 cases were observed under a light microscope.
Results: The globe wall invasion could be morphologically divided into four stages (briefly pigment epithelium-choroid classification). Stage I: Only retinal pigment epithelium was infiltrated, the Bruch's membrane was intact. Stage 2.: The Bruch's membrane was destructed, but the choriocapillaries were not invaded. Stage 3: The invasion reached middle choroidal blood vessels close to the choriocapillaris in a limited scope. Stage 4: Massive choroidal infiltration of all choroidal layers existed and the sclera could be simultaneously involved. The mortality for stage 4 was 11.5% and for stage 1 to 3 was 0.4%.
Conclusion: The pigment epithelium-choroid stage (PEC-stage) classification in our study can be used as an integrate rule to compare the invasion degree of retinoblastoma in different individuals and studies.