Nucleolar organiser regions in fibrous proliferations of childhood and infantile fibrosarcoma.

A silver colloid technique to identify nucleolar organiser region associated protein (AgNOR) was applied to 16 fibrous proliferations of childhood and six low grade fibrosarcomas. The fibrous proliferations comprised five cases of infantile digital fibromatosis, seven of infantile desmoid type fibromatosis, and four of infantile myofibromatosis. The AgNORs were visualised as dots within the nuclei of the cells, and on the basis of their relative mean numbers of AgNORs fibrous proliferations of childhood could be easily differentiated from low grade infantile fibrosarcoma. The differences observed were significant (0.01 greater than p greater than 0.001). This technique, previously the province of the cytogeneticist, may be of use to the pathologist in differentiating infantile fibrous proliferations.