Expression of B23/Nucleophosphamine Nonribosomal Nucleolar Protein in Smooth Muscle Tumors of the Corpus Uteri.

Immunohistochemical study of B23/nucleophosmine (NPM), the key argyrophilic nonribosomal protein associated with the nucleolus-producing regions, in smooth muscle formations of the body of the uterus and myometrium was carried out. The uterus index, number of positively stained nucleoli in the nucleus, integral optical density, and area of positively stained nucleoli were studied by computer-aided image analysis. The results indicated significant differences in the integral optical density and less so in the areas of NPM+ nucleoli in leiomyosarcomas, but not in intact myometrium and leiomyomas. Coefficients of variations in the integral optical density and NPM area proved to be significant parameters for differentiating leiomyosarcomas by size (≤7 cm or larger), evaluating the malignancy grade and stage of the process. NPM parameters in leiomyomas and leiomyosarcomas differed significantly, depending on the levels of Ki-67 and p53 expression and the receptor status of leiomyosarcoma. The index of area and the integral optical density of NPM could serve a accessory objective differential diagnostic criteria in cellular and mitotically active liomyomas and well-differentiated leiomyosarcoma of the corpus uteri.