PTEN and P16 Expression Highlights Atypia and Malignant Transformation in Smooth Muscle Tumors of the Uterus
Mirka W Jones, Rohit Bhargava, David J Dabbs, Onisko Agnieszka, Giuliana Trucco. University of Pittsburgh, Pittsburgh, PA
Background: Tumor supressor genes prevent uncontrolled cell proliferation and provide genetic stability through regulation of cell cycle and promotion of apoptosis. Alteration of tumor supressor gene function either by deletion, mutation or an epigenetic event leads to tumor development. Immmunohistochemical expression of tumor suppressor genes can help in detection of malignant transformation in various tumors. We analyzed the differences in immunohistochemical expression of PTEN and p16 in 74 smooth muscle tumors of the uterus, including leiomyomas, atypical leiomyomas and leiomyosarcomas.
Design: 40 leiomyosarcomas, 12 atypical leiomyomas and 22 leiomyomas from the files of the Department of Pathology, Magee Womens Hospital of UPMC were reviewed and representative sections were immunostained with PTEN and p16 antibodies. Immunohistochemical staining was graded semi-quantitatively by considering the percentage and the intensity of the staining of tumor cells. The H score was obtained by applying the following criteria: H score = 1 X % of weakly (1+) staining cells + 2 X % of moderately (2+) staining cells + 3 X % of strongly (3+) staining cells. The H score ranged from 0 (no immunoreactivity) to 300 (highest immunoreactivity).