The Ultrastructural Study of Intermediate Filaments in Epithelial and Mesenchymal Tumors

Suh, Chae Hong; Kee, Keun Hong

Abstract

The immunohistochemical results are compared with ultrastructural features of neoplastic epithelial cells and mesenchymal cells to assess whether immunohistochemistry is useful in the differential diagnosis of epithelial tumors and mesenchymal tumors. Squamous cell carcinoma and transitional cell carcinoma exhibited positive reaction for keratin, but adenocarcinoma was weakly positive reaction for keratin. Ultrastructurally, heavy bundles of tonofilaments were more frequently encountered in squamous cell carcinoma. In adenocarcinomas, the intermediate filaments were arranged randomly as nonaggregated, short filaments spread throughout the cytoplasm. Fibroblastic and fibrohistiocytic tumors, schwannomas, and neurofibromas exhibited positive reaction for vimentin and alpha-smooth muscle actin. Vimentin consisted of large aggregates of gently curved filaments that often displace other cytoplasmic constituents was noted. Fibroblastic cells with features of smooth muscle differentiation were found in granulation tissue of healing wounds, hypertrophic scars, fibromatosis, fibroma, neurofibroma and malignant fibrous histiocytoma. Smooth muscle tumors showed abundant bundles of thin filaments with dense bodies, pinocytotic vesicles and dense attachment plaques along the cell membrane. Skeletal muscle tumors showed bundles of disorganized thick and thin filaments, remnants of sarcomeres and Z-bands. From the above result, ultrastructural and immunohistochemical studies on epithelial and mesenchymal tumors were useful in tumor diagnosis sand classification.