[A light and electron microscopic studies of müllerian adenofibroma of the uterus]

Müllerian adenofibroma composed of both histologically benign epithilia and benign mesenchyme is considered to be a rare entity of mixed müllerian tumor. A case of müllerian adenofibroma of the uterus was studied by light and electron microscopy. Light microscopically, the cleft-like glands lined by single-layered columnar or cuboidal epithelial cells were distributed in the proliferation of surrounding fibroblast-like mesenchymal cells. Mitotic figures of mesenchymal cells were less than 1--2 in 10 high power fields, and no nuclear atypia or heterologous elements were observed. Electron microscopically, the epithelial cells had well-developed mitochondria, r-ERs, tonofilaments in the cytoplasm, and short microbilli or cilia protruding into the lumen. In the mesenchyme, two types of cells were observed. One was spindle-shaped cells resembling fibroblasts, and the other was cells resembling immature smooth muscle cells. The histological and ultrastructural features of müllerian adenofibroma were felt to resemble those of müllerian adenosarcoma, which may pursue a clinically malignant course. These findings suggest that müllerian adenofibroma and adenosarcoma may be in the common spectrum of mixed müllerian tumor.