RETURNHistologic Pattern of Osteosarcomas and Tumor Cell Differentiation: Cytomorphologic Analysis of Three Transplantable Osteosarcomas
Hironobu Andachi and Haruhiko Yoshida*
Department of Pathology, Faculty of Medicine, Tottori University and *Department of Medical Technology, Tottori University, College of Medical Care Technology, Yonago 683, Japan
Three osteosarcomas (OSs) of osteoblastic, chondroblastic and malignant fibrous histiocytoma (MFH)-like OS were inoculated into nude mice and maintained individually in order to clarify the phenotypic characteristics of the tumor cells constituting each tumor. Specific alkaline phosphatase (ALPase) activity was examined histochemically to detect bone-forming cells an glycogen granules for cartilage-forming cells. Tumor cells were categorized into 4 types on the basis of the presence and/or absence of ALPase activity and glycogen granules by periodic acid-Schiff (PAS) staining: osteoblastic cells (ALPase+PAS–), which were the major component cells of osteoblastic OS, vacuolated cells (ALPase–PAS+) defined as chondroblastic cells, spindle-shaped cells (ALPase+PAS+), and anaplastic large cells (ALPase+PAS–). Chondroblastic OS consisted of chondroblastic cells in addition to spindle-shaped cells and osteoblastic cells. Following repeated transplantation, the area composed of anaplastic large cells increased gradually in proportion to the chondroblastic area. The above findings indicate that osteoblastic and chondroblastic tumor cells may be derived from ALPase+PAS+ spindle-shaped cells, and that they change into another cell line of cartilage-forming cells.
Key words: cell differentiation; neoplastic cartilage; osteosarcoma; transplantation