Kanehito Morimoto

EXPERIMENTAL APPROACH TO FIBROUS HISTIOCYTOMA

A transplantable tumor was produced in syngeneic mice inoculated with transformed bone marrow macrophages (28–12– and L‐18 cell lines). The tumor composed of proliferative spindle cells was arranged in a storiform pattern, and was similar to that of human fibrous histiocytoma. Electron microscopically, the tumorous spindle cells had fibroblastic characteristics, while functionally, the tumor cells had histiocytic characteristics, and consisted of a transitional form between histiocytes and fibroblasts. We consider the spindle cells to be facultative fibroblasts. This Anding is compatible with the hypothesis that fibrous histiocytoma is derived from histiocytes.

OSTEOSARCOMA Ultrastructural and Immunohistochemical Studies on Alkaline Phosphatase‐positive Tumor Cells Constituting a Variety of Histologic Types

The osteosarcomas were subclassified into osteoblastic, fibroblastic, chondroblastic and telangiectatic types and examined by electron microscopy. Their immunohistochemical reactions were also studied. In an overall survey of the above types, fibroblast‐like cells revealed poorly developed cytoplasmic organelles with rather short, branching rough endoplasmic reticulum, mixed with osteoblast‐like cells that were hardly distinguishable from the former. They appeared to be an early stage of an osteoblastic cell lineage from the distribution and development of their cell organelles and highly positive vimentin activity. The tumor cells in malignant cartilage varied in appearance from chondroblast‐like to osteoblast‐like cells. All types of tumor cells expressed alkaline phosphatase activity to a significant degree. Immunohistochemical staining showed a mixture of procollagen type I‐positive cells among the cells positive for both procollagen type II and S‐100 protein in the malignant cartilage. Irrespective of any ultrastructural differences between these various tumor cell types, they all revealed a significant degree of ALPase activity unlike other types of bone tumors, suggesting that the tumor cells which constitute the various types of osteosarcoma are derived from a common precursor cell.

Intraosseous epidermal cyst of the sacrum. A case report.

An unusual case of intraosseous epidermal cyst is reported. The patient, a 45‐year‐old Japanese female, had suffered from lumbago and dysuria for about 15 years. X‐ray examinations and CT scan revealed an expanded osteolytic tumor without marginal sclerotic change within the sacrum, which anteriorly invaded the surrounding soft tissues at the S2/3 level. At this time, chordoma was suspected, but epidermal cyst with foreign body granuloma was finally diagnosed from biopsy and surgical specimens.

Longitudinal change in periprosthetic, peripheral, and axial bone mineral density after total hip arthroplasty

Abstract To determine the bone mineral changes after total hip arthroplasty, bone mineral densities (BMD) at the periprosthetic interface, lumbar spine, radius, and calcaneus were measured in a prospective and longitudinal observation. Twenty-four patients (24 joints) who had received a total hip arthroplasty and were followed longitudinally were enrolled in this study. The subjects comprised 2 men and 22 women with a mean age of 69.2 years at the time of surgery. Bone mineral measurements were performed at 1, 3, 6, 12, 18, 24, 30, and 36 months after surgery. The periprosthetic BMD after total hip arthroplasty continued to decrease for 6–12 months after surgery, and then recovered, except in Gruen zone 7 (the calcar region). The calcaneal BMD decreased rapidly for 3 months after surgery before increasing. The lumbar BMD showed a decreasing trend for 12 months after surgery, and then increased gradually. The radial BMD was not affected by surgery. We conclude that changes in the periprosthetic BMD after total hip arthroplasty show an apparent difference between zones, and also differ between the weight-bearing bones and the nonweight-bearing bones.