Tokichi Yumoto

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.

Ossifying fibromyxoid tumor of soft parts.

A histologically uncommon soft‐tissue tumor of the extremities and neck of a 54‐year old male is reported. The solid, bony‐hard tumors occurred at the inner region of the right thigh at 44 years of age with additional tumor formation at the posterior region of the same thigh, at the inner region of the right upper arm and at the neck during the following 10 years. All tumors were located in the deep muscle layer. The neck tumor directly invaded the fifth cervical vertebra and later the upper mediastinum. Histologically, all three tumors of the extremities contained mixed lobular growths of round to fusiform cells with myxoid matrix and an extensive bone formation. The tumor cells showed a small round nucleus and eosinophilic cytoplasm lacking cytoplasmic glycogen. The myxoid matrix was stained significantly by alcian blue and colloidal iron and was digested completely by pretreatment with hyaluronidase. Another major component was mature bone trabeculae showing a dense meshwork throughout the entire tumor with active bone formation toward the periphery. Positive immunostaining was obtained against anti‐vimentin and S‐100 protein antibodies. We suggest that this uncommon tumor can be tentatively distinguished as an ossifying fibromyxoid tumor of soft parts, (an entity defined by Enzinger et al.), differing from other previously described soft‐tissue tumors. Acta Pathol Jpn 41: 480–486, 1991.

Ultrastructural features of malignant fibrous histiocytoma of bone.

Five cases of malignant fibrous histiocytoma originating in the femur and tibia, sometimes with local recurrences, are reported. Histological and clinical characteristics of this lesion were similar to those in soft tissues with the same disease. The present histiocytomas were observed by electron microscopy and shown to consist of 5 types of neoplastic cells which were regarded as undifferentiated cells, histiocyte‐like cells, which were predominating, flbroblast‐like cells, multinucleated giant cells and xanthomatous cells. These findings led us to confirm the existence of malignant fibrous histiocytoma originating in bone as well as in soft tissues.

Giant cell tumor of bone

Three giant cell tumors of bone (2 benign and 1 malignant) were examined enzyme-histochemically, and a tissue culture study of the malignant case was performed. Multinucleated giant cells and mononuclear round cells had similar activities of ACPase and non-specific esterase with a diffuse strong reaction. ATPase and 5′-nucleotidase reactions were strongly positive in the cytoplasm of multinucleated giant cells, and were seen not only in the cytoplasm but also on the cell membrane of round cells. The proliferating spindle cells in the malignant case were faintly positive for ACPase and non-specific esterase and were less positive for ATPase and 5′-nucleotidase on the cell membrane. The multinucleated giant cells and mononuclear round cells resembled histiocytes in the activities of 4 hydrolytic enzymes, and the multinucleated giant cells had enzyme activities similar to those of osteoclasts from new-born rat skull. The malignant giant cell tumor and cells in its tissue culture showed ALPase activity preferentially on the cell membrane of the spindle cells, and rarely on round cells or multinucleated giant cells. ALPase was resistant to heat treatment and was found to be the type IV isoenzyme by diffusion electrophoresis. The origin of the giant cell tumor of bone and the significance of the ALPase activity are discussed.

Combined Choriocarcinoma and Adenocarcinoma of the Lung

Combined choriocarcinoma and adenocarcinoma in the lung of a 71‐year‐old Japanese male is reported. In the upper lobe of the right lung (S1+ 2), a choriocarcinoma coexisted with an adenocarcinoma, but distinct metastatic lesions were noticed separately in the lungs, kidney, bone marrow and lymph nodes. Although immunohistochemical examination revealed intensely positive reactivity with anti‐human chorionic gonadotropin (HCG) in trophoblastic cells, weak immunoreactivities were also observed in a few cells with anti‐human placental lactogen (HPL), anti‐pregnancy specific β glycoprotein (SPI), anti‐epithelial membrane antigen (EMA), anti‐carcinoembryonic antigen (CEA), anti cytokeratin (keratin) and KM‐93 (lung adenocarcinoma‐associated antibody). In the adenocarcinoma, the tumor cells were positively stained for CEA, EMA, keratin and KM‐93, but there were no positive reactivities for HCG, HPL and SPI. These findings suggest that primary choriocarcinoma of the lung may arise through dedifferentiation of adenocarcinoma.

Osteosarcoma with Prominent Epithelioid Features

Osteosarcoma in the metaphysis to epiphysis of the left femur of a 17 year old male is reported. The lesion appeared osteolytic with sclerotic foci on roentgenographs, accompanied by an extensive tumor shadow in the surrounding soft tissue. While 60% of the tumor was necrotic, histological examination of the remaining viable tissue revealed that it consisted almost entirely of a sheet of epithelioid cells, separated by thin, fibrovascular septa with an alveolar‐like pattern, suggestive of metastatic carcinoma. Only a few areas were characterized by malignant osteoid tissue intermingled with the above cells, showing significant positivity for bone‐specific alkaline phosphatase and 5 nucleotidase, thus permitting a diagnosis of osteosarcoma. Autopsy findings revealed that the metastatic foci were histologically similar to those of the primary tumor. Electron microscopy revealed poor development of cytoplasmic organelles, supporting possible derivation from an osteoblastic cell lineage at an early stage. Acta Pathol Jpn 39: 439 445, 1989.

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.

PRELYMPHOMATOUS AND LYMPHOMATOUS CHANGES SPLENOMEGALY OF NEW ZEALAND BLACK MICE

The incidence of splenomegaly was 39.6% in the nontreated group 41.0% in the treated group, not significantly different between both gr Thymic lymphoma group shared 27.6%, while the nonthymic lymphoma gr 67.9%, significantly different between both. Histological findings of sp megaly of the nonlymphoma groups were divided into the following types. 1) follicular form, 2) periarterial lymphatic sheath form, 3) red hematopoietic form, 4) marginal zone form, and 5) red pulp reticulosis Histology of the spleen in the lymphoma group resembled each form of of splenomegaly in the nonlymphoma group. Lymphoma based upon mune abnormality and specific to this kind of mouse in nonthymic lympl continuously takes place from prelymphomatous changes in the nonlympl group. Splenic origin and role of marginal zone of nonthymic lymphor murine lymphoma is discussed.

EXPERIMENTAL TUMORS OF MYXOID MALIGNANT FIBROUS HISTIOCYTOMA and HYALURONIC ACID PRODUCTION

Using B‐10 tumor cells originated from mouse peritoneal macrophages transformed by simian virus 40, we succeeded in producing tumors in an ascitic form similar to human myxoid malignant fibrous histiocytoma. The tumor cells possessed Fc and C3 receptors, immunophagocytic activity, and lysosomal enzymes. They showed pseudopodic extensions of the cytoplasm containing lysosomes. Therefore, they maintained the functional and morphological characteristics of macrophages. On cellulose acetate electrophoresis with or without enzymatic degradation, the ascitic fluid contained a single component of glycosaminoglycans; hyaluronic acid. Electron microscopy utilizing dia‐lyzed iron demonstrated electron‐dense reaction products on the cell surfaces. Thus, the histiocytic origin of malignant fibrous histiocytoma was suggested and possibility was expressed, concerning the histogenesis of myxoid malignant fibrous histiocytoma, that the transformed tumor cells could synthesize hyaluronic acid on the cell surface and release it into the stroma. ACTA PATHOL. JPN. 37:975–988, 1987.

FIBROUS HISTIOCYTOMA OF THE NASAL CAVITY AND MAXILLARY SINUS

Two cases of fibrous histiocytoma were presented; Case 1: a 46‐year‐old man with a tumor filling the left nasal cavity and maxillary sinus, and Case 2: an 80‐year‐old man with a tumor of the right maxillary sinus destroying its surrounding wall. Histologically, the former was dominated by storiform pattern and onion‐like structures, and the latter by osteoclast‐like multinucleated giant cells. After radical surgery, Case 1 was free of recurrence for more than one year, and Case 2 showed recurrence although still maintaining fairly good health. A total of 29 cases hitherto reported arising in the nasal, paranasal and nasopharyngeal regions were reviewed, pitfall of differential diagnoses was commented especially in our two cases, criteria of malignancy were discussed, and the necessity of repeated samplings was emphasized because of paucity and unfamiliarity of fibrous histiocytoma arising, in particular, from the upper respiratory tract.