Stimulation of endosteal bone formation by systemic injections of recombinant basic fibroblast growth factor in rats.

In vivo effects of basic fibroblast growth factor (bFGF) on bone formation was examined in rats. Daily systemic injections of 100 micrograms/kg bFGF for 7 days caused a marked stimulation of endosteal bone formation in both cortical and secondary cancellous bone areas. Histological examinations revealed that the sequence of responses to the injections of bFGF consisted of three phases: an early increase in the number of preosteoblastic cells over the osteoblastic cell layer (days 1-3), recruitment of osteoblasts from preosteoblastic cells (days 3-5), and an increase in new bone formation (days 5-7). These histological changes in the endosteum correlated closely with histomorphometrical parameters of bone formation, and the endosteal mineral apposition rate was almost unaffected during the initial 4 days but was markedly enhanced after this period. Immunohistochemical examinations using antitransforming growth factor (TGF)-beta 1 antibody demonstrated that immunostaining of preosteoblastic cells for TGF-beta already increased 1 day after bFGF treatment. Distribution of TGF-beta in osteoblasts and bone matrices began to increase on day 3, and all the osteoblasts and new bone matrices were intensively immuno-stained on day 7. These results demonstrate that systemic injections of bFGF in rats stimulate endosteal bone formation, and that the stimulation of bone formation is preceded by an initial increase in preosteoblastic cells with later recruitment of osteoblasts from these cells. Because the distribution of TGF-beta in the endosteal cells is increased by bFGF, the effect of bFGF may at least in part be mediated by TGF-beta. However, the precise mechanism of action of bFGF on bone formation remains to be clarified.

CD138-positive and Kaposi's sarcoma-associated herpesvirus (KSHV)-negative B-cell lymphoma with serosal spreading of the body cavity and lymphadenopathy: an autopsy case.

CD138-positive and Kaposi's sarcoma-associated herpes virus (KSHV)-negative B cell lymphoma with serosal spreading of the body cavity and lymphadenopathy is presented. Our lymphoma cells showed pleomorphic morphology and a clonal immunoglobulin gene rearrangement. Immunophenotypically, they lacked B- and T-cell-associated antigens but expressed strong membranous CD138 antigen along the serosa. Although our case was not conventional primary effusion lymphoma (PEL) because of the absence of KSHV and the presence of lymphadenopathy, its unique phenotype and serosal spreading were consistent with those of PEL. Our case suggests that, irrespective of KSHV infection, some pleomorphic B cell lymphomas with membranous CD138 expression show a peculiar serosal spreading.

Malignant fibrous histiocytoma of the larynx.

Malignant fibrous histiocytoma of the upper respiratory tract is rare. We report a case of a glottic malignant fibrous histiocytoma in a 46-year-old man. Ultrastructural findings demonstrated that tumor cells were composed of fibroblast-like cells with abundant rough endoplasmic reticulum, histiocyte-like cells with numerous lysosomes and transitional cells with characteristics of both the fibroblast-like and histiocyte-like cells. Laryngeal microsurgery was performed as surgery and the patient has done well without recurrence to date (8 months after surgery).

Pigmented squamous cell carcinoma of the alveolar ridge in the oral mucosa.

The clinical and morphologic features of a pigmented squamous cell carcinoma of the alveolar ridge in an 81-year-old Japanese woman are reported. The tumor was typical, well-differentiated squamous cell carcinoma but had many melanin-containing cells within it. Electron microscopy showed melanosomes in macrophages, melanocytes, and neoplastic squamous cells. Those in the neoplastic squamous cells seemed to have been excreted from the cytoplasmic processes of melanocytes.

Malignant plasmacytoid myoepithelioma of the palate: histological observations compared to benign predominant plasmacytoid myoepithelial cells in pleomorphic adenoma of the palate.

Predominant benign plasmacytoid myoepithelial cells in pleomorphic adenoma and malignant plasmacytoid myoepithelioma cells were investigated morphologically. The cells of both tumors were plasmacytoid in appearance and sheet-like. Immunohistochemically, they were positive for keratin, vimentin, and S-100 protein, and negative for alpha-smooth muscle actin. In the malignant cells, large nuclei with irregular nuclear membranes and distinct nucleoi and occasional intranuclear inclusions and nuclear grooves were seen. Ultrastructural findings showed that the benign cells were richer in intermediate filaments and had fewer mitochondria. The intranuclear inclusions and nuclear grooves of the malignant cells were caused by invagination of the irregular nuclear membranes. Taken in their entirety, the above light microscopical nuclear findings may be useful as an adjunct for distinguishing malignant from benign plasmacytoid neoplastic myoepithelial cells of the salivary gland.