Benign hemangioma of the mediastinum is rare. This slowly growing tumor is described as well circumscribed, cystic, hemorrhagic tumor. Histologically it can be differentiated into capillary or cavernous form. We present a case of mediastinal hemangioma. A 20-year-old-man was presented with a slowly growing posterior mediastinal mass of 6 years duration, 8x6 cm in size. The mass was relatively well defined but focally invasive. Microscopically, it was differentiated into vessels of capillary, cavernous, and venous patterns. A solid cellular proliferation with inconspicuous capillary lumens was focally seen. The stroma between variable-sized vessels showed marked myxoid change associated with some smooth muscle bundles and adipose tissue. Ultrastructurally, areas of solid cellular proliferation showed formation of lumens. These lumens were lined by active endothelial cells showing plasmalemmal vesicles and Weibel-Palade bodies on the abluminal surface.
Adipose Tissue ; Capillaries ; Cell Proliferation ; Endothelial Cells ; Hemangioma* ; Mediastinum ; Muscle, Smooth ; Weibel-Palade Bodies

Multiple satellite pyogenic granuloma developed on the left upper back of a 14-year-old boy after excision of a hemangioma-like lesion. He has had nevus flammeus on the left upper arm since birth with fine linear telangietasiae around the main lesions. Histopathology showed the capillary proliferation in the dermis, and transmission electron microscopy revealed multiple Weibel-Palade bodies, considered an early endothelial cell marker, in the cytoplasm of the endothelial cells. We believe this patient may have the propensity to develop different angiomatous lesions.
Adolescent ; Arm ; Capillaries ; Cytoplasm ; Dermis ; Endothelial Cells ; Granuloma, Pyogenic* ; Humans ; Male ; Microscopy, Electron, Transmission ; Parturition ; Port-Wine Stain ; Weibel-Palade Bodies

Primary angiosarcoma of the female reproductive system is extremely rare, and its management is not well understood. We experienced a very rare case of angiosarcoma arising in the uterus of a 37-year-old woman who presented abdominal distension. At laparotomy, the uterus was observed to be enlarged and deformed by multilobulated hemorrhagic mass. Tumor deposits were present on both ovaries and the omentum. The operation consisted of total abdominal hysterectomy with salpingo-oophorectomy, and omentectomy. Microscopic examination showed that the tumor consisted mostly of solid sheets of pleomorphic and spindle cells forming irregular, communicating cleft-like spaces. Well-formed vascular channels lined by atypical endothelial cells were seen in differentiated areas. Some vessels were partially lined by normal endothelial cells and partially by neoplastic endothelial cells. Papillary architecture composed of epithelioid tumor cells was noted in a focal area. The tumor cells were immunoreactive for factor VIII-related antigen, Ulex europaeus agglutinin-1, CD31 and CD34. Weibel-Palade bodies were not seen in the tumor cells. She received adjuvant chemotherapy, but died 13 months after the diagnosis.
Adult ; Chemotherapy, Adjuvant ; Diagnosis ; Endothelial Cells ; Female ; Hemangiosarcoma* ; Humans ; Hysterectomy ; Laparotomy ; Omentum ; Ovary ; Ulex ; Uterus* ; von Willebrand Factor ; Weibel-Palade Bodies

BACKGROUNDThe release of Weibel-Palade Bodies (WPB) is a form of endothelial cell activation. But the signal transduction pathway leading to WPB release is not yet defined. We hypothesized that small G-protein rac1 and reactive oxygen species (ROS) mediate the ligand induced release of Weibel-Palade Bodies.

METHODSWe tested this hypothesis by using wild-type and mutant adenoviral rac1 expression vectors, and by manipulating the production and destruction of superoxide and hydrogen peroxide in human aortic endothelial cells (HAEC).

RESULTSThrombin (1.0 Unit, 30 min) induced the increase of WPB release by 3.7-fold in HAEC, and that H2O2 (0.1 mmol/L, 30 min) induced by 4.5-fold. These results correlated with thrombin-stimulated activation of rac-GTP binding activity by 3.5-fold, and increase of ROS production by 3.4-fold. The dominant negative adenoviral rac-N17 gene transfer dramatically inhibited the release of WPB by 64.2% (control) and 77.3% (thrombin-stimulation), and decreased ROS production by 65.5% (control) and 83.6% (thrombin-stimulation) compared with non-infected cells, respectively. Anti-oxidants, catalase and N-acetyl-cysteine significantly decreased the release of WPB by 34% and 79% in control cells, and further decreased by 63.6% and 46.7% in rac-N17 transferred cells compared with non-infected cells. We also confirmed that rac1 was located upstream of ROS in the WPB release pathway.

CONCLUSIONSSmall G-protein rac1 medicates ligand-induced release of Weibel-Palade Bodies in human aortic endothelial cells, and the signal pathway of WPB release is a rac1-dependent ROS regulating mechanism.

Aorta ; ultrastructure ; Endothelial Cells ; ultrastructure ; Humans ; Reactive Oxygen Species ; Signal Transduction ; Thrombin ; pharmacology ; Weibel-Palade Bodies ; physiology ; rac1 GTP-Binding Protein ; physiology

Endothelial cells were isolated from the intima of Sprague-Dawley rat aorta with 0.2% collagenase solution and cultured in MCDB 131 medium. All endothelial cells regardless of passages and the freezing-thawing were cultured in M-199, alpha-MEM, and MCDB 131 media. Thereafter, the morphological findings of the cells were observed under light and electron microscopes. The activities of nitric oxide synthetase of endothelial cells were investigated with NADPH-diphorase staining. Production of von Willebrand factor, cytoskeletal proteins, and extracellular matrix proteins in endothelial cells was identified with PAP. By treating with 0.2% collagenase solution for 30 minutes, and then incubating the cells in MCDB 131 medium for 3 days, only endothelial cells could be separated. Endothelial cells formed a monolayer with typical cobblestone pattern (polygonal-shaped morphology) 7-10 days after seeding. The growth patterns of endothelial cells were similar regardless of their cultured states (primary cultured cells, subcultured or thawed). The existence of nitric oxide synthetase, von Willebrand factor, beta-actin, fibronectin, and laminin in endothelial cells was confirmed. However, above-mentioned materials were quantitatively less in cells grown with MCDB 131 medium compared to those cultured with M-199 and alpha-MEM. Weibel-Palade bodies were observed by transmission electron microscopy. Cultured cells in MCDB 131 medium compared to those cultured with M-199 and alpha-MEM were relatively fewer in number of rough endoplasmic reticulum, mitochondria, free ribosome, vesicle, and liposome and especially showed the absence of basement membrane. Taken together, the cultivation of endothelial cells from the intima of rat aorta was possible. Endothelial cells in vitro synthesized various materials such as von Willebrand factor etc. and had characteristic organelles (Weibel-Palade body etc.). It suggested that it would be more advantageous to culture the endothelial cells in M-199 with 20% fetal bovine serum and alpha-MEM with 10% bovine calf serum rather than in MCDB 131 endothelial cell culture medium only with 0.7% dialyzed serum to maintain characteristics of endothelial cells in vivo
Actins ; Animals ; Aorta* ; Basement Membrane ; Cells, Cultured ; Collagenases ; Cytoskeletal Proteins ; Endoplasmic Reticulum, Rough ; Endothelial Cells* ; Extracellular Matrix Proteins ; Fibronectins ; Laminin ; Liposomes ; Microscopy, Electron, Transmission ; Mitochondria ; Nitric Oxide Synthase ; Organelles ; Rats* ; Rats, Sprague-Dawley ; Ribosomes ; von Willebrand Factor ; Weibel-Palade Bodies