Endothelial cell neoplasms

There are two murine models of endothelial cell neoplasms generated by subcutaneous injection of endothelial cells. One uses murine endothelial cells transformed with the middle T antigen of the murine polyoma vims, and the other uses endothelial cells derived from a spontaneously arising hemangioendothelioma The endothelial... 

FIGURE 16.2 Children with endothelial cell neoplasms. The first (left) case is that of a 10-month-old girl with an endothelial cell neoplasm involving the upper extremity. Bleeding and ulceration frequently accompany these lesions. Her lesion shows some signs of involution, as... 

CLINICAL RELEVANCE OF THE ENDOTHELIAL CELL NEOPLASM MODEL... 

Finally, dietary antioxidants may affect cell growth and possible tumorigenesis. When considering the treatment of endothelial cell neoplasms, limiting cell proliferation is one key aspect of an antiangiogenic strategy. Cyclins are molecules that directly stimulate cell division, and cyclin-dependent kinases (CDK) are needed to activate cyclin molecules. Thus the cyclin pathways represent an important target for tumor suppressors to inhibit. Two known tumor suppressor proteins that act in this maimer are... 

Dietary chemopreventive strategies aimed at inhibiting angiogenesis are an alluring option to treat a variety of neoplasms. While it is unlikely that one approach will fit all cancers, it is imperative to develop models that permit experimental manipulation to identify optimal formulations of these naturally occurring compounds. As in vivo models become more standardized, the rate of data accumulation and the ability to define how dietary compounds affect signal transduction, gene expression, and cell behavior will be enhanced. Endothelial cell neoplasms are well suited for these purposes and should be utilized to collect in vivo data to increase the likelihood of success once clinical trials with human subjects are initiated. 

The existence of a barrier between the blood and testes is indicated by the absence of staining in testicular tissue after the intravascular injection of dyes. Morphological studies indicate that the barrier lies beyond the capillary endothelial cells and is most likely to be found at the specialized Sertoli-Sertoli cell junction. It appears that Pgp, the efflux transporter protein, also plays a role in forming this blood-testis barrier. This protein probably plays a role in preventing certain chemotherapeutic agents from reaching specific areas of the testis and thus hinders treatment of the neoplasm. 

Several determinants that are associated with endothelial cells have been applied to the recognition of vascular neoplasms of soft tissue. We will discuss the varying degrees of sensitivity and specificity of these determinants. 

VEGFR3 is a transmembrane protein that is also known as tyrosine-protein kinase receptor FLT4 it is encoded by a gene at chromosomal locus 5q33-qter and is expressed exclusively by lymphatic endothelial cells. In similarity to PPN, VEGFR3 is seen in non-neoplastic lymphatic vessels and in many vascular neoplasms. However, it is more selective than PPN. 

Kaposi s sarcoma is more common since the advent of acquired immunodeficiency syndrome (AIDS), and in most cases it is a metastatic neoplasm in the lung. Kaposi s sarcoma follows lymphatic pathways in the lung and often involves lymph nodes. The neoplastic cells are spindle-shaped (Fig. 12.12) and immunostain for vimentin and endothelial cell markers such as CD31 (Fig. 12.13). 

Rare neoplasms composed of endothelial cells resembling epithelial mesotheliomas are referred to as pseudomesotheliomatous epithelioid hemangioendothelioma or as epithelioid hemangioendothelioma mimicking... 

Primary hepatic malignant neoplasms may develop from hepatocytes, bile duct epithelium, endothelial cells, or lymphoid cells. Most primary malignant hepatic neoplasms are epithelial in origin, such as hepatocellular carcinoma and cholangiocarcinoma. Mesenchymal tumors such as angiosarcoma and epithelioid hemangio-endothelioma, and other sarcoma and lymphomas are rare and represent a minority of primary hepatic neoplasms (Table 17.1). 

S-100 protein reactivity generally should be considered as melanomas. This is especially true if concomitant positivity is obtained for HMB-45, HMB-50, tyrosinase, or MART-1, because the latter four markers are only rarely associated with nerve sheath tumors. Despite the production of collagen type IV by nerve sheath cells, the immunohistochemical detection of this marker has limited value in the diagnosis of schwannian neoplasms because cells with smooth muscle, endothelial, and myo-fibroblastic differentiation may also synthesize it. 

Some epithelial mesotheliomas are composed of small cysts formed by uniform cuboidal mesothelial cells and associated numerous blood vessels (Fig. 12.68). This type of mesothelioma may be difficult to differentiate from a vascular neoplasm. The epithelial mesothelial cells may contain intracytoplasmic hemosiderin (Fig. 12.69). The immunophenotype of such neoplasms is identical to that of other epithelial mesotheliomas. The vascular proliferation may be related to an endothelial growth factor produced by neoplastic mesothelial cells.Adenomatoid tumors are localized benign mesothelial proliferations that most frequently occur in the epididymus and cornua of the uterus.Adenomatoid tumors have been identified in the adrenal gland and pancreas. These tumors are formed by uniform small cuboidal cells and can appear invasive. They express keratin and other markers of mesothelial cells and have the characteristic ultrastruc-tural features of mesothelial cells. Adenomatoid tumors have also been reported in the pleura. Hyperplastic... 

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