Ultrastructural findings in oral Kaposi's sarcoma (AIDS)

Abstract

Ten biopsies of oral Kaposi's sarcoma were examined histologically and ultrastructurally. Histologically, early and late tumor stages could be differentiated. On the Ultrastructural level, endothelial‐like and spindle‐shaped tumor cells were revealed. Tumor cells associated with vessel‐like spaces showed partly interrupted basal membranes, Weibel‐Palade bodies, desmosomes and tight‐junctions, while spindle‐shaped cells lacked these Ultrastructural features of endothelial cells. Within the cytoplasm of endothelial‐like cells, aggregates of tubular structures were observed. Histological and Ultrastructural findings in oral Kaposi sarcoma are comparable to those of such other organs as skin and intestines. The Ultrastructural findings indicate an endothelial origin, at least of endothelial‐like tumor cells.

Ultrastructural findings in clinically uninvolved oral mucosa of patients with HIV infection

“…studies in these cases revealed protrusion of endothelial ceUs, vascu!ar slit-like channels, sparseness of intercellular junctions, and extravasated erythrocytes (10,11). All of these phenomena, common and essential changes of ear!y KS stage (5,6,15), were a!so found in our study of uninvo!ved ora! mucosa.…”

“…Furthermore, hemosiderin, eosinophilic bodies and extravasated erythrocytes as well as plasma cells and lymphocytes were frequently observed in KS lesions (5,6,14), the proportion of each component varying with the clinical stage of the lesion. While the histological appearance of late-stage KS lesions, clinically presenting as nodules, is dominated by spindle cells with interspersed bloodfilled clefts, early KS lesions, clinically appearing as macules, are composed predominantly of endothelium-lined, vessel-hke structures (6,15). The appearance of cuboidal endothelial cells with enlarged nuclei and partially incomplete formation of the basal membranes has been considered to be the earliest ultrastructural hint for neoplastic growth (5).…”

“…The histopathologic pattern of KS is characterized by an increase in capillary growth: angiogenesis is manifested by multiple, often densely packed vascular, slit-like channels lined by enlarged endothelial cells. In later stages of KS extravasation and intervascular spindle-shaped cells become more prominent (5,6). Recently, atypical vascular proliferation with vessels lined by cuboidal endothelial cells protruding into the lumina has been described in cutaneous nodules of cat-scratch disease occurring in the course of HIVinfection (7-9).…”

Kaposi sarcoma-associated herpesvirus (KSHV) induces heme oxygenase-1 expression and activity in KSHV-infected endothelial cells

“…Intracellular junctions between neoplastic endothelial cells are frequently defective allowing the extravasation of large numbers of erythrocytes from vessel lumens into the surrounding tissue. [50][51][52][53] These renegade cells become more numerous as the disease progresses and abnormal networks of slitlike vascular spaces expand. Erythrophagocytosis by KS cells is also a common feature.…”

“…Because of the potential for increased exposure of KS cells to free heme and heme-containing proteins in KS tissue, [50][51][52][53][54] we investigated the possibility that HO-1 up-regulation might affect the response of KSHV-infected cells to heme. Overexpression of HO-1 A indicates apoptosis; TNFR1, tumor necrosis factor receptor 1; absent, protein present in mock-infected cells but not in KSHV-infected cells (fold change cannot be called); CA, cell adhesion; CD, cell division; FK506, tacrolimus; GAP, GTPase-activating protein; T-LAK, lymphokine-activated killer cells with T-cell phenotype; MAPKK, mitogen-activated protein kinase kinase; CS, cell shape; DR, DNA repair; M, metabolism; GTP, guanosine 5Ј-triphosphate; O, other; IFN, interferon; PS, protein sorting; T, transcription; TGFB, transforming growth factor beta; TG, tumorigenesis; and U, unknown.…”