Basement membrane in Kaposi's sarcoma: an immunohistochemical and ultrastructural study

Cutaneous vascular proliferations. Part III. Malignant neoplasms, other cutaneous neoplasms with significant vascular component, and disorders erroneously considered as vascular neoplasms

In this third and last part of our review of cutaneous vascular proliferations we include malignant vascular neoplasms and a group of heterogeneous cutaneous neoplasms characterized by a significant vascular component. We also review some disorders that, in our opinion, have been erroneously considered as vascular neoplasms. We review the epidemiologic, histogenetic, clinical, and histopathologic aspects of Kaposi's sarcoma in its four distinctive variants (classic, African-endemic, immunosuppressive drug-associated, and AIDS-associated Kaposi's sarcoma). There is still controversy about whether Kaposi's sarcoma represents a reactive vascular proliferation or a true neoplastic proliferation. In any event, most authors believe that Kaposi's sarcoma does not produce metastatic disease, but rather develops in multifocal fashion. However, Kaposi's sarcoma may cause death, especially in immunosuppressed patients. Epithelioid hemangioendothelioma, Dabska's tumor, and retiform hemangioendothelioma are examples of low-grade angiosarcoma. In contrast, cutaneous angiosarcomas, including the clinical variants of angiosarcoma of face and scalp in elderly patients, angiosarcoma associated with lymphedema, and radiation-induced angiosarcoma are highly aggressive neoplasms with poor prognosis and most patients die within a short period after presentation. A group of benign and relatively frequent cutaneous neoplasms, including multinucleate cell angiohistiocytoma, angiofibroma, angioleiomyoma, angiolipoma, cutaneous angiolipoleiomyoma, and cutaneous angiomyxoma are here covered because of their significant vascular component. Finally, we review briefly a series of cutaneous disorders that have been erroneously considered as vascular neoplasms. Kimura's disease is an inflammatory reactive condition of unknown origin, "benign" angioendotheliomatosis is a reactive intravascular proliferation of endothelial cells that occurs in the skin as a response to a variety of stimuli, "malignant" angioendotheliomatosis is an intravascular lymphoma, and acral pseudolymphomatous angiokeratoma of children (APACHE) is better interpreted as a pseudolymphoma.

Major basement membrane components in Kaposi's sarcoma, angiosarcoma and benign vascular neogenesis

Recent cell biologic studies have emphasized the importance of the basement membrane (BM) and its molecular components in angiogenesis. We immunostained 60 angioproliferative lesions (angiosarcoma, sclerosing hemangioma of skin, pyogenic granuloma, capillary hemangioma, lymphangioma, glomangioma and granulation tissue) and 23 cases of Kaposi's sarcoma (KS) for the major macromolecular components laminin, collagen type IV, fibronectin and heparan sulfate proteoglycan (HSPG). Normal structures served as aggregate controls in each group, and semiquantitative scoring reflected the degree of consistency of staining about blood and lymphatic endothelium and vascular sheath (pericyte/smooth muscle) within and peripheral to each lesion. Benign and reactive vasoproliferations consistently maintained immunoreactivity for each BM component around endothelium and sheath components of blood vessels. Angiosarcoma showed from 20 to more than 60% less consistent immunoreactivity by comparison, although the score variances were greater than for non-malignant lesions. Staining about blood vessel endothelium was both strong and consistent among histologic stages in KS with the exception of HSPG, which was weakly immunoreactive in all stages. Marked selective HSPG loss was characteristic only of KS and normal lymphendothelium, and in the light of evidence for a role for HSPG in the assembly and maintenance of BM, suggests that reduced HSPG may be responsible for the loss of ultrastructural integrity of perivascular BM in both.

Ultrastructural development of Kaposi's sarcoma in relation to the dermal microvasculature

Ultrastructural subtypes of endothelial cells in Kaposi's sarcoma were compared with lymphatics and the normal dermal microcirculation in different stages of lesional development. In the earliest patch stage, lymphatic channels, recognised by their dissecting growth pattern and a lack of a basal lamina and pericytes, were prominent. Venous endothelium was recognised by virtue of its multilaminated basal lamina and often showed markedly irregular luminal and abluminal cytoplasmic projections. As the histological stage progressed toward spindle cells, venous endothelium showed a tetrad of changes: dissolution of the basal lamina; fragmentation and disappearance of the pericyte sheath, decreased and often rudimentary intercellular junctions and markedly reduced numbers of Weibel-Palade bodies. These were also features of spindle cells, which were rarely seen to emerge from narrow vascular channels of indeterminate type. Spindle cells showed sparse intercellular junctions and minimal basal lamina but no Weibel-Palade bodies. These progressive venous alterations thus resulted in a mixed intermediate subtype of endothelium with the morphological traits resembling lymphatics as well as venous blood vessels. The mixed subtype included endothelial tubes surrounded by a complete basal lamina but lacking pericytes, and much more commonly, tubes with pericytes but a scanty basal lamina. Both forms had remarkably few or no Weibel-Palade bodies. In the spindle cell stage, normal vessels were largely replaced by the mixed subtype and an indeterminate type of frequently disrupted endothelial tube which lacked a basal lamina as well as a pericytic investment. Dissecting lymphatic channels could not be confidently distinguished from the latter vessels.(ABSTRACT TRUNCATED AT 250 WORDS)

Distribution of basement membrane-associated heparan sulfate proteoglycan in idiopathic and AIDS-associated Kaposi's sarcoma

In the present study we analyzed the immunohistochemical distribution of different major basement membrane (BM) components with special emphasis on the BM-associated heparan sulfate proteoglycan (HSPG) in early and late stages of Kaposi's sarcoma (KS), both of idiopathic and AIDS-associated origin. In early KS all BM components tested were found surrounding the small clefts of tumour vessels. Heparan sulfate proteoglycan showed the weakest and often fragmented pattern of staining. In the late, nodular sarcomatous form of KS individual tumour cells were surrounded by a BM composed of collagen IV, laminin and fibronectin, while heparan sulfate proteoglycan was not detectable in most cases. Neither between idiopathic and AIDS-associated KS nor between cutaneous and visceral lesions were significant differences in the staining pattern. Our findings of a rather selective expression of various BM-components and the known distribution in normal blood and lymphatic capillaries raises the hypothesis that KS-cells may be derived from cells of lymphaticovenous differentiation.

Cytomegalovirus in intraoral Kaposi's sarcoma

Intraoral Kaposi's sarcomas from five patients with AIDS were examined for the presence of cytomegalovirus (CMV) DNA by in situ hybridization using a biotin-labeled CMV DNA probe and by Southern blot analysis. CMV DNA was detected in two of the five intraoral Kaposi's sarcomas. The CMV DNA was localized to the nuclei of well-differentiated endothelial cells lining well-formed blood vessels, but was not detected in the spindle-shaped cells. Southern blot analysis confirmed the presence of CMV DNA in both lesions. These findings support the concept that CMV may be involved in the neoplastic transformation of the endothelial cells that comprise Kaposi's sarcoma.

Immunohistochemical differentiation between lymphangiographically verified lymphatic vessels and blood vessels

In order to investigate the antigen profile in human lymphatic vessels when compared with blood vessels, postmortem retrograde lymphangiography was done via the thoracic duct on six patients. Formalin fixed, paraffin embedded tissue was stained immunohistochemically for Factor VIII-Related antigen (F VIII R:Ag), with Ulex Europaeus 1 lectin (UEA-1) and for laminin. The results show that the endothelium of blood vessels and lymphatics at all levels of the lymphatic system react positively following staining for Factor VIII-R:Ag and with UEA-1 lectin. The staining for F VIII R:Ag was generally weaker in the endothelial cells lining lymphatic vessels. Staining for the basement membrane component laminin can be used to distinguish lymphatic capillaries and smaller lymphatic collecting vessels from blood vessels.

Intraoral Kaposi's sarcoma: a correlated light microscopic, ultrastructural, and immunohistochemical study

Oral mucosal lesions of Kaposi's sarcoma are a common finding in patients with acquired immunodeficiency syndrome (AIDS). The histologic features of Kaposi's sarcoma vary, depending on the clinical stage of the lesion. Endothelium-lined vessels are the principal feature of early, macular lesions, while spindle cells dominate late-stage, nodular lesions. The histogenesis of both components remains controversial. In this study, biopsy specimens of intraoral Kaposi's sarcoma from 10 patients with AIDS were studied by light and electron microscopic examination and by immunoperoxidase staining with the endothelial markers, factor VIII-related antigen and Ulex europeaus agglutinin I. The results of this study support a vascular origin for both the endothelium-lined vessels and the spindle cells. The latter appear to represent vascular endothelial cells in various stages of differentiation. The histologic features that are useful in the diagnosis of intraoral Kaposi's sarcoma are reviewed.

Ultrastructural findings in oral Kaposi's sarcoma (AIDS)

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.

The extracellular matrix in oral Kaposi sarcoma (AIDS): the immunohistochemical distribution of collagens type IV, V, VI, of procollagens type I and III, of laminin and of undulin

Twelve oral AIDS-associated Kaposi sarcomas (KS) were studied for the distribution of extracellular matrix components using indirect immunofluorescence. Staining for basement membrane (BM) components revealed two distinct patterns of distribution: a delicate and partly fragmented lining of BMs around sinusoid-like vascular spaces or an occasional diffuse interstitial fluorescence in the tumour stroma; or an irregular broad rim of fluorescence in walls of larger blood vessels. These findings support a vascular cell origin of the endothelial- and spindle cell component in KS. The tumour stroma was almost completely negative for collagen type V and undulin, whereas an intensive fluorescence was noted for procollagens type I, III and collagen type VI. In areas adjacent to KS a loss of procollagens type I and III, collagens type V, VI and undulin was noted. An intimal sheath of collagen type V was usually absent from blood vessels of the tumour or the peritumourous connective tissue. Immunohistochemical findings indicate that the preexisting interstitial connective tissue matrix is destroyed during tumour invasion and that subsequently procollagens type I, III and collagen type VI are synthesized de novo by cells of the tumour stroma.