Histogenesis of Kaposi's sarcoma in patients with and without acquired immune deficiency syndrome (AIDS)

Kaposi’s sarcoma-associated herpesvirus vFLIP promotes MEndT to generate hybrid M/E state for tumorigenesis

Kaposi’s sarcoma (KS) is an angioproliferative and invasive tumor caused by Kaposi’s sarcoma-associated herpesvirus (KSHV). The cellular origin of KS tumor cells remains contentious. Recently, evidence has accrued indicating that KS may arise from KSHV-infected mesenchymal stem cells (MSCs) through mesenchymal-to-endothelial transition (MEndT), but the transformation process has been largely unknown. In this study, we investigated the KSHV-mediated MEndT process and found that KSHV infection rendered MSCs incomplete endothelial lineage differentiation and formed hybrid mesenchymal/endothelial (M/E) state cells characterized by simultaneous expression of mesenchymal markers Nestin/PDGFRA/α-SAM and endothelial markers CD31/PDPN/VEGFR2. The hybrid M/E cells have acquired tumorigenic phenotypes in vitro and the potential to form KS-like lesions after being transplanted in mice under renal capsules. These results suggest a homology of KSHV-infected MSCs with Kaposi’s sarcoma where proliferating KS spindle-shaped cells and the cells that line KS-specific aberrant vessels were also found to exhibit the hybrid M/E state. Furthermore, the genetic analysis identified KSHV-encoded FLICE inhibitory protein (vFLIP) as a crucial regulator controlling KSHV-induced MEndT and generating hybrid M/E state cells for tumorigenesis. Overall, KSHV-mediated MEndT that transforms MSCs to tumorigenic hybrid M/E state cells driven by vFLIP is an essential event in Kaposi’s sarcomagenesis.

Kaposi’s sarcoma manifests as multifocal lesions with spindle cell proliferation, intense angiogenesis, and erythrocyte extravasation. Although the origin and malignant nature of KS remain contentious, it is established that KSHV infection with concomitant viral oncogene expression in normal cell progenitors causes KS. The mechanism of KSHV oncogenesis could be revealed through a reproduction of KS by infection of normal cells. This study reports that the KSHV infection of mesenchymal stem cells initiates mesenchymal-to-endothelial transition (MEndT) that generates mesenchymal/endothelial (M/E) hybrid state cells. The hybrid M/E cells acquired tumorigenic phenotypes, including tumor initiation, angiogenesis, migration, and the potential to form KS-like lesions after transplanted in mice. This finding faithfully recapitulates Kaposi’s sarcoma where proliferating KS spindle cells and the cells that line KS-specific aberrant vessels are also found to exhibit the hybrid M/E phenotype. We also found that KSHV-encoded viral FLICE inhibitory protein (vFLIP) plays a crucial role in promoting MEndT and the generation of M/E state cells. These results provide a new layer of evidence for KSHV-infected MSCs being the cell source of KS spindle cells and reveal novel insight into KS pathogenesis and viral tumorigenesis.

Kaposi's Sarcoma: A Clinico-Pathologic Overview

A careful overview of the classical appearances of Kaposi's sarcoma (KS) as well as of its variants were reviewed from the clinical and pathological point of view. The growth phases (stages) and the cellular patterns were histopathologically compared with emphasis on the developmental progression of disease as well as mitotic activity. Other morphological aspects were also assessed such as the features of the early phases and the incidence of hyaline bodies. One hundred and forty-three lesions from 96 patients mostly of the Italian sporadic type were investigated. A complete list of those entities which should be considered in differential diagnosis is shown and the dilemma of whether KS is a neoplasia or a hyperplasia is discussed.

Lymphatic differentiation in classic Kaposi's sarcoma: patterns of D2-40 immunoexpression in the course of tumor progression

The recent development of lymphatic endothelium-specific immuno-indicators has given rise to research on the histogenesis of Kaposi sarcoma (KS), specifically focusing on its lymphatic root and differentiation. D2-40 is a new lymphatic marker that recognizes podoplanin and is easily applied to formalin-fixed paraffin-embedded human tissues. This study examined D2-40 immunoexpression in 178 classical KS lesions using immunohistochemical methods. D2-40 immunoexpression was also examined in 63 non-KS soft tissue lesions to test the reliability of D2-40 monoclonal antibody in the pathological diagnosis of KS. D2-40 immunoreactivity was detected at all of the KS lesions and in lymphangioma and nonneoplastic lymphatic endothelium. There was no significant relationship between the extent of D2-40 staining and histopathological stage; however, there was a positive correlation between the staining intensity and histopathological stage in KS cases. D2-40 immunoreactivity was detected at all histopathological stages of KS and may be added to the routine immunohistochemical panel used for the differential diagnosis of KS. Widespread D2-40 protein expression is evidence of a lymphatic origin or the differentiation of neoplastic cells in KS, and D2-40 expression increases with tumor progression.

Monoclonal antibody D2-40, a new marker of lymphatic endothelium, reacts with Kaposi's sarcoma and a subset of angiosarcomas

There is controversy over the histogenesis of Kaposi's sarcoma (KS) from lymphatic or blood vessel endothelium. D2-40 is a novel monoclonal antibody to an Mr 40,000 O-linked sialoglycoprotein that reacts with a fixation-resistant epitope on lymphatic endothelium. We sought to establish the selectivity of D2-40 for lymphatic endothelium in normal tissues and compare its reactivity with the expression of the widely used vascular endothelial marker CD31 in a series of 62 formalin-fixed and paraffin-embedded vascular lesions including KS. In normal tissues, D2-40 stained the endothelium of lymphatic channels but not of blood vessels, including arteries and capillaries defined by reactivity with the blood vessel endothelial marker PAL-E. In our series of vascular lesions, D2-40 stained lymphangiomas (10/10), benign tumors of undisputed lymphatic origin, but not benign neoplasms or tumorlike lesions of blood vessel origin, including hemangiomas (0/10), glomus tumors (0/3), angiolipomas (0/2), pyogenic granulomas (0/2), vascular malformations (0/2), hemangiopericytoma (0/1), or hemangioendothelioma (0/1). D2-40 stained all cases of cutaneous KS (24/24) at all stages of progression, including patch, plaque, and nodular stages, supporting the concept that this disease originates from a cell type capable of undergoing lymphatic differentiation. D2-40 also stained three of seven angiosarcomas, indicating that a subset of these tumors can undergo at least partial differentiation along the lymphatic endothelial lineage and could be classified as lymphangiosarcomas. In comparison, CD31 was expressed in all benign and malignant vascular lesions, except for glomus tumors (0/3) and 5/10 lymphangiomas, in which staining was absent. We conclude that D2-40 is a new selective marker of lymphatic endothelium in normal tissues and vascular lesions and is valuable for studying benign and malignant vascular disorders in routinely processed tissue specimens.

A novel monoclonal antibody specific for lymphatic endothelium

The difficulty of identifying and differentiating lymphatic and blood microvessels in tissue sections can be overcome by a monoclonal antibody specific for lymphatic endothelium. Unfortunately, the only known antibody also reacts with the endothelium of some blood vessels. The technique of double immunization (passive, with an antiserum to blood endothelium, and active, with a suspension of lymphatic endothelial cells) was, therefore, used to increase the chances of recognizing specific lymphatic antigens by the mouse immune system. The monoclonal antibody obtained, LyMAb, a G1 immunoglobulin, reacted strongly with the endothelium of bovine thoracic duct, mesenteric collecting vessels and lymphatic vessels of gallbladder and lymph nodes and moderately with those of the intestinal wall. Blood vessels (intercostal arteries, azygos vein and blood microvessels of all organs tested) were consistently negative. The antibody was species-specific and did not react with formalin-fixed, paraffin-embedded sections. Cross-reactivity was limited to some connective tissue fibres and scattered cells in the lymph node parenchyma, intestinal villi and hepatic lobules.

Lymphangioma-like Kaposi's sarcoma: etiology and literature review

Much confusion surrounds a rare and occasionally described variant of Kaposi's sarcoma (KS) known as lymphangioma-like or bullous KS. We describe the typical clinical and histologic features and elucidate the etiologic cell in lymphangioma-like KS. A computer-based review of the English-language literature was performed. Routine histologic and immunoperoxidase techniques were performed on formalin-fixed tissue. Immunoperoxidase staining for anti-CD31, anti-CD34, and anti-factor VIII-related antigen suggests that the etiologic cell of origin is the vascular endothelial cell. Lymphangioma-like KS has been described for more than a century and given various names. Dilated vascular spaces correlate with the clinically bullous lesions, which are veritable KS and not a secondary reaction to it.

Targetoid hemosiderotic hemangioma- a dynamic vascular tumor: report of 3 cases with episodic and cyclic changes and comparison with solitary angiokeratomas

BACKGROUND

Both targetoid hemosiderotic hemangiomas (THH) and solitary angiokeratomas (SAK) are acquired vascular malformations formed by superficial vascular ectasias possibly caused by trauma.

OBJECTIVE

We compare the clinicopathologic findings of THHs with those of SAKs and report the clinicopathologic findings of 3 singular cases of THH affected by cyclic or episodic morphologic changes.

METHODS

We performed a clinicopathologic study on 33 cases of THH and compared this group with 20 cases of SAK. On selected cases, histochemical and immunohistochemical analyses were evaluated.

RESULTS

Overlap of all the clinical and pathologic features studied were identified for THH and SAK. Clinically, they both commonly exhibited a brown or black papule located over the lower extremities that mimicked a melanocytic lesion. Histologically, they both had ectatic papillary dermal vessels with overlying epidermal hyperplasia, and adjacent hemosiderin deposits, extravasated red blood cells, lymphocytic infiltrate, and lymphangiectases. Compared with SAKs, THHs were significantly larger (5.3 vs 3.2 mm), more often excised (elliptical excision) than shave or punch biopsied, and had deeper dermal vessel alterations, more frequent dissecting vascular spaces, and more extensive hemosiderin deposits (all P < .01). THHs presenting with episodic changes were significantly larger than those without (11 vs 4.4 mm, P =.001).

CONCLUSION

THHs and SAKs differ in degree, not in type, of clinicopathologic characteristics. This finding suggests that THHs are larger variants of SAKs whose size is the cause of more extensive, prolonged, or recurrent vessel damage. The histologic findings of extravasated red blood cells, hemosiderin, telangiectases, lymphangiectases, and fibrosis implicate trauma in the cause of these acquired vascular malformations.

AIDS-Related malignancies

Neoplasms are a common complication of HIV-infected individuals. The increased survival rates of those with HIV infection may allow the emergence of an increased number of cancers. The new therapeutic regimens may slow the rate of progression by partially restoring the integrity of the immune system.

IL-4R expression in AIDS-KS cells and response to rhIL-4 and IL-4 toxin (DAB389-IL-4)

Interleukin-4 (IL-4) is a pleiotropic cytokine affecting growth and differentiation of various cell types as well as regulating other cytokines. To study the effect of IL-4 on AIDS-related Kaposi's sarcoma (AIDS-KS) cells, we first examined the tumor cells for IL-4 receptor (IL-4R) expression. KS cells express a single 4 kB IL-4R-specific mRNA and 1828 +/- 408 high affinity IL-4 binding sites per cell with a dissociation constant (Kd) of 154 +/- 37 pM. Addition of recombinant human IL-4 (rIL-4) minimally inhibited AIDS-KS cell growth and expression of IL-6. We then studied the effects of a chimeric fusion toxin DAB389-IL-4 which exerts cellular toxicity only on cells expressing IL-4R. DAB389-IL-4 inhibited protein synthesis in AIDS-KS cells at low concentrations (IC50 of 5 x 10(-11) M). This effect was abrogated by neutralizing antibody to IL-4 (25D2). We conclude that KS cells express a functional IL-4R and this receptor could serve as a target for novel therapy with agents such as DAB389-IL-4.

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.

Bullous lesions in Kaposi's sarcoma: case report

Bullous lesions have been only rarely described in Kaposi's sarcoma (KS), and their histopathologic features have never been described in detail. We report a case of bullous lesions of KS in an 82-year-old Italian woman. The patient had typical smooth pale reddish-grey slightly-raised KS plaques on the legs, present for at least 10 years. Several dull grayish-pink blisters (0.5 to 2 cm in diameter) affected both dorsa of her feet and ankles symmetrically. Two punch biopsies were taken, one from an infiltrated KS plaque on the right buttock and the other from a bullous lesion on the right foot. Histopathologically, the late KS plaque on the buttock showed typical features of KS, with an increased number of spindle cells arranged in short bundles and extravasation of erythrocytes. The bullous lesion on the foot showed a full-thickness vascular neoplasm involving the upper and lower dermis and the subcutaneous fat. The upper portion of the lesion contained many newly formed, highly-dilated blood vessels, touching the overlying epidermis and separated from it by a narrow band of collagen and endothelial cells; wide, empty spaces characterized the superficial dermis, in which preexisting venules and bands of collagen associated with non-atypical endothelial cells floated. All these findings would suggest a lymphangiomatous lesion, if the presence of specific diagnostic criteria of KS were not recognizable at a deeper level of the lesion. Various criteria actually suggest that the bullous lesion may be regarded as an epiphenomenon of a KS plaque lesion: (a) full-thickness involvement of the reticular dermis and, in this case, also of the subcutaneous fat; (b) dense and patchy lymphoplasmocytic infiltrate typical of plaque lesions and, much less frequently, of patch lesions; (c) presence of ectatic blood vessels, filled with plasma and erythrocytes (pseudoangiomatous findings), a nonpathognomonic but highly characteristic finding of the plaque lesion; and (d) as in the KS plaque lesions, in the bullous lesion as well the reticular dermis was characterized by an increased number of anastomosing bizarrely shaped vascular spaces lined by non-atypical endothelial cells. We hypothesize that the prevalence of lymphangiomatous differentiation in the upper dermis represents one of the many features of KS lesions. When present, it may correlate with the clinical feature of a blister.

Kaposi's sarcoma cells express the macrophage-associated antigen mannose receptor and develop in peripheral blood cultures of Kaposi's sarcoma patients

The mannose receptor (MR) is a surface 175-kd C-type lectin expressed by macrophages and dendritic cells. MR is involved in removal of effete cells, phagocytosis of mannose-coated particles, pinocytosis, and antigen presentation. Expression of MR was investigated in 17 biopsies of Kaposi's sarcoma (3 AIDS KS, 13 classical KS, and 1 transplant-associated KS) using three anti-MR monoclonal antibodies (3.29, D547, and PAM1). Immunostaining for MR was detected in 94 +/- 7% KS cells with spindle morphology. In normal tissues, MR was expressed by sinus-lining cells of spleen and lymph nodes, but it was not detected in endothelial cells lining normal hematic and lymphatic vessels, hemangioma, hemangioendothelioma, and lymphangioma. Expression of MR in KS cells prompted us to investigate the possibility that they derive from a circulating precursor cell. Peripheral blood mononuclear cells from 16 patients with KS (10 classical, 1 transplanted, and 5 AIDS) were cultured in PHA-conditioned medium for 10 to 14 days. Confluent monolayers of adherent spindle cells were detected in 8 of 11 classical KS, in 5 of 5 AIDS KS patients, and in 0 of 34 control patients. Peripheral-blood-derived KS-like cells were characterized by co-expression of macrophage and endothelial antigens being positive for CD45 (60%), CD68 (98%), MR (70%), CD14 (25%), VE-cadherin (70%), and von Willebrand factor (10%). When the immunophenotype of peripheral-blood-derived adherent cells was compared with that of KS spindle cells of tissue biopsies, it was found that both cell types are VE-cadherin+/MR+/CD68+, that peripheral-blood-derived spindle cells are CD34- and are less frequently stained for CD31 and von Willebrand factor, and that lesional KS cells do not express the leukocyte markers CD45 and CD18. Our findings are consistent with the possibility that KS lesions derive from tissue accumulation and local proliferation of a special subset of macrophages with endothelial features the normal counterpart of which are the sinus-lining cells of spleen and lymph nodes.

Lymphangioma-like variant of Kaposi's sarcoma: clinicopathologic study of seven cases with review of the literature

The clinical and pathological features of seven cases of lymphangioma-like Kaposi's sarcoma (KS) are reported. As with the other subtypes of KS, the lymphangioma-like variant occurs more often in men aged 59-80 years. Clinically, the lesion appears intermingled with the classical forms of KS, but a "bulla-like" appearance recognized in seven of 13 cases has been considered as a clinical hallmark of this variant. Although occasional cases have shown aggressive behavior, the most frequent clinical course is slowly progressive with localized or diffuse involvement of lower limbs. The histological pattern, characterized by permeation of dermal collagen by labyrinthine vascular channels lined by a flattened endothelium, must be differentiated from spindle cell hemangioendothelioma, low-grade angiosarcoma, targetoid hemosiderotic hemangioma, and benign lymphangioendothelioma.

Aneurysmal and haemangiopericytoma-like fibrous histiocytoma

AIM

To describe the clinicopathological features of 33 aneurysmal fibrous histiocytomas (AFH), including five cases with a haemangiopericytoma-like pattern.

METHODS

Thirty three cases of AFH were studied by using routine histology and immunohistochemistry for factor XIIIa, the "cell activity marker" E9 (anti-metallothionein), NK1C3 (CD57), smooth muscle actin (SMA), factor VIII, ulex europaeus agglutinin, JC70A (CD31), and QBEND10 (CD34). The time dependent variation in histopathological features was evaluated by statistical methods (Pearson chi 2, likelihood ratio chi 2).

RESULTS

Of the AFHs, 29 of 33 occurred on the extremities of adults (age range 30 to 50 years), six of which were associated with rapid growth, probably caused by trauma, and pain. Twenty one lesions were thought to be vascular and/or melanocytic lesions, including two melanomas, because of a bluish-black and/or cystic appearance. Histologically, large areas of haemorrhage, up to 50% of the tumour bulk, lacking an endothelial lining were seen in otherwise typical fibrous histiocytomas. Five cases resembled nodular stages of Kaposi's sarcoma. Variable haemosiderin deposition in histiocytes (18/33) and giant cells (11/33) was suggestive of haemosiderotic histiocytoma. A haemangiopericytoma-like pattern was seen in five otherwise indistinguishable cases. On immunohistochemistry, variable reactivity was seen for factor XIIIa (18/30), with E9 (18/30), NK1C3 (19/30), and for SMA (14/30), but labelling for vascular markers was not detected. Early lesions without iron deposition were factor XIIIa positive; late lesions with iron deposition were factor XIIIa negative. Labelling for SMA correlated with prominent sclerosis.

CONCLUSION

AFHs, including a haemangiopericytoma-like variant, have a characteristic time dependent histological and immunophenotypic profile, clearly different from nodular type Kaposi's sarcoma.

Immunostaining for CD31 and CD34 in Kaposi sarcoma

AIMS

To evaluate antibodies directed against CD31 (JC70/A) and CD34 (QBEND/10 and anti-HPCA-1) more extensively in Kaposi sarcoma; to assess their value in routine diagnosis; and to compare them with the traditional endothelial cell markers Ulex europaeus agglutinin 1 (UEA-1) and factor VIII related antigen.

METHODS

Twenty four cases of Kaposi sarcoma were studied retrospectively. All specimens had been fixed in formalin and embedded in paraffin wax. The antibodies were applied using the Streptavidin biotin technique in all cases except for UEA-1, for which an indirect two stage method was used involving peroxidase conjugated anti-ulex as the secondary antibody.

RESULTS

Tumours were classified into those showing angiomatoid or lymphangiomatoid elements and spindle cell lesions. Universal labelling of all lesions and virtually all elements within lesions was seen with the anti-CD34 antibodies QBEND/10 and HPCA-1. Labelling of spindle cells was less consistent with JC70/A but both markers were superior to the traditional endothelial cell markers UEA-1 and factor VIII related antigen.

CONCLUSIONS

These data confirm that Kaposi sarcoma is a tumour of endothelial cell origin. They shed further light on the histogenesis of this complex tumour and demonstrate that immunostaining for CD34 and CD31 can be used as an aid to diagnosis in routinely processed tissue.

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.

Lower extremity lymphedema caused by acquired immune deficiency syndrome-related Kaposi's sarcoma: case report and review of the literature

A case of severe lymphedema of the lower extremity caused by obstruction by human immunodeficiency virus-associated Kaposi's sarcoma is presented. A review of the signs and symptoms of obstructive lymphedema and Kaposi's sarcoma is provided. Early recognition of this clinical entity may allow use of simple preventative measures and help to avoid this life- and limb-threatening situation.

Immunohistochemical localization of transforming growth factor-beta 1 in Kaposi's sarcoma

Immunohistochemical localization of transforming growth factor beta 1 (TGF-beta 1) was studied in Kaposi's sarcoma (KS) tissues obtained from autopsy and biopsy materials of patients with and without acquired immunodeficiency syndrome (AIDS) or human immunodeficiency virus (HIV) infection. There was no difference in the localization and distribution of TGF-beta 1 in KS tissues regardless of the HIV-1 status of the patients. Rabbit polyclonal antibodies to synthetic peptides, corresponding to the first 30 amino acids of mature TGF-beta 1, anti-LC(1-30), and anti-CC(1-30), were used for localization of intracellular and extracellular TGF-beta 1. An antibody to a peptide corresponding to amino acids 266 to 278 of the TGF-beta 1 precursor sequence anti-Pre(266 to 278) was used to detect the TGF-beta 1 precursor and the latency-associated peptide. Intracellular mature TGF-beta 1 was demonstrated in mononuclear cells, presumably macrophages, within KS tumors but not in spindle-shaped KS cells. Extracellular mature TGF-beta 1 was localized in the basement membranes of blood vessels and fibrous capsules of KS tumors. Intracellular reactivity to anti-Pre was localized in vascular smooth muscle cells and pericytes within the tumor, in variable proportions of spindle-shaped KS cells, and also in macrophage-like cells. These cells appear to be the production sites of TGF-beta 1, which may exert paracrine as well as autocrine proliferative effects.

Acquired progressive lymphangioma of the skin following radiotherapy for breast carcinoma

A case of a vascular tumor clinically and pathologically consistent with acquired progressive lymphangioma (benign lymphangioendothelioma) in a 48-year-old woman is reported. The lesion appeared in the skin close to a mastectomy scar 3 years after surgery and radiotherapy for invasive ductal carcinoma. On histologic examination, it mimicked an aggressive vascular neoplasm because of its infiltrative pattern. However, follow-up studies confirmed the benign nature of the lesion, clinically and histologically. This case indicates that acquired progressive lymphangioma may follow radiotherapy and must be considered in the differential diagnosis of other vascular proliferations occurring in the skin of the breast, especially of low-grade postradiation angiosarcoma, a recently described neoplastic entity.

Role of scatter factor and the c-met protooncogene in the pathogenesis of AIDS-associated Kaposi's sarcoma

Kaposi's sarcoma is a highly lethal tumor in patients with sexually acquired AIDS. A number of etiologic agents have been implicated in the development of this disease in this patient population and there is ample evidence that aberrant production of and responsiveness to KS tumor and host cell-derived cytokines plays a central role in the pathogenesis of AIDS-KS. In this review we propose that aberrant expression SF and c-met is central to the pathogenesis of KS. KS is a serious and life-threatening consequence for many patients with AIDS. Unfortunately, current therapeutic strategies for the treatment of this complex neoplasm have met with only limited success. In view of the poor survival rates for AIDS-KS patients which continue to decline at an alarming rate, it is eminently clear that a better understanding of the etiology and pathogenesis of this form of KS is needed if novel therapeutic strategies designed to successfully combat this disease are to be developed. If our hypothesis is validated, one could envision several approaches whereby the modulation of SF/c-met function or production might lead to a reduction in the incidence and severity of KS lesions. Antibody therapy directed against either SF-producing tumor cells or against the c-met receptor might decrease the incidence of new tumors by limiting their clonal expansion and lead to regression of established tumors by blocking SF-mediated tumor cell proliferation and neovascularization. It might also be possible to suppress production of SF or accessory cytokines involved in the induction SF production and thus short circuit SF/c-met growth-promoting effects. We have outlined a novel hypothesis for understanding the mechanism underlying the development of AIDS-associated KS. This is most certainly not the whole story, however. Clearly, other cytokines and alterations in natural host defenses and the immune system contribute significantly to the development of AIDS-associated KS. We believe, however, that recognition of SF/c-met as a participant in this disease is necessary if we are to more fully understand the pathogenesis of AIDS-associated KS.

Kaposi's sarcoma. Epidemiology, pathogenesis, histology, clinical spectrum, staging criteria and therapy

The acquired immunodeficiency syndrome (AIDS) epidemic has had a profound impact on our understanding of Kaposi's sarcoma (KS). Epidemiologic features suggest a sexually transmitted cofactor in the pathogenesis of AIDS-associated KS (AIDS-KS), and several putative agents have received intense scrutiny. Cell culture studies suggest that the angiogenesis of AIDS-KS is stimulated by both human immunodeficiency virus proteins and growth factors that may be involved in the development and progression of AIDS-KS, thereby providing a rationale for new therapeutic interventions. The dermatologist is uniquely qualified to provide care for the majority of patients with KS, as many patients have cutaneous lesions amendable to local therapy (cryotherapy, intralesional therapy, simple excision). Patients requiring more aggressive local therapy (radiation therapy) or systemic therapies (interferon, chemotherapy) can be easily recognized. Standardized staging criteria provide assistance for determining appropriate local or systemic therapy and for evaluating and comparing responses to new therapies. This article reviews the epidemiology, pathogenesis, histologic features, clinical spectrum, staging criteria, and treatment of KS.

Assessment of tumour vascularity as a prognostic factor in lymph node negative invasive breast cancer

The association between tumour vascularity and relapse was examined in 93 patients with lymph node negative (LNN) invasive breast cancer. Factor VIII-related antibody was used to stain the microvessels. Vascularity was defined by the number of vessels per field counted in the area of highest vascular density at 100 x magnification. These vascular counts were divided into three groups of vascular density (group I: < 67, group 2: 68-100, group 3: > 101 vessels/field). Cross-tabulation analysis revealed a significant relationship between vascular density and tumour grade (P = 0.027). No association was found between vascularity and tumour size, tumour type, age or menopausal status. Survival analysis showed no association between vascularity and relapse-free (P = 0.92) or overall survival (P = 0.99). Significant associations between tumour grade and relapse-free (P = 0.0048) and overall survival (P = 0.0064) and between tumour size at the cut off of 15 mm diameter and relapse-free (P = 0.0097) and overall survival (P = 0.0271) were found. When grade was taken into account the effect of tumour size became non-significant (P = 0.059). Our results suggest that assessment of vascularity is not an independent prognostic factor in LNN invasive breast cancer.

Histologic predictors of survival in acquired immunodeficiency syndrome-associated Kaposi's sarcoma

The relationship between 22 histologic variables and survival was investigated in 93 patients with acquired immunodeficiency syndrome (AIDS)-associated Kaposi's sarcoma (KS). All the patients were homosexual men in whom KS was the initial manifestation of AIDS. All patients were followed for at least 12 months or until death. Histologic specimens of the initial KS biopsy were reviewed in a blind manner by two of the authors and were evaluated for the presence of a number of histologic features. In a univariate analysis nodular lesions of KS (upsilon patch or plaque lesions), the absence of hemosiderin, the absence of irregular vascular spaces, and the presence of spindle cell nodules were all significantly associated with increased length of survival. Two variables previously shown to be related to survival (CD4:CD8 cell ratio, initial lesion on lower extremities) were included in a multivariate analysis (Cox model) in addition to the histologic variables. Complete data were available from 85 patients. In the multivariate analysis a higher helper to suppressor T-cell ratio, initial lesion on lower extremities, presence of spindle cell nodules, and nodular histology (upsilon patch or plaque histology) were all significantly associated with increased length of survival. These data suggest that in AIDS-associated KS, as in reticuloendothelial neoplasms, histologic features may be useful in identifying prognostically different subgroups of patients.

Active metabolism of arachidonic acid by Kaposi sarcoma cells cultured from lung biopsies (KS-3); identification by HPLC and MS/MS of the predominant metabolite secreted as the 11,12-epoxy-eicosatrienoic acid

The development of long-term culture of AIDS-KS cells has allowed us to investigate further a possible vascular origin of Kaposi sarcoma. Taking into account the relative specificity of arachidonic acid (AA) metabolism according to cell type, the AA 'cascade' was analyzed in cultured KS-3 cells established from lung biopsies and compared to human umbilical venous endothelial (H-UVE) cells and human myometrial smooth muscle (H-MSM) cells, under basal conditions and after stimulation with vasoactive agents such as histamine or thrombin. Considering strictly the 'prostaglandin' profile given by RIAs, the metabolism of AA was closer, whilst not identical, to H-UVE than to H-MSM cells. However, evaluation of all the eicosanoids released from [3H]AA labeled KS-3 cells revealed that the predominant metabolite was not prostacyclin (PGI2), as suggested from PG RIAs, but an epoxy-eicosatrienoic acid (EET), identified as the 11, 12 isomer by HPLC and MS/MS. The synthesis of this EET is probably cytochrome P-450 monooxygenase dependent. Its potential role in the development of the KS tumor cells is under investigation.

Kaposi's sarcoma: a review of gene expression and ultrastructure of KS spindle cells in vivo

The ultrastructural features and the gene expression pattern of Kaposi's sarcoma (KS) spindle cells in vivo suggest that KS is a tumor of the mixed cell type. The expression pattern of cytokines and cytokine receptors in the tumor lesion, together with the results obtained from in vitro characterization of KS-derived cells, provide evidence that paracrine mechanisms of growth factor action are important for the maintenance of KS. The reports on virus infection of KS cells suggest an indirect role of virus infection in the induction of KS, most likely mediated by immunostimulation and subsequent production of cytokines.

Expression of platelet-derived growth factor and its receptor in AIDS-related Kaposi sarcoma in vivo suggests paracrine and autocrine mechanisms of tumor maintenance

As previously described, proliferation of Kaposi sarcoma (KS)-derived cells in vitro is dependent on the presence of platelet-derived growth factor (PDGF). To test the hypothesis that PDGF may also be a major growth factor for KS cells in vivo, we performed in situ hybridization and immunohistochemical staining for PDGF and PDGF receptors in tissue sections of AIDS-related KS. The data suggest that KS consists of two types of tumor cells. (i) The main population are spindle-shaped cells with elongated nuclei (KS-s cells). They reveal a strong expression of PDGF beta receptors but do not express the PDGF-A and PDGF-B isoforms. (ii) A minor population of KS cells express PDGF beta receptor as well as PDGF-A and PDGF-B (KS-p cells). These cells are often grouped in whorls and surrounding vascular slits. They reveal spherical nuclei with evenly distributed chromatin and inconspicuous nucleoli. PDGF alpha receptor is not expressed in either form of KS cells. The results suggest that the isoforms of PDGF and the PDGF beta receptor are differentially expressed in two different cell types in KS and that PDGF isoforms may contribute to the pathogenesis of KS.

Recognition of heterogeneous lymphokine-activated killer (LAK) receptors on Kaposi's sarcoma cells, endothelial cells, and monocytes/macrophages: Evidence of distinct LAK-cell antigen on Kaposi's sarcoma cells?Potential for use of LAK cells for immunotherapy

The purpose of this study was to determine the potential use of lymphokine-activated killer (LAK) cells against Kaposi's sarcoma (KS) cells. We used chromium release cold-target inhibition assay for understanding the expression of heterogeneous LAK-cell antigens (Ags) on KS cells, endothelial cells (ECs), and monocytes/macrophages (M phi) which could allow for the utilization of LAK-cell immunotherapy in KS without side effects. Our data show that (i) all three cell types express the CD18 Ag of LFA-1 or Leu-CAM, (ii) rare KS cells from eyes cannot cold target-inhibit ECs, (iii) KS cells express a distinct LAK-cell Ag, which we have called LAK-KS Ag, and (iv) LAK-KS Ag allows for cold-target inhibition between different KS cells. The identification of LAK-KS Ag and a monoclonal antibody capable of inhibiting lysis of ECs and M phi without obstructing LAK-KS Ag would be important.

Factor-XIIIa-expressing dermal dendrocytes in Kaposi's sarcoma

The histogenetic origin of Kaposi's sarcoma is a matter of controversy, with recent reports claiming it to derive from the factor-XIIIa-positive dermal dendrocyte rather than endothelial cells. We investigated the potential role of factor-XIIIa-positive dermal dendrocytes in the genesis of both classical (endemic) and immunosuppression-associated Kaposi's sarcoma. Thirteen cases of classical and 16 cases of immunosuppression (mostly AIDS)-associated Kaposi's sarcoma were immunostained with antibodies to factor XIIIa and to the blood-group antigen H, recognizing endothelial cells. Factor-XIIIa-positive cells were consistently antigen-H-negative and represented only a small percentage (usually less than 10%) of the proliferative cells. Their relative density tended to be decreased in immunosuppression-associated Kaposi's sarcoma when compared with that of the classical form. These results do not support the view that dermal dendrocytes may be the cells of origin of Kaposi's sarcoma; conversely, their decreased density in cases of immunosuppression-associated Kaposi's sarcoma could be related to immunosuppression and may account for more rapid tumour growth.

Chylous ascites in Kaposi's sarcoma: a case report

We report a case of a patient with Kaposi's sarcoma (KS), massive chylous ascites and chylous pleural effusions. This association has not been reported previously. The pathogenesis of chylous effusions is discussed with respect to KS.

Cytomegalovirus vasculitis accompanied by an exuberant fibroblastic reaction in the intestine of an AIDS patient

A case of cytomegalovirus (CMV) vasculitis in the intestine of a patient with acquired immune deficiency syndrome (AIDS) is reported. The distal jejunum and ileum had multiple well-demarcated mucosal ulcers and microscopic examination revealed an unusual, exuberant fibroblastic proliferation in the ulcer base. Amidst these fibroblasts, there were several small blood vessels of which the endothelial cells contained cytomegalic inclusion bodies. The lesion showed a Kaposi's sarcoma-like appearance, but spindle cells were negative in immunostaining for factor VIII-related antigen or Ulex europaeus agglutinin-1. Although the CMV infection was observed in almost all organs, the exuberant fibroblastic proliferation seen in the intestine was not found in other organs. This lesion might represent a peculiar reaction of the immunologically compromised host to the CMV in the intestinal blood vessels.

HIV-associated Kaposi's sarcoma: new developments in epidemiology and molecular pathology

New epidemiological data give evidence for an unknown etiological agent of Kaposi's sarcoma (KS). Experimental support is provided by research on cultivated KS cells. These results contradict a direct involvement of HIV-1 in the pathogenesis of KS. Research on cultivated KS cells confirmed the hypothesis that KS spindle cells originate from endothelial cells and gave new insight into the pathogenesis of tumor cell growth. KS spindle cells secrete an autocrine acting growth promoting activity. Nevertheless, they seem to depend on several growth factors like PDGF and IL-6 provided by surrounding endothelial cells and macrophages, respectively. The results support the hypothesis of a tumor relying on paracrine acting factors more than on autocrine acting factors.

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.

HIV infection of human gastrointestinal submucosal cells: an in vitro model that mimics Kaposi's sarcoma

Infection of human gastrointestinal submucosal mesenchymal cells with HIV-1 led to cell populations with abnormal growth properties, increased synthesis of endothelial cell and angioblast markers, and release of angiogenic factors. This system may be the first in vitro model for HIV-induced Kaposi's sarcoma.

Evaluation of spindle cell tumors

The most important aspect of any evaluation of spindle cell tumors in the skin or superficial soft tissues is the clinical examination, as a great deal can be learned from the location, appearance, and size of the tumor in question. As recounted in this chapter, the histologic features of these tumors may also be distinctive; however, in some instances, histologic examination alone is insufficient for diagnosis. In such cases, electron microscopy holds considerable promise, but the technique is too dependent upon both the availability of adequately preserved tissues and access to the technique itself. As a result, immunohistochemistry remains the favored approach to most problematic lesions. In our experience, at least 90% of histologically enigmatic tumors will exhibit a characteristic immunophenotype, the remainder usually being indeterminant for a specific pattern of differentiation. The latter outcome is often the result of improper tissue preservation, but may also reflect the primitive nature of some neoplasms. Fortunately, the least common outcome is an ambiguous or "mixed-lineage" phenotype, in which neither one of two or more patterns of differentiation is resolved with certainty. The most common settings in which these problems arise are the separation of MPNST from LMS, and the recognition of melanocytic lesions as distinct from tumors of peripheral nerve sheath. The latter is clearly of greatest clinical concern, and should be the focus of additional study.

Endemic Kaposi's sarcoma in human immunodeficiency virus type 1-seronegative persons: demonstration of retrovirus-like particles in cutaneous lesions

In 1984, Greek physicians reported on the clustering of cases of Kaposi's sarcoma (KS) on the Peloponnesus peninsula. To gain more insight into its pathogenesis, we studied the seroepidemiologic and clinicopathologic characteristics of 12 Greek KS patients (eight male/four female) five of whom were residents of an endemic area on the Peloponnesus. These patients were in good general health with ages ranging from 48 to 80 years, had no clinical signs of immunodeficiency, and combined the features of both classic and epidemic KS in that they displayed not only involvement of acral areas but also widespread mucocutaneous lesions. Routine laboratory data were within normal limits; no patient had HTLV-1 and HIV-1/2 antibodies, but all patients had antibodies to several herpesviruses. The histopathology was characteristic of KS with the peculiar feature of a dense infiltrate composed predominantly of CD4+ T lymphocytes. Immunoenzymatic/morphologic studies of the KS cells were consistent with their origin from lymphatic endothelium. Outstanding ultrastructural findings were tubuloreticular structures and cylindrical confronting cisternae, structures that are indicative of an ongoing viral infection. Indeed, extensive electronmicroscopic studies resulted in the detection of retrovirus-like particles in close association to KS cells in five of 12 patients. This in situ observation opens the possibility that this retro-virus contributes to KS development.

JC70: a new monoclonal antibody that detects vascular endothelium associated antigen on routinely processed tissue sections

A new monoclonal antibody, JC70, raised against a membrane preparation from a spleen affected by hairy cell leukaemia, recognises a membrane bound glycoprotein identical with that of the CD31 group of monoclonal antibodies. The antibody stains a fixation resistant epitope on endothelial cells in benign and malignant conditions in a wide variety of paraffin wax embedded tissue. JC70 stained malignant endothelial cells in 10 angiosarcomas with more consistency than monoclonal or polyclonal antibodies to factor VIII related antigen (FVIII-Rag). In four cases of Kaposi's sarcoma the antibody stained malignant endothelial cells but not spindle cells. It is concluded that antibody JC70 is of value for studying benign and malignant human vascular disorders in routinely processed tissue.

Benign lymphangioendothelioma

We have studied eight cases of an acquired lymphatic endothelial lesion for which we propose the name "benign lymphangioendothelioma." The lesions developed as solitary, slowly extending, erythematous macules and plaques, usually occurring on the extremities or the shoulders in adolescents or adults. The characteristic histopathologic feature is permeation of the dermal collagen by flattened, endothelium-lined channels and spaces. Hemorrhage, iron deposition, and inflammation were not part of the lesion. Ulex europaeus agglutinin I labeled the lesional endothelial cells consistently, but factor VIII-related antigen labeling was negative. This histologic pattern and the special studies suggested a lymphatic lesion. Surgical excision, performed in six patients, was not followed by recurrence.

Inflammatory pseudotumor of lymph nodes. Immunohistochemical evidence for its fibrohistiocytic nature

Five cases of inflammatory pseudotumor (IPT) of the lymph node were investigated by means of light microscopy and immunohistochemistry to elucidate its cellular composition. The IPT is composed of a proliferation of spindle cells, inflammatory cells, and small vessels, forming high and poor cellular areas. Many spindle cells correspond to activated histiocytes as they coexpress vimentin and macrophage-associated markers; they are intermingled with vimentin-positive fibroblasts and variable numbers of vimentin- and actin-positive myofibroblasts. This mixed-cell proliferation invades and/or destroys medium- and large-sized vessels in all cases. This study indicates that the spindle cell proliferation, identified as histiocytic and fibroblastic in nature, represents the main component of the nodal IPT. We speculate that release of cytokines by the activated histiocytes may result in the development of the complex histopathologic aspects of this inflammatory process and, if inappropriate, may represent the underlying pathogenic mechanism.

QBEnd/10: a new immunostain for the routine diagnosis of Kaposi's sarcoma

Kaposi's sarcomas are seen more commonly in routine histopathology laboratories since the advent of the more widespread and aggressive variant of the disease associated with HIV infection. Distinguishing nodular lesions from other spindle cell and vascular tumours can sometimes be difficult. Immunohistochemistry has been disappointing as a diagnostic aid, often requiring special fixation or frozen tissue and even then, staining of spindle cells has been variable. We describe the use of the new IgG1 mouse monoclonal antibody raised against human placental endothelial cells, QBEnd/10, on routine formalin-fixed, paraffin-embedded tissue. A retrospective study was performed on 22 Kaposi's sarcomas of skin including patch, plaque, and nodular lesions and compared with 38 other vascular and spindle cell tumours from skin. All sections were stained with haematoxylin and eosin, QBEnd/10, Ulex europaeus agglutinin 1 (UEA-1) and for factor VIII-related antigen (FVIIIRAg). The results demonstrate that spindle cells in lesions from Kaposi's sarcomas, but not other vascular or spindle cell tumours, immunostain clearly with QBEnd/10. Immunostaining for FVIIIRAg shows only weak and irregular positivity of the spindle cells, whilst staining with UEA-1 is consistently negative. We find that immunostaining with QBEnd/10 aids the diagnosis of Kaposi's sarcomas and allows their distinction from other spindle cell neoplasms of skin in routinely processed material.

Irradiation-induced penile angiosarcoma

We report a case of angiosarcoma of the glans penis in a 77 year old male Caucasian. The tumour developed 18 years after a course of radiotherapy for a penile ulcer which was an intra-epidermal squamous carcinoma. The differential diagnosis and the concept of radiotherapy-induced angiosarcomas are discussed.

Multinucleate cell angiohistiocytoma: an acquired vascular anomaly to be distinguished from Kaposi's sarcoma

Multinucleate cell angiohistocytoma is a newly described benign vascular condition that usually arises on the extremities of women over the age of 40 as discrete grouped violaceous erythematous papules, often mimicking Kaposi's sarcoma. Of 10 patients, nine were women aged between 37-66 (average 51.5) years at the onset of their condition. The legs, and in particular the calves and thighs, were the commonest sites to be involved. However, in three patients the papules were confined to the back of the hands, and the male patient had lesions across the front of the chest. Bilateral lesions occurred in four patients. Histologically, the salient features were proliferation of capillaries and small venules at the level of the subpapillary plexus and the mid dermis, in association with prominent connective tissue cells and larger angulated multinucleate cells. Detailed histochemical and immunocytochemical studies have not elucidated the histogenesis of the multinucleate cells that seem to be a characteristic feature of this condition.

Some special skin tumours in the elderly

A review of uncommon skin tumours, all of which characteristically arise in elderly patients, is presented. Angiosarcoma of the face and scalp is a highly progressive tumour with a poor prognosis, but initially it may be misdiagnosed as a simple bruise or cellulitis. In well-differentiated tumours a characteristic feature is interlacing endothelial cell-lined channels showing considerable nuclear atypia. Merkel cell tumours, which develop as deep-seated nodules in the skin, occur most frequently in photodamaged areas, especially on the head and neck. The prognosis of Merkel cell tumours is generally poor; histological evidence suggests that some of these tumours may be a special type of poorly differentiated squamous cell carcinoma. Atypical fibroxanthoma, which is normally benign, occurs most frequently in elderly, fair-skinned males, especially around the face. It is typically a polypoid lesion with a vascular appearance. Acantholytic squamous cell carcinomas, also known as adenoid squamous cell carcinomas, are most common in fair-skinned men with a history of keratoses. They also occur in the female genital region and the oral mucosa. Histologically, these tumours differ from squamous cell carcinomas because of their tendency to form duct-like areas in tumour lobules.

Kaposi's sarcoma in Colombia

Seventy-nine cases of Kaposi's sarcoma (KS), which correspond to one of every 1,000 malignant tumors, were reviewed at the National Institute of Cancer (NIC), Bogotá, Colombia, from 1935 to 1985. Seventy-four percent of the patients were older than 65 years of age. The male to female ratio was 8:1. In all cases, plaques and nodules first appeared in the lower limbs; they were symmetrical in 47% of the cases and ulcerated in 25%. No generalized or epidemic forms were seen. Esophageal squamous cell carcinoma concurrent with KS was observed in one case. KS developed several years after treatment for follicular lymphoma and chronic lymphocytic leukemia in two patients. An angiosarcomatous variant and one fibrosarcomatous change were seen. Ten cases studied for factor VIII expression through the peroxidase-antiperoxidase (PAP) technique were all reactive. We conclude that in Colombia before 1985, KS behaved as a chronic multicentric Stage I disease without a tendency to associate simultaneously with malignant conditions.