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

Abstract

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.

Immunohistochemical Expression of Vascular Endothelial Growth Factor and Microvessel Counting as Prognostic Indicators in Node-Negative Colorectal Cancer

“…Both the proportion and density of VEGF-A expression were shown to be positively correlated with colon carcinogenesis [13] and it has been demonstrated that low levels of VEGF, as assessed by IHC, predicted for eventfree survival in node-negative colon cancer [14]. This confirms the previous work of a number of authors, including Takahashi et al [19], who showed that overexpression of VEGF and its receptor (KDR) predicted for metastasis.…”

Vascular Endothelial Growth Factor Receptor-3 (VEGFR-3): A Marker of Vascular Tumors with Presumed Lymphatic Differentiation, Including Kaposi's Sarcoma, Kaposiform and Dabska-Type Hemangioendotheliomas, and a Subset of Angiosarcomas

“…Our results strongly affirm the superb sensitivity of antibodies to VEGFR-3 for KS; the spindle cells in 24 of 25 cases of KS, at all stages of development and including metastatic lesions, were strongly positive for VEGFR-3. The sensitivity of anti-VEGFR-3 in paraffin-embedded sections (96%) compares very favorably to that reported for CD31 (89%) (5), CD34 (93%) (19), and vWF (64%) (20). Our findings of slightly greater sensitivity for CD31 (93%) and vWF (79%) may be the result of our uniform use of heat-induced epitope retrieval.…”

Different immunoreactivity of endothelial markers in well and poorly differentiated areas of angiosarcomas

“…The CD34 antigen, also known as human haematopoietic progenitor cell antigen, is a heavily glycosylated transmembrane protein expressed on immature human haematopoietic precursor cells from normal bone marrow, and in a significant number of acute leukaemias [3,4,6,21,23,41]. Several studies have demonstrated CD34 antigen expression in vascular endothelium [10, 33], and in endothelial derived tumours [20,39], especially Kaposi's sarcoma [11,19,28,33,34].…”