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Aims A wide range of post-radiotherapy (RT) vascular lesions can occur, ranging from benign lymphangiomatous papules of the skin (BLAPs), to atypical vascular lesions (AVLs) and post-RT angiosarcomas (ASs). The relationship between benign and malignant post-RT breast lesions and their prognostic features are still controversial. The aims of this study were to investigate the relationship between benign and malignant mammary post-RT vascular lesions and to define post-RT AS prognostic features. Methods and results Seventy-four post-RT vascular lesion cases were obtained and stained with antibodies against CD34, CD31, D2-40, Ki67, and c-Myc. Mutational analysis was performed by deep sequencing for the following genes: KRAS, NRAS, HRAS, BRAF, PIK3CA, TP53, NOTCH1, PTEN, CDKN2A, EGFR, AKT1, CTNNB1, hTERT, and PTPRB. Post-RT AS cases were graded according to a previously reported breast AS grading system. AVL cases showed a low number of HRAS and hTERT mutations, whereas post-RT AS cases showed a high frequency of EGFR, TP53, HRAS and hTERT mutations. On follow-up, all BLAP and AVL patients were alive with no evidence of disease. Post-RT AS 5-year overall survival declined with the increase in grade, as follows: 85.7% for grade 1, 83.3% for grade 2, and 40.4% for grade 3. Conclusions Our findings confirm that BLAP and AVL have a good prognosis, and that post-RT AS prognosis is strongly related to histological grading. On molecular analysis, AVL and post-RT AS shared HRAS and hTERT mutations, suggesting a relationship between the two lesions.

Aims Littoral cell angioma (LCA) is a rare primary splenic tumour that is frequently associated with internal malignancies. Immunohistochemistry can demonstrate a distinct hybrid endothelial–histiocytic phenotype of littoral cells, and is a helpful adjunct for making the correct diagnosis. The aims of this study were to present a series of 25 LCAs, with an emphasis on the frequent association of the neoplasm with visceral malignancies, and to provide a detailed immunohistochemical analysis by employing new markers. Methods and results All 25 cases with available tissue blocks were immunohistochemically stained for endothelial and histiocytic markers. Clinical and follow-up data were retrieved from the respective institutions. The tumours were obtained from 16 males and nine females, whose age ranged from 32 to 86 years (mean 56.2 years). Clinical information was available for 24 of 25 patients, and follow-up for 11 of 25 patients (range 2–19 years; mean 11.6 years). Immunohistochemically, all cases were positive for LYVE-1, factor VIII, FLI-1, vascular endothelial growth factor receptor (VEGFR)-2, VEGFR-3, claudin-5, ERG, LMO2, CD31, CD163, lysozyme, and CD4, but negative for D2-40, CD8, and factor XIIIa. Fifteen of 25 cases were associated with various malignancies, including epithelial, mesenchymal and haematological tumours. Conclusions The cohort of 25 patients is the largest series of LCAs published to date. By using antibodies against recently introduced endothelial markers, we have expanded the immunoprofile of LCA. We have further highlighted the clinical significance of LCA, as more than half of the patients in this study also harboured a coexisting visceral malignancy. Therefore, we conclude that the finding of splenic LCA mandates a thorough clinical evaluation for a concomitant malignancy.

Aims Programmed cell death-ligand 1 (PD-L1) expression is observed in patients with high level microsatellite instability (MSI-H) colon cancer, which is susceptible to immune checkpoint blockade. The aim of this study was to investigate the interrelationship between PD-L1-positive cells and cytotoxic T cells, lymphatic vessels, and vascular endothelium using histological examination with the three-dimensional (3D) reconstruction of a PD-L1-positive colon cancer. Methods and results Serial sections of MSI-H colon cancer tissue were stained with haematoxylin and eosin (HE PD-L1, CD8, D2-40, and CD31 immunohistochemistry were performed. Several 3D models of MSI-H colon cancer were reconstructed using a 3D data visualisation system. Moreover, 18 serial sections were stained with PD-L1, cytokeratin AE1/AE3, CD45, CD31, CD68, and H&E in the same case to confirm that PD-L1 was expressed on tumour cells, CD31-positive cells, and macrophages in the invasive frontal region. Notably, there was a peak in the expression of PD-L1 and CD31 in the invasive frontal region. D2-40-positive cells were abundant in the overall tumour stroma, and CD8-positive cells infiltrated the tumour parenchyma. PD-L1 was expressed on tumour cells in the parenchyma and other cells in the stroma. Additional staining of 18 consecutive sections revealed that the other cells were CD68- and CD45-positive macrophages and CD31-positive proliferating vascular endothelial cells. Conclusions We confirmed that PD-L1 was highly expressed in the invasive frontal region in 3D models of MSI-H colon cancer tissue. This method can be useful to accurately evaluate localisation of immune checkpoint molecules. This article is protected by copyright. All rights reserved.

Aims Extravascular migratory metastasis (EVMM) is a potential mechanism of tumour spread reported most extensively in cutaneous melanoma. It has not been described previously in gynaecological malignancies. We describe EVMM in four gynaecological carcinosarcomas. Methods and results Extravascular migratory metastasis was observed in an ovarian carcinosarcoma during routine diagnostic assessment. Twenty-three additional, randomly selected gynaecological carcinosarcomas (11 tubo-ovarian and 12 endometrial) were examined retrospectively and EVMM was identified in three of these. Other than the index case, EVMM was a focal finding, identified in 12–18% of slides. The malignant cells demonstrating EVMM appeared sarcomatoid and were distributed abluminally, partly or completely surrounding the endothelium. Affected vessels often showed mural fibrin deposition. Immunohistochemistry for α-smooth muscle actin (SMA), CD31, CD34, D2-40, laminin and type IV collagen was performed on the EVMM-positive cases. The perivascular malignant cells showed more consistent SMA and laminin immunoreactivity than the non-vascular tumour elements. Conclusions Extravascular migratory metastasis is a hitherto unrecognized mechanism of tumour spread in gynaecological carcinosarcomas. The perivascular tumour cells appear to adopt a pericytic phenotype, and this may represent a specific pattern of epithelial–mesenchymal transition. Further studies with pericyte-specific immunohistological markers may better demonstrate the presence and possible prognostic significance of EVMM in gynaecological tumours.

Aims: Mesenchymal neoplasms of the kidney are rare, and most represent sporadic angiomyolipomas. A few haemangiomas have been reported in end-stage renal disease (ESRD) but, to date, no study has focused on the frequency and morphological spectrum of mesenchymal lesions in ESRD. Methods and results: We evaluated retrospectively 90 nephrectomy specimens with ESRD. Haemangiomas were detected in eight cases (8.8%; six males and two females; mean age: 55 years); four were multifocal and four had concurrent renal epithelial neoplasms. Lesions involved the medulla (three), cortex (two) or both (three), and the size range was 1–25 mm (mean 4.8 mm). Histologically, all were capillary haemangiomas with an at least focally detectable spleen-like anastomosing pattern. All tumours stained positively for CD31 and FLI-1, but none expressed pankeratin (KL-1), podoplanin/D2-40, HHV8 or GLUT-1. Minute angiomyolipomas (mean size 2.3 mm) were detected in four patients (mean age 49.5 years). Tumour-like smooth muscle proliferations were seen surrounding muscular arteries (eight), occasionally admixed with fat extending from the renal sinus mimicking angiomyolipoma. No similar tumours were found in 105 control kidneys. Conclusions: Benign haemangiomas are not uncommon in ESRD, but may be under-recognized. They display distinctive morphology and should be distinguished from angiosarcomas and capillary-rich renal cell carcinomas.

Sheng W Q & Wang J (2012) Histopathology Primary pseudomyogenic haemangioendothelioma of bone Aims: Pseudomyogenic haemangioendothelioma is a recently described vascular neoplasm that occurs most commonly in the soft tissue of distal extremities of young adults. Occurrence outside the somatic soft tissue has not been described thus far. We present here a unique case of pseudomyogenic haemangioendothelioma that arose in the long tubular bones of the lower extremity. Methods and results: The initial open biopsy was interpreted as a fibrous histiocytoma. However, the curettage specimen showed prominent epithelioid cytomorphology with a striking rhabdomyoblast-like appearance. By immunohistochemistry, the linear membranous staining of CD31 was highly suggestive of endothelial differentiation of the tumour cells. Conclusions: To the best of our knowledge, this case represents the first example of primary pseudomyogenic haemangioendothelioma of bone. Clinical and pathological correlation with application of immunohistochemistry is mandatory in establishing the correct diagnosis and excluding tumours with overlapping features.

Battistella M, Guedj N, Fallet-Bianco C, Bodemer C, Brousse N & Fraitag S (2011) Histopathology59, 407–420 The histopathological spectrum of cutaneous meningeal heterotopias: clues and pitfalls Aims: To describe the histopathological features of heterotopic cutaneous meningeal tissue. Methods and results: Nineteen cases were collected between 1993 and 2010. Immunohistochemistry for epithelial membrane antigen (EMA), neuron specific enolase (NSE), S100, glial fibrillary acid protein (GFAP), progesterone receptor (PR), CD31, glucose transporter-1 (Glut-1), podoplanin and NKI-C3 was performed. Lesions were congenital (100%) and presented as aplasia cutis with alopecia (63%) or lumps (37%), on the scalp (18 of 19) and sacral region. Resonance magnetic imaging revealed four underlying anomalies of the neuraxis. Histopathological analysis showed meningeal tissue arranged in four variably associated architectural patterns: fibrous (100%), pseudovascular (100%), cellular (68%) and pseudomyxoid (32%). Other features included collagen bodies (58%), calcifications (26%) and dermal melanocytes (32%). Heterotopic brain tissue or heterotopic ependymal cyst was associated in two cases. Arachnoidal cells expressed EMA and NSE, but not S100 protein, CD31 or GFAP. They expressed podoplanin (93%), especially in pseudovascular areas, NKI-C3 (79%), and less frequently Glut-1 (46%) and PR (30%). Conclusions: Histopathological features of cutaneous meningeal heterotopias are various and sometimes misleading. Fibrous lesions should not be misdiagnosed as aplasia cutis. Podoplanin-positive pseudovascular spaces represent the main pitfall and should not be diagnosed as lymphangioma. Correct diagnosis is confirmed by EMA and NSE coexpression within the lesion.

Aims: To determine the contributions of mast cells (MC), eosinophil leucocytes (EL) and microvessel den-sity (MVD) in lip carcinogenesis, and to establish the relationships between these biomarkers and their possible prognostic value in lip squamous cell carci-noma (LSCC). Methods and results: Archived specimens of lip mucosa (n= 13), actinic cheilitis (n= 29) and LSCC (n= 29) were formalin-fixed, paraffin-embedded, sectioned and stained with toluidine blue and haematoxylin and eosin (H&E) in order to identify MC and EL and to measure their densities. Tumour angiogenesis was estimated by determining, with the use of CD31 antibody MVD in areas with the highest number of stained microvessels (‘hot spots’). Progressive increases of MC, EL and MVD were observed during lip tumour development. Correla-tion analysis revealed positive associations between the biomarkers during tumour progression. In LSCC sam-ples, significant associations were found between MVD values and metastatic disease. On multivariate analysis, MVD was a predictor of risk of cervical metastasis. Conclusions: The densities of MC, EL and microvessels increase during lip carcinogenesis, and for MC and EL this may be related to the stimulation of tumour angiogenesis. MVD could be a useful predictor of cervical metastasis in LSCC

Ferlicot S, Vernochet A, Romana S, Ortin-Serrano M, Letierce A, Bregerie O, Durrbach A & Guettier C (2010) Histopathology56, 188–197 Microchimerism in renal allografts: clinicopathological associations according to the type of chimeric cells Aims: Recent studies have highlighted the presence of microchimerism in various solid allografts. The biological significance of these chimeric cells is controversial. They may be beneficial, leading to better tolerance of grafts or participating in tissue repair or, in contrast, deleterious if involved in chronic lesions. The aim was to assess the frequency and cellular nature of microchimerism in female renal grafts of male recipients by combined fluorescence in situ hybridization (FISH) for Y chromosome and immunohistochemistry and to investigate associations between intragraft microchimerism and histological lesions or allograft outcome. Methods and results: We screened 33 renal biopsy specimens, including 11 with acute T-cell-mediated rejection and nine with transplant glomerulopathy, from 22 male recipients transplanted with female kidneys by FISH and immunohistochemistry with antibodies against smooth muscle actin (mesangial cells), CD31 (endothelial cells), KL1 (epithelial cells), CD45 (leucocyte common antigen) and glomerular epithelial protein 1 (podocytes). Tubular microchimerism was detected in 71% of the patients with a mean percentage of chimeric epithelial cells of 1.4%. Glomerular microchimerism involving podocytes, mesangial and endothelial cells was present with a mean number of chimeric cells per glomerular section of, respectively, 0.6, 2.66 and 3.53. There was an association between endothelial microchimerism and a previous episode of acute T-cell-mediated rejection. Conclusions: In conclusion, microchimerism in renal grafts occurs frequently, but at a low level and affects tubular cells and all glomerular cell compartments in human renal allografts.

Aims Vascular invasion is a prognostic marker for many cancers, including endometrial carcinoma. Immunohistochemistry using D2-40 and CD31 antibodies makes it possible to differentiate between lymphatic vascular invasion (LVI) and blood vessel invasion (BVI). The aim was to examine lymphatic and blood vessel invasion separately and their associations with clinicopathological characteristics and prognosis. Methods and results Immunohistochemistry was performed on a retrospective population-based series of endometrial carcinoma. Altogether, 31% of the 276 tumours showed lymphatic involvement, whereas 18% showed blood vessel invasion. LVI and BVI were associated with histopathological variables such as histological grade and tumour growth pattern. Patients without vascular invasion had the best prognosis and those with BVI (with or without LVI) had the worst outcome, whereas patients with LVI had an intermediate survival on univariate analysis. Multivariate models indicated that both LVI and especially BVI had independent prognostic importance. Among endometrioid carcinomas, BVI was still significant. Conclusions Our findings support the biological importance of vascular spread through the haematogenic and lymphatic routes in endometrial cancer. The significant correlation found with clinical phenotype indicates that these markers may be relevant for patient management.

Sinusoids are found not only in the normal liver but also in certain liver tumours, including hepatoblastoma, the most common malignant liver tumour in childhood. In this study, sinusoids in 12 hepatoblastomas, of various subtypes, and in normal liver were investigated with UEA-1 and antibodies against von Willebrand's factor, CD31 and CD34 to detect differences of possible diagnostic significance. In the normal liver, staining of sinusoids was seen with all these markers, but it was focal and confined to a few sinusoids near the portal tracts. In hepatoblastoma, the endothelial markers reacted with the sinusoids to varying extents. UEA-1 and anti-CD34 usually stained the majority of these vessels, anti-CD34 staining greater numbers of sinusoids and with greater intensity. Immunostaining revealed that both number and spatial organization of sinusoids in hepatoblastoma are dependent on the subtype. In addition to staining of endothelium, one of the two small cell hepatoblastomas exhibited strong immunoreactivity of the tumour cells for CD34. These findings show that the marked difference in sinusoidal immunoreactivity for CD34 between normal liver and hepatoblastoma could be useful for discriminating between non-neoplastic liver tissue and highly differentiated fetal hepatoblastoma. Our findings also show that small cell hepatoblastoma, in addition to acute leukaemia, should be considered when immunoreactivity for CD34 is found in small round and blue cell tumours in childhood.

Aims Male sex is a risk factor for medulloblastoma (MB), and is also a negative predictor for clinical outcome. The aim of this study was to assess sex differences in tumour biological features and hormone receptor profiles in a cohort of MB patients. Methods and results Sixty-four MBs and five normal cerebella were included in the study. Cell proliferation (Ki67), apoptosis (cleaved caspase-3) and microvessel density (CD31) were evaluated in tumours by immunohistochemistry. Tissues were analysed for oestrogen receptor (ER)α, ERβ1, ERβ2, ERβ5 and androgen receptor (AR) expression. The results demonstrated sex-specific features in MBs, with tumours from females showing a higher apoptosis/proliferation ratio and less tumour vascularization than tumours from males. MBs were negative for ERα and AR, but expressed ERβ isoforms at similar levels between the sexes. Altogether, these findings indicate that signalling mechanisms that control cell turnover and angiogenesis operate more efficiently in females than in males. The lack of sex differences in the hormone receptor profiles suggests that circulating oestrogens could be the major determinants of the sexual dimorphism observed in MB features. Conclusions Here, we provide molecular support for epidemiological data showing sex differences in MB incidence and outcome, completely defining the hormone receptor profile of the tumours.

Evaluation of perineurial differentiation in epithelioid sarcoma Aims: To investigate the differentiation pattern of epithelioid sarcoma in terms of perineurial and endothelial differentiation, and its relationship to that of meningioma. Methods and results: Nine cases of epithelioid sarcoma and five cases of meningioma were studied in an immunohistochemical analysis of 'perineurial' antigens [GLUT-1, claudin-1, epithelial membrane antigen (EMA) and VE-cadherin] and of 'endothelial' antigens not present on normal perineurium (CD34, CD31, Fli-1). Both epithelioid sarcoma and meningioma showed frequent expression of the perineurial markers GLUT-1, claudin-1 and EMA. VE-cadherin was identified in one of five meningiomas, and in the only case of epithelioid sarcoma in which suitably fixed material was available. CD34 was expressed by all epithelioid sarcomas studied but by none of the meningiomas. Fli-1 was present in a substantial majority of epithelioid sarcomas and by all the meningiomas. CD31 was not detected in any epithelioid sarcoma or meningioma. Conclusions: The results were evaluated in the context of previous immunohistochemical, ultrastructural and genetic studies and suggest that epithelioid sarcoma may be a form of malignant perineurioma with a range of differentiation (epithelial features) akin to that seen in meningioma, reflecting the close relationship between perineurium and meningothelium.

Aims : Two-hundred and four accessible cases of malignant melanoma from the Grampian region of Scotland, collected over a period of 4 years, were studied for standard prognostic indicators for comparison with microvessel density. Methods and results : The range of tumour thickness varied from in-situ melanoma to 14.8 mm. Microvessel density was assessed using the Chalkley technique on sections immunostained with CD31 antibody to identify endothelium. Vessel counts were performed in the peritumoral host tissue of all specimens. Strong correlation was observed between microvessel density at the tumour edge and tumour thickness (P

Aims : To evaluate the expression of D2-40 in normal lymphatic endothelium and vascular tumours or tumour-like lesions of the skin and soft tissue. D2-40 is a novel monoclonal antibody to a Mr 40 000 O-linked sialoglycoprotein that reacts with a fixation-resistant epitope in lymphatic endothelium. Methods and results : Formalin-fixed paraffin-embedded sections from 30 normal tissue samples, including skin, soft tissue, stomach, and colon, and 84 vascular tumours or vascular tumour-like lesions were immunostained with monoclonal antibodies to D2-40 and CD31. Normal lymphatic endothelial cells in all normal tissues expressed D2-40. Its positive staining delineated flattened channels or open spaces lined by a single layer of endothelial cells whose lumena were sometimes filled with lymphocytes. Ten of 10 cases of lymphangioma, nine of 10 Kaposi's sarcomas (KSs), one of five spindle cell haemangiomas, one of one reactive angioenodotheliomatosis, one of one vascular transformation of lymph node sinuses, three of three Dabska tumours, one of 10 epithelioid haemangioendotheliomas (HEs) and seven of 15 angiosarcomas were positive for D2-40. Positively staining angiosarcomas were characterized by epithelioid or papillary endothelial cells. Twenty-two non-spindle cell haemangiomas, one retiform HE and one Kaposiform HE, and five glomus tumours were negative for D2-40. In comparison, CD31 was expressed in five of 10 lymphangiomas, nine of 10 KSs, 27 of 27 haemangiomas, three of three Dabska tumours, 10 of 10 epithelioid HEs, 15 of 15 angiosarcomas and one of one each of retiform HE, Kaposiform HE, reactive angioendotheliomatosis, and vascular transformation of node sinuses. Five glomus tumours were negative for CD31. Conclusions : The monoclonal antibody D2-40 is a highly sensitive and specific marker of lymphatic endothelium in normal tissue and a subset of vascular lesions, including KS, Dabska tumour, and lymphangioma. The findings support the concept that these tumours show at least partial lymphatic endothelial differentiation. Subsets of angiosarcomas and HEs show both vascular and lymphatic endothelial differentiation. D2-40 can be used in a panel of markers to classify vascular tumours. There is no requirement for epitope retrieval. This novel monoclonal antibody also has the potential for increasing the accuracy of detection of lymphatic invasion in primary tumours and could be widely applied for this purpose in surgical pathology.

Aims: Cyclooxygenase-2 (COX-2) and vascular endothelial growth factor (VEGF) are frequently up-regulated in malignant tumours and play a role in proliferation, apoptosis, angiogenesis and tumour invasion. In the present study, the expression of COX-2 and VEGF in renal cell carcinoma (RCC) was analysed and correlated with the microvessel density (MVD). Methods and results: COX-2 and VEGF were analysed by realtime reverse transcriptase-polymerase chain reaction and immunohistochemistry. The MVD was assessed by CD31 immunohistochemistry. The expression of COX-2 and VEGF was determined in the RCC cell lines A498 and Caki-1 under short-term hypoxia and in multicellular tumour cell aggregates. COX-2 was expressed in RCC by tumour epithelia, endothelia and macrophages in areas of cystic tumour regression and tumour necrosis. COX-2 protein in RCC was not altered in comparison with normal renal tissue. VEGF mRNA was up-regulated in RCC and positively correlated with MVD. RCC with high up-regulation of VEGF mRNA showed weak intracytoplasmic expression of VEGF in tumour cells. Intracytoplasmic VEGF protein expression was negatively correlated with MVD. In RCC with necrosis the MVD was reduced in comparison with RCC without necrosis. A498 RCC cells down-regulated COX-2 and up-regulated VEGF under conditions of hypoxia. In Caki-1 cells COX-2 expression remained stable, whereas VEGF was significantly up-regulated. In multicellular A498 cell aggregates COX-2 and VEGF were up-regulated centrally, whereas no gradient was found in Caki-1 cells. Conclusions: COX-2 and VEGF are potential therapeutic targets because COX-2 and VEGF are expressed in RCC and associated cell populations such as endothelia and monocytes/macrophages.

Aims: To describe five malignant tumours in the breast (two invasive carcinomas and three non-Hodgkin's lymphomas) showing an unusual pattern of spread within anastomosing spaces consistent with those described in pseudoangiomatous stromal hyperplasia. Methods and results: The histological and immunohistochemical features of the cases are presented. In all cases, the neoplasms consisted of non-cohesive E-cadherin-negative cells located within anastomosing vascular-like channels. These channels showed morphological and immunohistochemical features consistent with those seen in pseudoangiomatous stromal hyperplasia: they were lined by flattened cells that expressed CD34, bcl2 and smooth muscle actin, while CD31 was consistently negative. Conclusions: The open channels of pseudoangiomatous stromal hyperplasia have been regarded as spaces due to loss of cohesiveness between stromal fibroblasts if not artefacts. The fact that neoplastic cells spread through these spaces suggests that the spaces are true open channels that may represent part of a complex network of stromal channels (pre-lymphatics) connected to the main lymphatic system of the breast. This finding opens new insights into the routes of tumour spread.

Aims Unusual cytoplasmic alterations have recently been reported in poorly differentiated cutaneous angiosarcoma, making an accurate diagnosis challenging. As these tumours remain poorly documented, we aimed to study their clinicopathological characteristics more comprehensively. Methods and results Six cutaneous angiosarcomas with unusual cytoplasmic alterations were identified from referral files. All tumours arose as nodules or plaques (range: 05–195 mm) on sun-damaged skin of the head and neck of elderly males (median age: 76.5 years). Histologically, the tumours were composed of enlarged epithelioid cells showing prominent signet ring (n = 3), foam (n = 2) or granular cell (n = 1) change. Vasoformative elements were only focally noted. By immunohistochemistry, all tumours expressed CD31 and avian v-ets erythroblastosis virus E26 oncogene homologue (ERG). Foam cell change was associated with additional expression of CD68 and CD163. Follow-up (median: 8 months) showed death from disease (n = 1), death from a gastrointestinal bleed (n = 1), and a cutaneous metastasis (n = 1). Only two patients are alive with no evidence of disease. Conclusions Our findings outline the morphological spectrum of cytoplasmic change in cutaneous angiosarcoma. Awareness and a high degree of suspicion in the context of tumours affecting sun-damaged skin of the elderly are necessary to direct appropriate immunohistochemical work-up with inclusion of the endothelial cell markers CD31 and ERG.

Aims: UK faecal occult blood test screening has tripled the proportion of pT1 colorectal cancers. The risk of metastasis is predicted by depth of invasion, suggesting that access to deep lymphovascular vessels is important. The aim of this study was to quantify the distribution and size of the submucosal vasculature, and generate a novel three-dimensional (3D) model to validate the findings. Methods and results: Thirty samples of normal large bowel wall were immunostained with CD31, a vascular endothelium marker, to identify blood vessels, which were quantified and digitally analysed for their number, circumference, area and diameter in the deep mucosa and submucosa (Sm1, Sm2, and Sm3). The model required serial sections, a double immunostain (using CD31 and D2-40), and 3D reconstruction. Significant differences were shown between submucosal layers in the number, circumference and area of vessels (P < 0.001). Blood vessels were most numerous in the mucosa (11.79 vessels/0.2 mm2) but smaller [median area of 247 μm2, interquartile range (IQR) 162–373 μm2] than in Sm2, where they were fewer in number (6.92 vessels/0.2 mm2) but considerably larger (2086 μm2, IQR 1007–4784 μm2). The 3D model generated novel observations on lymphovascular structures. Conclusions: The number and size of blood vessels do not increase with depth of submucosa, as hypothesized. The distribution of vessels suggests that we should investigate the area or volume of submucosal invasion rather than the depth.

Capsular intravascular endothelial hyperplasia: a peculiar form of vasoproliferative lesion associated with thyroid carcinoma Aims: Florid vasoproliferative processes are uncommon in the thyroid gland. We report three cases of an unusual vasoproliferation involving the capsular blood vessels of thyroid carcinoma. Methods and results: The histological diagnoses of the three cases were made on conventional histological sections. Two cases were minimally invasive follicular carcinomas and one case was an encapsulated variant of papillary carcinoma. Some blood vessels in the tumour fibrous capsule were filled with spindly cellular proliferations forming irregular vascular clefts and papillae. Immunohistochemical studies for CD31, CD34 and muscle-specific actin confirmed that the spindly cells were mostly endothelial cells variably supported by pericytes. Conclusion: This peculiar intravascular endothelial hyperplasia by itself should not be mistaken for vascular invasion by tumour, but evidence of malignancy must be diligently sought by extensive sampling because the lesion has thus far been consistently associated with malignant thyroid neoplasms.

Aims To determinate the relationship between tumoral angiogenesis and cathepsin D (CD) expression in tumour and host stromal cells of invasive breast carcinoma, and to examine its association with classical prognostic factors such as lymph node status, histological grade, tumour size, mitotic rate, peritumoral lymphovascular invasion and oestrogen receptor (ER) status. Methods and results Sections from 102 invasive breast carcinoma were cut from the archival formalin-fixed, paraffin-embedded tissue blocks and stained using immunohistochemistry for the endothelial cell adhesion molecule (CD31) and CD. Microvessel density was assessed by counting vessels in the three most vascular areas at × 400 field. The counts were expressed as the highest counts within any × 400 field. The evaluation of immunostaining for CD was performed separately in both the parenchymal and stromal cells. Microvessel density was correlated positively with histological grade and peritumoral lymphovascular invasion, and correlated inversely with ER status. Positive CD staining of tumour cells was more frequent in positive ER tumours and was not significantly associated with the other classical prognostic factors. However, moderate to strong staining of host cells was correlated with higher histological grade, higher mitotic index and lack of ER protein. There was a statistically significant association between CD expression of host stromal cells and higher vessel count. Conclusions CD in host stromal cells is associated with more aggressive tumours and with a higher intratumoral microvessel density. Evaluation of CD in combination with angiogenic activity may be of some help in more accurately predicting the biological behaviour of breast carcinoma.

Aims To evaluate the pattern of cadherin expression in epithelioid sarcoma. Methods and results Seven epithelioid sarcomas were immunostained by a polyclonal antibody that detects all cadherin subtypes and by monoclonal antibodies that detect epithelial cadherin (E-cadherin) and vascular-endothelial cadherin (VE cadherin). In addition, the tumours were immunostained for a variety of epithelial (cytokeratin, EMA, AUA1) and endothelial (Factor VIII-related antigen, CD34, CD31) markers. Tumour cells of all seven epithelioid sarcomas expressed cadherins. Surprisingly, E-cadherin was not detected in any of the sarcomas. VE-cadherin was detected in five of seven cases. All seven tumours expressed cytokeratins and EMA but none expressed AUA1. CD34 was detected in six of seven cases and CD31 was detected in a single case. No case expressed Factor VIII-related antigen. Conclusions Most epithelioid sarcomas strongly express cadherins, a feature which may contribute to their epithelioid appearance. The absence of detectable E-cadherin suggests that epithelial differentiation in these tumours is, at most, incomplete. The expression of VE-cadherin by the majority of cases, in the absence of E-cadherin, is consistent with an element of mesenchymal differentiation, possibly endothelial or perineurial. The additional presence of other markers such as CD34 and CD31 in some cases favours endothelial differentiation.

Aims Our aim was to determine the histogenesis of fibroid polyps (FP). These polyps are rare inflammatory-reactive, tumour-like lesions of unknown aetiology, arising in the submucosa or mucosa of the gastrointestinal tract. They are mainly due to a proliferation of characteristic spindle cells. Methods and results Nine FP were investigated by light microscopy and immunohistochemistry with endothelial markers (Factor VIII, CD34, CD31), a neuronal marker (S100), muscular markers (desmin, alpha-smooth muscle actin) and histiocytic markers (PGMI, KP1, MAC387) using the highly sensitive avidin–biotin–peroxidase technique. We demonstrate, for the first time, a consistent positivity of the characteristic spindle cells of FP for CD34. The proposed endothelial, histiocytic or neuronal origin of FP could be completely ruled out. Conclusions Because of the consistent positivity of the spindle cells of FP for CD34 we suggest an origin of these lesions from primitive perivascular or vascular cells. This origin and a probable relationship to gastrointestinal stromal tumours (GIST) is discussed.

Cardiac myxoma is an enigmatic tumour thought to arise from primitive cardiac mesenchymal cells. Factor XIIIa+ dendrophages are tissue histiocytes that are active in tissue repair and thrombosis. To explore whether factor XIIIa+ dendrophages play a role in cardiac myxoma morphogenesis, we stained four cases with an antiserum against coagulation factor XIIIa (FXIIIa). We also used antibodies recognizing CD34, CD31, and S-100 protein. Samples of valvular endocardium from 12 and 16 week fetuses and two adult autopsies were compared with the four myxomas. All cardiac myxomas had rounded and dendritic FXIIIa+ cells admixed with more numerous CD34+ spindle and stellate myxoma cells. The CD34+ cells formed multicellular syncytia and capillary sprouts. Many of these syncytial structures also expressed CD31 and, to a lesser extent, S-100 protein, strongly in two cases and more focally in two. Fetal subendocardium was composed of CD34+ stellate fibroblast-like cells invested with scattered FXIIIa+ histiocytes; no S-100+ cells were detected. Our findings confirm that cardiac myxomas are composed of CD34+ primitive subendocardial cells. These cells show a capacity for CD31+ endothelial differentiation. In cardiac myxoma, the CD34+ myxoma cells are accompanied by numerous FXIIIa+ dendrophages, the presence of which suggests abnormal organizing thrombus-like differentiation in cardiac myxoma morphogenesis.

Vascular endothelial cells are antigenically heterogeneous and therefore it has been recommended that a range of immunohistochemical markers is employed to show the presence of cells of endothelial origin in surgical pathology. In this study we applied three monoclonal antibodies--to factor VIII-related antigen, JC70 (CD31), QBend 10 (CD34)--and Ulex europaeus agglutinin type 1 lectin (UEA-1), to six consecutive cases of left atrial myxoma. We found that JC70 and QBend 10 consistently stained myxoma cells in all their different growth patterns contrasting with factor VIII-related antigen expression and UEA-1 binding which were restricted to areas which showed morphological evidence of vascular differentiation. These findings suggest that the constituent cells of atrial myxomas show more widespread endothelial differentiation than has previously been recognized and that differences in immunohistochemical staining may reflect the maturation status of these cells.

A case of endovascular papillary angioendothelioma-like tumour associated with lymphoedema is described. Microscopically, the tumour was composed of anastomosing vascular channels, some of which contained papillary projections, producing tuft-like or glomeruloid appearances. The dermis also showed moderate lymphoedema and lymphocytic infiltrate. The tumour resembled endovascular papillary angioendothelioma but also had several features that differed from typical examples: occurrence in an old patient and less prominent endothelial hobnail features and lymphocytic infiltrate. Three types of proliferating cells were observed: 1 mature flattened endothelial cells, which were strongly positive for endothelial markers (factor VIII-related antigen, CD31, CD34) and bound ulex europaeus agglutinin 1;2 immature endothelial cells with round nuclei and vacuolated or pale cytoplasm, which were strongly positive for CD31 and muscle-specific actin (HHF35) and focally positive for other endothelial markers; and 3 stromal spindle cells in papillary or glomeruloid areas, which were positive for vimentin, HHF35, and alpha-smooth muscle actin but negative for desmin. The tumour was diploid by flow cytometry. The patient was well without disease twelve months after the excision. We postulate that this tumour was caused by circulatory disturbance, namely lymphoedema associated with syringomyelia and a Charcot's joint.

The morphological and immunohistochemical features of a laryngeal angiosarcoma are described. Initially, the tumour was interpreted as a poorly differentiated squamous cell carcinoma. The laryngectomy specimen contained an extensive and haemorrhagic tumour consisting of irregular and dissecting vascular spaces delineated by pleomorphic endothelial cells. In addition to these obvious angiosarcomatous areas, islands of more compact growing tumour cells were present, reminiscent of a poorly differentiated squamous cell carcinoma. On immunohistochemistry, the tumour cells expressed factor VIII, Ulex europaeus I lectin, CD31 and vimentin. There was no expression of cytokeratin or epithelial membrane antigen. Angiosarcoma of the larynx is very rare and should be differentiated from a pseudo-angiosarcomatous carcinoma.

Four cases of cutaneous epithelioid angiosarcoma are described together with the potential diagnostic trap of mistaking these tumours for poorly differentiated carcinoma or malignant melanoma. The immunophenotypic profile using four endothelial markers showed positive staining in all cases for factor VIII related antigen in a predominantly paranuclear dot-like fashion and for CD31 (JC70); in three cases for CD34 (QB-END/10) and in two cases with UEA-1. All four cases were cytokeratin (CAM 5.2 and AE1/AE3) negative in contrast to the positive staining reported at non-cutaneous sites. Aberrant S-100 protein expression was seen in one case. In two cases subsequent recurrences showed better differentiation than the original tumour. Electronmicroscopy confirmed the absence of non-endothelial lines of differentiation but failed to reveal Weibel-Palade bodies.

Aims: The differential diagnosis of benign hepatic lesions and well-differentiated hepatocellular carcinomas can be a challenge, especially in small biopsy specimens. Recently, novel proteins expressed by the neovasculature in hepatocellular carcinoma (HCC) have been identified. The aim of this study was to compare the expression of podocalyxin-like protein 1 (PODXL1), a CD34-related sialomucin, in HCC and benign liver tumours or tumour-like lesions. Methods and results: Vascular marker expression was examined using tissue microarrays as well as standard paraffin sections from formalin fixed paraffin-embedded liver tissue samples. Expression of PODXL1 was compared with anti-CD34, CD31 and von Willebrand factor VIII staining by immunohistochemistry. PODXL1 is expressed in tumour-associated microvasculature endothelial cells in HCC, as well as in capillarized sinusoidal endothelium of focal nodular hyperplasia (FNH) and hepatic adenoma. Expression in cirrhotic nodules correlates with CD34 and highlights endothelium in the inflow area. In dysplastic nodules CD34 and PODXL1 are not or only focally expressed. Conclusions: Expression patterns of CD34 and PODXL1 are almost identical in primary hepatic tumours and tumour-like lesions. The presence of CD34+ and PODXL1+ sinusoidal endothelial cells aids in the diagnosis of HCC. Sinusoidal expression of PODXL1 is also seen in a less diffuse pattern in FNH and adenoma.

This paper reviews the histomorphological aspects of angiogenesis and neoangiogenesis, quantitative and qualitative, and their applications in prognostic evaluation of neoplastic diseases. The merits and weak points of intratumoral microvessel density (MVD), a widely regarded bona fide predictor of tumour growth, metastases and patient survival, are discussed. Total microvascular area (TVA) has been found useful in recent prognostic studies utilizing newer immunohistochemical vascular markers. Of particular significance is the fact that MVD and TVA are most predictive of patient outcome in those tumours that induce significant neoangiogenesis, namely carcinomas of breast and prostate, and haematological malignancies. In contrast, carcinomas of lung and urinary bladder do not show significant associations of MVD and TVA with poor prognosis, reflecting differences in angiogenic mechanisms. In gliomas, MVD appears to correlate with outcome in high-grade, but not low-grade tumours, and does not correlate with tumour cellularity in the infiltrating portions of the tumour, reflecting a paucity of neoangiogenesis and directional vascular growth. Recent studies have found CD105, Tie-2/Tek and vascular endothelial growth factor receptors to be the best markers of neoangiogenesis. The vascular parameters so measured correlate better with overall and disease-free survival in breast, colon and lung carcinoma than panendothelial markers such as CD31. A correlation of vascular patterns with prognosis has been established in ocular melanomas, glioblastomas and squamous carcinomas of head and neck region. Vascular networks with closed loops are closely associated with mortality due to metastases in uveal melanomas. Fewer bizarre glomeruloid vessels and prominent classical capillary pattern was an independent predictor of longer survival in glioblastoma. Therefore a judicious combination of quantitative and qualitative microscopic angiogenic parameters, with emphasis on neoangiogenesis and vascular patterns wherever applicable, should be an integral component of a more consistent tumour staging system for accurate prognostic evaluation of tumours, selection of optimal anti-angiogenic therapy and pertinent research.

Four endothelial cell markers, two selective cytokeratin markers and a monoclonal smooth muscle antibody (SMA) were employed in the assessment of 19 cases of cutaneous angiosarcoma classified according to their degree of tumour differentiation. No labelling was seen for SMA or with cytokeratin markers MNF116 and CBL170. Expression of factor VIII-related antigen was seen in two tumours and positivity for CD34 (QBend 10 antibody) was found in four tumours. By contrast the pan-endothelial cell marker Ulex europeaus agglutinin 1 (UEA-1) and the CD31 marker JC70A labelled all cases of cutaneous angiosarcoma with the exception of one poorly differentiated tumour. These data confirm the endothelial cell origin of angiosarcoma, they demonstrate that CD31 and UEA1 are reliable markers in routinely processed tissue, and they suggest a lymphatic derivation for the tumour. This finding is in marked contrast to Kaposi's sarcoma where CD34 is the most reliable marker.