Use the link below to share a full-text version of this article with your friends and colleagues. Learn more. To clarify the differences in angiogenesis between benign and malignant ovarian tumors, the authors examined the immunohistochemical characteristics and the density of tumor vessels in both tumor groups.
2. Neoplasia part 2: Differences between benign and malignant neoplasms
Intratumoral vascularization was observed preoperatively by transvaginal color Doppler ultrasound. The authors examined patients with ovarian tumors preoperatively for the presence or absence of intratumoral blood flow and evaluated the blood flow waveforms of tumor vessels in patients showing intratumoral vascularization, using a resistance index RI.
The characteristics of both smooth muscle and endothelial cells in the vessels of each tumor were immunohistochemically assessed, using monoclonal antibodies against smooth muscle actin SMA and CD34 an endothelial cell marker. Intratumoral blood flow was found in 64 of patients The tumors in 44 of these 64 patients were histopathologically benign, and the tumors in 20 were malignant.
The malignant tumors showed a low RI mean, 0. The vessels of malignant tumors significantly demonstrated poor SMA expression and intense CD34 expression compared with the vessels of benign tumors. However, no significant differences were observed in MVD between the benign and malignant tumors. In this study, immunohistochemical analysis demonstrated that low resistance to blood flow in vessels within malignant ovarian tumors may be associated with a poorly developed muscular coat in the tumor vessels, compared with that observed in benign tumors.
The difference in the angiogenic natures of benign and malignant ovarian tumors showing intratumoral blood flow may thus be correlated with the endothelial cell activity of the tumor vessels and not the MVD.
Recent studies have shown that color Doppler ultrasound CDU may be able to detect neovascularization in some solid tumors of the ovary, 1 endometrium, 2 breast, 3 , 4 and kidney. The authors' preliminary study also significantly demonstrated a low resistance to flow in tumor vessels within malignant ovarian tumors in comparison to that observed in benign ovarian tumors. Recently, many studies have shown that angiogenesis plays a key role in tumor growth and metastasis.
All patients were scanned in the lithotomy position with an empty urinary bladder within 3 days of surgery. Pregnant women with ovarian masses were excluded from this study.
The intratumoral blood flow, which depicted vascularization, was detected in 64 patients All patients underwent either laparotomy or laparoscopic surgery, and the benign or malignant nature of each ovarian tumor was confirmed by a postoperative histopathologic examination. However, 42 patients who did not show any intratumoral blood flow were excluded from this study because a Doppler examination could not be performed.
Benign and malignant tumours pdf
After visualizing the ovarian tumors, the blood flow velocity waveforms were recorded by placing the sample volume over the colored vessels and activating the pulsed Doppler.
The resistance index RI was calculated as the difference between the systolic and endodiastolic frequency shift divided by the systolic frequency shift. In premenopausal patients, the Doppler examinations were performed in the early to middle follicular phase during the menstrual cycle to avoid the effect of ovulation and the luteal blood flow. The authors determined the intraobserver coefficient of variation for the measurement of RI by performing 10 repeated measurements on 10 patients within 60 minutes.
The RI was thus determined to be 4. The sensitivity, specificity, and accuracy of the preoperative RI in detecting malignant ovarian tumors were determined when the cutoff value of the RI was set at 0. Moreover, in both benign and malignant tumors, a comparison of the mean RI value in each histopathologic type was made using the Student's t test for unpaired data.
What is Benign
The areas were chosen based on surgical specimens, which were obtained from the regions showing an intratumoral blood flow. The macroscopic features in each tumor first were compared with the sonographic features demonstrating an intratumoral blood flow photo preoperatively taken. The authors then searched for and marked the areas, which had been identified by a preoperative Doppler examination, within tumor.
The paraffin sections from each ovarian tumor were reacted with each primary antibody for 1 hour at room temperature in the authors' pathologic laboratory. Positive controls were sections from either adjacent benign tissue specimens or the contralateral normal ovary in each case. The density of smooth muscle cells, which was exhibited by SMA staining in tumor vessels of each tumor, was classified into four grades: high, moderate, poor, and absent, in comparison with each positive control by three observers in the pathologic laboratory.
Moreover, the SMA expression also was assessed by measuring the ratio of the tumor vessel count with a high or moderate density of SMA to the counts of all countable tumor vessels, per 0.
What is Malignant
The mean ratio in three sampling areas within the hypervascular fields in each tumor was determined and the obtained results were called the SMA expression index. Conversely, the intensity of CD34 expression for endothelial cells within the tumor vessels in each ovarian tumor was also classified into four grades: high, moderate, low, and negative, in comparison with each positive control.
The index was called the CD34 labeling index. Moreover, the average SMA expression index in benign and malignant ovarian tumors was calculated, respectively, and these were then compared, using the Student's t test for unpaired data.
What is the Difference Between Benign and Malignant
The average of CD34 intensity index in these tumors also was calculated and then compared in a similar manner to that of the SMA expression index.
The sections for the MVD analysis were chosen from the surgical specimens obtained from the color positive areas within each ovarian tumor. The quality of the staining was judged in comparison with normal blood vessels either in adjacent benign tissue or in the contralateral normal ovarian tissue. For the MVD quantitation, the authors modified the methods of Weidner et al.
In each section, the three most vascular areas were chosen. Large vessels with thick muscular walls and large vessels with lumina greater than approximately eight red blood cells were excluded from the count, as discussed by Bosari et al.
Intratumoral blood flow vascularization was preoperatively found in 64 of The most malignant ovarian tumors were found to have a rich intratumoral blood flow, in comparison with that observed in benign tumors Figs.
However, the three malignant tumors, which had shown no intratumoral blood flow, were comprised of two mucinous cystadenocarcinomas and a dermoid cyst with squamous cell carcinoma; all these tumors significantly demonstrated extensive necrotic changes at postoperative histopathologic examination.
Among the 64 ovarian tumors with an intratumoral blood flow, 44 were postoperatively diagnosed as benign and 20 were diagnosed as malignant based on histopathologic examinations.
The histopathologic types of these tumors and their numbers are shown in Table 1. Transvaginal color Doppler imaging of ovarian tumors arrowheads: the sampling vessels.
A A malignant tumor adenocarcinoma is shown to have a rich intratumoral blood flow while also displaying low resistance blood flow waveforms. B A benign ovarian tumor mature cystic teratoma is shown to have a poor intratumoral blood flow while also displaying high resistance blood flow waveforms. Malignant ovarian tumors significantly showed a low RI mean, 0. The sensitivity, specificity, and accuracy of the preoperative RI in detecting malignant ovarian tumors were In benign tumors, the mean RI value in corpus luteum cysts was 0.
Conversely, in malignant tumors, no statistical differences between the histopathologic types and the mean RI values were found Table 2.
The intensity of SMA expression in the tumor vessels in malignant ovarian tumors was significantly lower than that in benign tumors. Moreover, the tumor vessels in benign ovarian tumors displayed a constant high density of smooth muscle cells that was identified by the SMA immunostaining, whereas the tumor vessels in malignant ovarian tumors demonstrated an attenuated or discontinuous density of these cells Figs.
The average of the SMA expression index in malignant and benign ovarian tumors was 0. These findings suggest that malignant ovarian tumors showed either only a slight or lacking muscular coat within the tumor vessels in comparison with that of benign tumors.
Conversely, the intensity of CD34 expression in malignant ovarian tumors was significantly stronger than that in benign tumors Figs. The average CD34 labeling index in malignant ovarian tumors was significantly higher 0. These findings thus suggest that malignant ovarian tumors showed higher endothelial activity than benign tumors. Intensity of CD34 expression in the endothelial cells within the tumor vessels in malignant ovarian tumors B: mucinous cystadenocarcinoma was significantly stronger than that in benign tumors A: mucinous cystadenoma.
The arrows show the tumor vessels in the stroma of mucinous cystadenoma. Microvessel counts in both malignant and benign ovarian tumors varied from 8. The average count of 20 malignant and 44 benign tumors were Therefore, no significant difference was found in the MVD between the benign and malignant ovarian tumors with an intratumoral blood flow. Most of the recent studies using CDU have succeeded in detecting angiogenesis within the solid tumors.
Many authors also have suggested the clinical usefulness of this new sonographic approach for differentiating malignant from benign tumors, especially in ovarian tumors.
In this study, malignant ovarian tumors also showed a significantly low RI mean, 0.
Among the benign tumors, the mean RI in the corpus luteum cysts was significantly lower than that in other tumors mucinous cystadenomas, endometriomas, mature cystic teratomas, and follicular cysts , which suggests that the neovascularization in these cysts was similar to the physiologic angiogenesis in the corpus luteum. Moreover, several reports recently have shown significant overlapping in the Doppler values between benign and malignant ovarian tumors.
The low resistance to blood flow observed in malignant ovarian tumors may be explained by the histologic feature of the tumor vessels.
The tumor vessels in human carcinomas are primitive, lack a continuous smooth muscle layer, and often are comprised of an endothelial layer and a connective tissue alone. This study first showed that the density of smooth muscle cells, expressed by SMA within the tumor vessels of malignant ovarian tumors, was significantly poorly developed compared with that of benign tumors.
This finding may support the histopathologic study of Fleischer et al, 35 and thus suggests that a low resistance to blood flow in malignant ovarian tumors may be associated with the relative paucity of a muscular coat in the tumor vessels. Moreover, to the authors' knowledge, no reports have examined immunohistochemically the endothelial cells within the tumor vessels in any tumors that have been preoperatively analyzed by CDU.
This study first showed that intensity of CD34 expression in tumor vessels in malignant tumors was significantly stronger than that of benign tumors, thus suggesting that the endothelial cell activity might correlate with the histopathologic grades of ovarian tumors. Several studies regarding "endothelial cell proliferation" also have been investigated recently in carcinomas of the breast, colorectum, and ovary.
Recent studies have shown that measuring the MVD may be a manner of assessing tumor angiogenesis as an independent prognostic factor for predicting tumor growth and metastasis.
However, using such immunohistochemical techniques, there might be difficulty in distinguishing the newly formed vessels neovascularization from native ones, especially in some benign tumors. Therefore, in this study, large vessels with thick muscular walls and large vessels with wide lumina were excluded from the count, as discussed by Bosari et al.
Moreover, to the authors' knowledge, only two reports have investigated MVD in ovarian carcinomas. However, none of these studies examined MVD in benign tumors of the ovary. Moreover, no significant difference was found in mean MVD between malignant and benign ovarian tumors. These findings thus suggest that no correlation was found between the histopathologic benign or malignant features and MVD in ovarian tumors with an intratumoral blood flow.
Therefore, more careful evaluations will be necessary, regardless of whether MVD is a parameter predicting tumor behavior and survival in patients with malignant ovarian tumors. The authors thank Ms.
Ishiguro for technical assistance and Brian T. Quinn for critical comments on the article. Volume 80 , Issue 5. If you do not receive an email within 10 minutes, your email address may not be registered, and you may need to create a new Wiley Online Library account.
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If the address matches an existing account you will receive an email with instructions to retrieve your username. Original Article Free Access. Makoto Emoto M. Hiroshi Iwasaki M. Kumi Mimura M.