الفهرس 
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Abstract
Oral squamous cell carcinoma accounts for more than 90% of all oral cancers. Less than 40% of the OSCC patients who present nodal involvement survive after five years, compared to a 90% survival rate for patients without metastasis.
An understanding of the molecular mechanisms involved in OSCC progression would be helpful to attain an early detection and develop more effective treatments with consequent longer survival.
Within the tumors, the development and metastasis require the induction of angiogenesis from a pre-existing vascular network, which guarantees the deliv¬ery of oxygen, nutrients and growth factors. For this reason, tumors with a higher vessel density seem to progress earlier than tumors with a poor vascular background.
Many studies have shown that the microvessel density (MVD) could represent a valid independent prognostic factor for the overall survival. Furthermore, a significant correlation between high micro-vascularization, the presence of metastasis and poor prognosis was detected.
Some authors also have suggested that lymphangiogenesis plays an active role in metastasis and that the intratu¬moral lymphatic density should be considered as a prognostic factor.
The anti-CD34 antibody is a monoclonal antibody that recognizes a cell-surface antigen that is expressed selectively in human hematopoietic progenitor cells and in the vascular endothelium.
The anti-D2-40 antibody is a selective marker for podo¬planin which is expressed specifically in lymphatic endothe¬lial cells but not in blood endothelial cells and has been used as a specific marker for the rec¬ognition of lymphatic vessels.
The presence and density of lymphatic and blood vessels in the intra and peritumoral tissues could play a key role in the progression, dis-semination and metastasis of carcinomas. However, for OSCC, the evidence is still insuffi¬cient.
The aim of the present study was to assess and correlate the MVD and LVD in the primary tumors of OSCC cases with the lymph node status.
In the present study, a total of twenty-two patients with OSCC were included. Eleven cases were proved histologically to be associated with positive lymph node, while the other eleven were associated with negative lymph node.
Their age ranged between 35 and 76 years. Twelve patients were males and ten patients were females.
The most common site of occurrence was the lateral side of the tongue (45.45%). The second common site of OSCC was the buccal mucosa (27.2%), followed by the alveolar mucosa (9%). Finally, the floor of the mouth, the ventral surface of the tongue, the tip of the tongue and the palate were the least occurring site (4.5%) for each site.
The biopsies were histologically evaluated using Haematoxylin and Eosin (H&E) staining. The microscopical examination revealed that 82% of the cases were moderatly differentiated OSCC.
Serial sections were immunohistochemically stained by monoclonal antibody to CD34 and D2-40 using LSAB complex method. The microvessel and lymph vessel densities were measured using the hot spot method and the results were correlated with the lymph node status.
All the cases showed immunoreactivity to both markers CD34 and D2-40. The antibody CD34 strongly stained the endothelial lining of the blood vessels whereas the lymph vessels showed no immunolabeling. On the other hand, The D2-40 antibody electively stained irregular vessels devoid of RBCs corresponding to lymph vessels while the blood vessels remained unstained.
It was found that the peri-tumoral lymph vessels are higher in density than the intratumoral vessels. In addition, apart from lymphatic vessels, D2-40 was also expressed by some tumor cells, which made counting of intratumoral lymphatic vessels relatively difficult.
The difference in both the mean MVD and the mean LVD between the lymph node positive and negative groups using (student t-test) was statistically significant (P< 0.001).
In addition, the difference between both the mean MVD and the mean LVD in each of the positive lymph nodes, negative lymph nodes, and the total OSCC cases was statistically significant (paired t-test).
On the other hand, the difference between both the mean MVD and the mean LVD in the well, moderately and poorly differentiated groups using f-test (ANOVA) was statistically insignificant (P>0.05).
Finally, the differences between both the mean MVD and the mean LVD concerning the age (r: Pearson coefficient), sex (student t-test), and site (ANOVA) were statistically insignificant.
from the current study, it could be concluded that CD34 and D2-40 can be detected immunohistochemically in human tissues of OSCC. MVD and LVD are significantly correlated with the lymph node status, while there is no significant correlation with either the histological grading, age, sex, or site. This would support the possibility of using MVD and LVD as indicators for lymph node metastasis.