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T-cell recruitment to skin tissues is essential for inflammation in different cutaneous diseases; however, the mechanisms by which these T cells access the skin remain unclear. High endothelial venules expressing peripheral node address in (PNAd), an L-selectin ligand, are located in secondary lymphoid organs and are responsible for increasing T-cell influx into the lymphoid tissues. They are also found in non-lymphoid tissues during inflammation. However, their presence in different common inflammatory cutaneous diseases and their correlation with T-cell infiltration remain unclear. Herein, we explored the mechanisms underlying the access of T cells to the skin by investigating the presence of PNAd-expressing vessels in different cutaneous diseases, and its correlation with T cells' presence. Skin sections of 43 patients with different diseases were subjected to immunohistochemical and immunofluorescence staining to examine the presence of PNAd-expressing vessels in the dermis. The correlation of the percentage of these vessels in the dermis of these patients with the severity/grade of CD3+ T-cell infiltration was assessed. PNAd-expressing vessels were commonly found in the skin of patients with different inflammatory diseases. A high percentage of these vessels in the dermis was associated with increased severity of CD3+ T-cell infiltration (P < 0.05). Additionally, CD3+ T cells were found both around the PNAd-expressing vessels and within the vessel lumen. PNAd-expressing vessels in cutaneous inflammatory diseases, characterized by CD3+ T-cell infiltration, could be a crucial entry point for T cells into the skin. Thus, selective targeting of these vessels could be beneficial in cutaneous inflammatory disease treatment. In our study, we observed that PNAd-expressing vessels, identified as a crucial gateway for CD3+ T-cell entry into secondary lymph nodes, are a hallmark feature in the dermis across various CD3+ T-cell-mediated cutaneous diseases. This observation correlates with the extent of CD3+ T-cell infiltration within these conditions, suggesting that PNAd-expressing vessels may serve as a critical conduit for CD3+ T cells into the skin. Graphical Abstract [ABSTRACT FROM AUTHOR]

A number of social and cultural practices are prevalent in the Middle-East celebrating various occasions or to treat health conditions. These often result in dermatoses that are unfamiliar and confusing to dermatologists outside this region. This paper reviews skin manifestations emanating from traditional and ritual practices in Arab countries, particularly those from Saudi Arabia. [ABSTRACT FROM AUTHOR]