The Current Understanding on Langerhans' Cells and Its Role in Oral Lesions.

OBJECTIVE: Description of Langerhans' cells (LCs) as an important antigen-presenting cells responsible for detecting the antigens, recruiting T-cells, and thereby initiating the immune response. An adequate response of the mucosal immune system is essential to protect the mucosa against pathological conditions. Hence, a detailed review was planned about this unique antigen-presenting cell. METHODS: A literature search of the electronic databases included the MEDLINE, EBSCOHOST, PUBMED, and hand searches of references retrieved were undertaken using the following MeSH terms "Langerhans cells," "LCs in Oral Lichen Planus," "Langerhans cell histiocytosis," "LCs and HIV," "LCs in Periodontitis." RESULTS: LCs are present suprabasally in the epithelium of oral mucosa and in the epidermis of the skin. The role played by LCs though not fully elucidated, but several research studies indicate that these cells are involved in the pathogenesis of many oral diseases. In this article, the historical perspective, structure, function, origin, and phenotypic expressions of LCs are discussed in detail. The current understanding on the role of LCs in various oral lesions and its immunological characteristics are discussed. CONCLUSION: LCs act as immune mediator cells, tumor cells, vectors of infected cells, and phagocytic cells. Further studies could bolster the knowledge about the role of Langerhans cells in the immune response of various oral diseases and thereby provide diagnostic tools and help for prognostic evaluation. This review illuminates the pivotal role of Langerhans cells and its immune surveillance as a "Sentinels" of the oral mucosa.

Structure, function and role of CD44 in neoplasia.

CD44 is a group of protein molecules which perform a variety of functions. Their wide range of functions are mainly based on their multiple variations in their molecular structure. Furthermore, they are distributed in various tissues of the human body. They have a unique property of cell adhesion, which can lead to interaction between two different cells or a cell and its pericellular matrix. CD44 as a cell surface adhesive molecule helps in aggregation and migration of tumor cells. CD44 plays an important role in cancer of bladder, liver, lungs, pancreas, etc. Expression profile of CD44 has been seen in the epithelia of the lip, tongue, gingiva, hard palate, floor of the mouth, buccal mucosa and pharynx. The relationship between the expression of CD44 v6 and regional lymph node metastasis has been studied immunohistochemically. The expression of CD44 v6 was apparently downregulated in oral squamous cell carcinoma, but not in normal oral mucosa. Carcinomas expressing lower levels of CD44 v6 exhibited more frequent regional lymph node metastasis. No significant relation was found between the expression of CD44 v6 in primary and metastatic lesions. Still, the precise function of CD44 in the metastatic process and the degree of involvement in human malignancies is yet to be established.

A rare case report of craniofacial fibrous dysplasia.

Fibrous dysplasia (FD) is a fibro-osseous lesion of the osseous structures of the body. The exact cause is unknown; however, recently, the cause has been reported to be postzygomatic somatic mutation in guanine nucleotide-binding protein, alpha stimulating 1 gene located at chromosome 20q13.2. The three subtypes of FD are monostotic, polyostotic and craniofacial. The term craniofacial FD (CFD) is used to describe FD where the lesions are confined to contiguous bones of the craniofacial skeleton. This report describes the case of CFD of a 20-year-old male patient who had unusual presentation involving right maxilla and frontal bone of the left side of the face. The clinical features, radiological findings and treatment have been discussed.