Light and electron microscopic study of liquefaction degeneration in oral lichen planus

Cytological and cytochemical investigations on granular cells in oral lichen planus

Two biopsy specimens showed unusual histology characterized by features consistent with resolving oral lichen planus and voluminous, finely granular cells in the lamina propria, resembling the cells of granular cell tumour. Immunocytochemistry and lipid-pigment histochemistry indicated that the granular cells are macrophages of low proliferative activity laden with early ceroid. It is likely that damaged basal keratinocytes provide debris for the formation of the latter. "Oral ceroid granuloma' would be an appropriate term for collections of such reactive macrophages occurring in the oral tissues.

Cytological and cytochemical investigations on granular cells in oral lichen planus

Two biopsy specimens showed unusual histology characterized by features consistent with resolving oral lichen planus and voluminous, finely granular cells in the lamina propria, resembling the cells of granular cell tumour. Immunocytochemistry and lipid-pigment histochemistry indicated that the granular cells are macrophages of low proliferative activity laden with early ceroid. It is likely that damaged basal keratinocytes provide debris for the formation of the latter. 'Oral ceroid granuloma' would be an appropriate term for collections of such reactive macrophages occurring in the oral tissues.

Electron microscopic study on cell-to-cell interactions in oral lichen planus

Ultrastructural analysis of oral lichen planus was performed in 18 cases, focusing on cell-to-cell interactions. In the peripheral portion of the lesion, the most consistent findings were a widening of intercellular spaces, separation of the basement membrane (BM) from basal cells and scarce inflammatory cells. In the central portion of the lesions basal cells and BM showed severe damage and numerous inflammatory cells infiltrated into both the epithelium and subepithelial stroma. The infiltrates predominantly consisted of T-lymphocytes, a few Langerhans cells (LC) and macrophages. Most lymphocytes were large and positive for CD45RO. Dendritic LC and macrophages with cytoplasm containing abundant organelles were seen in the epithelium and subepithelial stroma, respectively. Close contacts of lymphocytes with LCs, macrophages and also with keratinocytes were sometimes observed in the central portion. In the subepithelial stroma, some lymphocytes contacted an HLA-DR+ dendritic cell, which was possibly a macrophage, forming a rosette-like arrangement. Conjugations between CD4 cells and dendritic cells (possibly LC) and also between CD8 cells and basal cells were observed in the epithelium. These T cells were large in size, and the CD8 cells which made contact with degenerated keratinocytes possessed cytoplasm containing numerous polarized organelles and a nucleus toward and contrary to the contact side, respectively. These lymphocytes expressed LFA-1 on the cell surface, and many basal cells exhibited ICAM-1. These findings indicate that T cells may receive information from LC and macrophages concerning degenerative keratinocytes, and that informed T cells attack perhaps the keratinocytes.

Human papillomavirus (HPV) infections and their associations with oral disease

More than 65 distinct types of human papillomavirus (HPV) have been identified to date. Several of the HPV types have been proposed as etiologic agents of squamous cell carcinoma. In the oral cavity, HPVs have been found associated with several benign squamous cell proliferations. Evidence from histology and DNA hybridization studies suggests that HPV is also involved in oral carcinogenesis. It is apparent, however, that substantial amount of confusion exists in the diagnosis of oral HPV infections. The keratotic, papillary lesions in the oral cavity are usually small and easily overlooked. The gross appearance of these viral lesions is not distinct enough to be readily diagnosed by the clinicians. Degenerative changes found on oral mucosa frequently simulate koilocytosis. Thus, caution should be exercised to avoid overdiagnosis of HPV infection in the oral cavity. The present review summarizes the current evidence available on HPV infections in general and on oral HPV infections in particular. The diagnostic techniques available as well as the problems encountered in the distinction of these lesions are also discussed in short.

Ultrastructure of oral leukoplakia and lichen planus. I. Basal region and inflammatory cells

Nine cases of homogenous leukoplakia and 21 cases of lichen planus (11 reticular and 10 erosive) were studied under the electron microscope. The changes found in leukoplakia were limited to occasional breaks in the basal lamina and modest changes in the cytoplasm of the basal cells. The basal lamina in lichen planus was found to exhibit 3 distinctly different pictures reflecting the clinical types of lichen planus. The structural abnormalities in the basal cells increased with increasing severity of the lesions. The inflammatory infiltrate in lichen planus was found to contain mainly small-to-medium-sized lymphocytes but plasma-cells with widely dilated rough endoplasmic reticulum containing a granular substance were frequently seen. Similar changes are seen in other disorders and, therefore, specific diagnostic criteria cannot be established on the basis of the present material.

Gingival basement membrane antigens in desquamative lesions of the gingiva

Desquamative gingival lesions are a clinical manifestation of several entities where histologic alterations in the gingival basement membrane are frequent. Normal and lesional gingival specimens from six patients with desquamative lesions of the gingiva associated with cicatricial pemphigoid or lichen planus and from one normal subject were examined by indirect immunofluorescence for immunologic alterations in basement membrane antigens. In four out of five desquamative gingival lesions from patients with lichen planus, type IV collagen and EBA basement membrane antigens were interrupted, thickened, or partially or completely absent as compared to normal gingiva. One specimen showed multiplication and duplication of the basement membrane. In the two desquamative gingival lesions from patients with cicatricial pemphigoid, type IV collagen was either partially absent or associated with the connective tissue side of the subepithelial bullae. These results suggest structural alterations in antigens within the basement membrane of patients with desquamative lesions of the gingiva.

Immunologic findings of oral lichen planus

Immunofluorescence (IFL) examination in lichen planus (LP) often reveals fibrin deposition in the basement membrane (BM) zone and colloid bodies (CB) giving a positive IgM fluorescence. Oral biopsies were taken from the involved buccal mucosa of 10 LP patients. IFL examination showed fibrin deposition in the BM area of all patients but in none of the seven controls. CB were found in the upper connective tissue of 5/10 oral and 3/3 skin specimens and they were always positive for fibrin, IgM and keratin. Positive staining with keratin antiserum suggests the epithelial origin of CB but the importance of fibrin and IgM staining remains unknown. Double IFL staining revealed that in areas of heavy fibrin deposition and CB formation the laminin and fibronectin staining was absent, suggesting a damage to BM. Moreover, IFL examinations with serum amyloid P (SAP) antiserum and basic fuchsin (BF) showed alterations indicating that upper connective tissue elastic fiber system is also involved in oral LP.

The role of dental restorative metals in the pathogenesis of oral lichen planus

Twenty-four subjects with oral lichen planus and twelve control subjects without oral mucosal disease were patch tested with dental restorative metals and selected metallic salts. Twenty-one percent of the lichen planus population exhibited a positive skin response to one or more challenge materials, as compared to 8% of the control population. It is concluded that oral lichen planus subjects show a higher correlation with delayed hypersensitivity to dental metals than a control population; however, a cause-and-effect relationship cannot be substantiated.

Verrucous lupus erythematosus: ultrastructural studies on a distinct variant of chronic discoid lupus erythematosus

Ten patients with classic discoid lupus erythematosus of the face associated with verrucous, papulonodular lesions on the arms and hands were studied by electron microscopy. The ultrastructural findings on the verrucous lesions included apoptotic keratinocytes, intraepidermal lymphocytes, and gapping, detachment, and reduplication of the basal lamina. Also, tubuloreticular inclusion bodies were present in the endothelial cells. These observations, together with the clinical, histopathologic, and immunofluorescence findings, suggest that the verrucous lesions represent a rare, but distinct, variant of chronic discoid lupus erythematosus.

A quantitative study of lamina densa alterations in hamster cheek pouch carcinogenesis

Lesions produced by topical application of 0.5 per cent. DMBA to the hamster cheek pouch epithelium were classified as hyperplasia, dysplasia and carcinoma groups using strict histological criteria. Untreated epithelium served as a control. Tissue samples from five animals in each group were processed for electron microscopy and electron micrographs from the epithelial-connective tissue junction were obtained from 5 blocks per animal. The micrographs were subjected to stereological intersection counting to determine the relative surface (SSLD, BM) of lamina densa which was in normal relationship to the basal cell plasma membranes. Quantitative results indicated a progressive loss of lamina densa during carcinogenesis and this was accompanied by the extrusion of pseudopodia from the basal cells through the gaps. The pseudopodia were frequently related to peripheral cytoplasmic microfilaments. Quantitative data confirmed the progressive nature of this loss, with values for SSLD,BM being of the order of 98 per cent., 88 per cent., 76 per cent, and 42 per cent. for normal epithelium and for the hyperplastic, dysplastic and carcinomatous lesions respectively. The loss of lamina densa is discussed in relation to the specificity of the response and to the development of features indicative of motility in transforming cells.

Ultrastructural study of lichen planus: an evaluation of the colloid bodies

Colloid bodies, which are eosinophilic, dyskeratotic, damaged epidermal cells that show signs of fibrinoid necrosis and premature keratinization, may play a role in the pathogenesis of lichen planus. An ultrastructural study of two patients with lichen planus focusing on the colloid bodies suggests the possibility of these bodies initiating the lichenoid dermal reaction.

Lichen planus: immunologic and morphologic identification of the submucosal infiltrate

The purpose of this investigation was to specifically identify T cells, B cells, and histiocytes in the infiltrate typically seen in lichen planus. In frozen tissue sections, AET-treated sheep erythrocytes formed immunologic rosettes with the lymphocytes in the infiltrate, designating them as T cells. Rosette assays with reagent erythrocytes, IgGEA, IgMEA, IgMEAC, and E resulted in nonadherence, indicating a lack of B cells and macrophages, and indirectly implicating them as T cells. Scanning electron microscopy of the cellular infiltrate, in situ, showed that the cells had smooth, nonvillous surfaces. These observations were consistent with a T cell origin and were considered supportive of the immunologic data. The results of this investigation support the hypothesis that lichen planus is a disease mediated by thymus-dependent lymphocytes.