Immunohistochemical and ultrastructural demonstration of keratin in epi-myoepithelial islands of autoimmune sialadenitis in man

Lymphoma in Sjögren's syndrome. From histopathology to molecular pathology

A number of autoimmune diseases predispose to the development of neoplasia. A particularly well-recognized association is the development of lymphoma in Sjögren's syndrome. Although this risk has been estimated to be 44 times that of the general population, few reliable prognostic indexes exist for individual patients. Recent advances in molecular biology have improved our understanding of Sjögren's syndrome and permitted better characterization of the generalized lymphoproliferation associated with the condition. This article reviews the histopathology of the major and minor salivary gland lesions of Sjögren's syndrome and discusses advances in molecular biology that have permitted more accurate prediction of lymphoma development in this group of patients.

Ultrastructure and three-dimensional imaging of epimyoepithelial islands in benign lymphoepithelial lesions

Benign lymphoepithelial lesions of the salivary glands associated with Sjögren's syndrome are characterized by extensive infiltration of lymphoid cells, atrophy of acini and the presence of so-called epimyoepithelial islands. This report describes ultrastructural and three-dimensional reconstructive studies of epimyoepithelial islands performed at Tokyo Women's Medical College. Ultrastructural examination showed that these islands are composed mainly of epithelial cells containing intermediate filaments and/or tonofilament bundles, scattered lymphocytes and plasma cells. Myoepithelium-like cells containing myofilaments were sometimes found in the peripheral portion of the myoepithelial islands. Also, mitotic figures were rarely found in these islands. Three-dimensional reconstructive study revealed that the epimyoepithelial islands are not isolated cell clusters but are continuous hypertrophic duct-like structures. These results suggest that the epimyoepithelial islands are derived from proliferating duct epithelial cells, especially those of large peripheral ducts.

Immunohistochemical demonstration of enamel proteins in odontogenic tumors

Immunohistochemical localization of two enamel proteins, amelogenin and enamelin, in comparison with that of keratin, was determined in odontogenic tumors and the allied lesions in order to verify functional differentiation of the tumor cells as ameloblasts. Amelogenin and enamelin were demonstrated in small mineralized foci and in the tumor cells surrounding them in adenomatoid odontogenic tumor (AOT), calcifying epithelial odontogenic tumor (CEOT), and calcifying odontogenic cyst (COC). Hyaline droplets in AOT showed positive staining for both enamel proteins. These mineralized and hyaline materials were not positive for keratin, although tumor cells were positive. On the other hand, no immunoreaction for enamel proteins was obtained in ameloblastoima and odontogenic epithelial cell nests within myxoma and epulis. The results suggest that tumor cells of AOT and CEOT and lining epithelial cells of COC show ameloblastic differentiation in part, but that ameloblastoma cells do not attain functional matauration as secretory phase ameloblasts.

Autoantibodies to keratin in Sjögren's syndrome

In order to determine which components of the salivary duct cells are recognized by the antisalivary duct antibodies, sera of patients with Sjögren's syndrome were screened for immunoreactivity to keratin by using an ELISA test and a Western blot analysis. The autoantibodies which reacted with keratin were demonstrated in 8 of 9 definite cases of Sjögren's syndrome and in 3 of 6 probable cases, and they reacted with different keratin peptides in each case. The results suggest that the antisalivary duct antibodies include antibodies against keratin, which exists ubiquitously as a cytoskeleton in the salivary gland epithelial cells. Detection of antikeratin antibody might be a useful aid for diagnosis of Sjögren's syndrome.

Immunohistochemical characterization of epithelial cells in human lacrimal glands. II. Inflammatory and neoplastic lesions of lacrimal glands

The distribution of cytokeratins (CK), actin, lactoferrin (Lf), lysozyme (Ly), vimentin and S-100 protein was immunohistochemically investigated in paraffin-embedded specimens of five inflammatory and five neoplastic lesions of lacrimal glands (LGs). Atrophic acini in dacryoadenitis reacted with antibodies (ABs) KL1 and Pkk1 (CK 7, 8, 17, 18) in a manner similar to ducts. Apart from myoepithelial cells and some luminal-duct cells, the remaining epithelia in dacryoadenitis were negative with AB 34 beta E12 (CK 5). The number of AB HHF35 (actin)-positive myoepithelial cells was not altered in dacryoadenitis. Epithelia in dacryoadenitis reacted weakly but consistently with Lf while revealing weak and inconsistent staining for Ly. Vimentin was negative in epithelial cells in dacryoadenitis except in one case. S-100 protein was detected only in epithelia of inflammatory major LGs. Epimyoepithelial islands in lymphoepithelial proliferation reacted variably for CKs, Lf, Ly and vimentin and remained negative for actin and S-100. In pleomorphic adenomas, neoplastic cells showing duct-like differentiation (luminal) reacted consistently with CK 7, 8, 17, 18 and S-100 protein and inconsistently with CK 5, Lf and Ly but remained negative for actin and vimentin. Other neoplastic cells (ovoid/peripheral cells) stained consistently for CK 5, vimentin and S-100 protein and focally for CK 7, 8, 17, 18, actin, Lf and Ly. Spindle-form neoplastic cells found in the stroma exhibited vimentin and S-100 protein and, less frequently, actin. Determination of these antigens in pleomorphic LG adenomas may help to evaluate their prognosis.

Immunohistochemical analyses of autoimmune sialadenitis in man

The immunoreactivity pattern for different monoclonal antibodies to cytokeratins and to vimentin in epimyoepithelial islands typical for glands of patients with Sjögren's syndrome has been compared with that of normal parotid gland tissue. Two types of epithelial island cells were observed: one had an intermediate filament protein pattern similar to that of ordinary duct epithelial cells of normal parotid gland. The other had an intermediate filament protein pattern typical of myoepithelial and/or basal duct cells in normal glands. Thus, we conclude that the islands are composed of a mixed population of gland cells on the basis of their content of cytokeratins or of cytokeratins and vimentin. These cells might originate from pluripotential reserve cells or from ordinary duct, myoepithelial and/or basal duct cells which may have undergone metaplasia.

Characterization of epimyoepithelial islands in benign lymphoepithelial lesions of major salivary gland: an immunohistochemical and ultrastructural study

Knowledge of the processes leading to the development of epimyoepithelial islands bears on histogenetic and morphogentic processes in salivary gland tumors. Immunohistochemical and ultrastructural investigations of the cellular composition of epimyoepithelial islands were carried out on three examples of benign lymphoepithelial lesions with varying histologic features. The monoclonal anti-keratin antibody 312C8-1, which specifically decorates myoepithelial cells of the normal salivary gland, also stains the myoepithelial cells surrounding residual acini and intercalated ducts in benign lymphoepithelial lesions and the cell population of epimyoepithelial islands, with the exception of persisting luminal epithelial cells. Ultrastructurally, the myoepithelial cells of involuting acini and ducts and the modified myoepithelial cells of epimyoepithelial islands, identified in both locations by the monoclonal antibody 312C8-1, show an increasing complement of tonofilament bundles. In addition, persisting lumens (often distended with lymphocytes) and definite luminal epithelial cells can be seen in electron micrographs of some epimyoepithelial islands. The designation for this characteristic epithelial feature of benign lymphoepithelial lesions is therefore appropriate.

Chronic sialadenitis. An immunocytochemical study in humans

The cellular changes in salivary gland parenchyma with chronic inflammation were studied immunocytochemically with a panel of antibodies. Myoepithelial cells were labelled with antimyosin, duct cells with a polyclonal anti-callus prekeratin, a monoclonal anti-keratin CAM 5.2 and a monoclonal anti-keratin 7 (RPN 1162), and a subpopulation of basal duct cells with a monoclonal anti-keratin 16a. The wide range of changes observed were similar to those described following experimental duct ligation. One of the most striking features was the survival of myoepithelial cells surrounding persisting acini and ductal structures. Most of these ductal structures appeared to be either surviving intercalated ducts or were altered acinar cells. There was no evidence of myoepithelial or ductal hyperplasia. The 16a positive basally located duct cells which are conspicuous in normal glands, pleomorphic adenomas and in the epithelial islands in lymphoepithelial lesions (Palmer et al. 1985; 1986) were virtually absent, except in one specimen with mild inflammatory changes. If this cell type represents a reserve cell, then loss of it may preclude recovery of the remaining parenchyma following resolution of inflammation.

Epimyoepithelial' islands in lymphoepithelial lesions. An immunocytochemical study

A panel of antibodies has been used in an immunoenzyme study in an attempt to characterize the cell types found in the 'epimyoepithelial' islands of lymphoepithelial lesions. Myoepithelial cells, which can be specifically stained with an anti-smooth muscle antibody were not found. The majority of cells stained with anti-prekeratin, suggesting a duct cell differentiation. A subpopulation of duct cells stainable with a monoclonal antikeratin (16a), previously described as occupying a basal location in normal salivary gland ducts, was clearly demonstrated. It is suggested that these cells may be important in the epithelial proliferation in these islands. The hyaline material within and surrounding the epithelial islands was positive for type IV collagen and therefore consists of basement membrane material.

The localization of cytoskeletal proteins and thyroglobulin in thyroid microcarcinoma in comparison with clinically manifested thyroid carcinoma

A comparative study was performed by the use of immunoperoxidase staining of 11 cases of thyroid microcarcinoma and 7 cases of clinically manifested thyroid carcinoma. Antibodies against four kinds of cytoskeletal proteins and thyroglobulin were used. In both the microcarcinoma and manifested carcinoma groups, actin and myosin were found in almost all neoplastic cells of all patients, and keratin and vimentin were present in the tumor cells of several patients. Keratin was found only in papillary carcinoma cells. Thyroglobulin was present in the neoplastic cells of several patients from each group; follicular carcinoma cells and keratin-negative cells reacted more strongly with thyroglobulin than did papillary carcinoma cells or keratin-positive cells. There was no special difference between microcarcinoma and clinically manifested carcinoma in the location of cytoskeletal proteins and thyroglobulin.

Glomus tumor of the cheek: an immunohistochemical demonstration of actin and myosin

A rare case of a buccal glomus tumor was examined by light and electron microscopy. Histologically, the tumor consisted of various vascular spaces surrounded by masses of epithelioid glomus cells, coexisting with a hemangiomatous proliferation of the vessels. Immunohistochemical stainings revealed that the tumor cells were positive for smooth-muscle actin and myosin, with various intensities of the stainings. The electron microscope invariably showed microfilaments in the tumor cells. The results suggest that the glomus tumor cells have characteristics of the smooth-muscle cell and the tumor has a hamartomatous nature.