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Wang XQ, Zhong NN, Man QW, Xu GC, Yan SC, Peng LW, Wang YG, Liu B, Bu LL, Li L. Single-cell RNA sequencing reveals tumor heterogeneity within salivary gland pleomorphic adenoma: A preliminary study. J Oral Pathol Med 2023; 52:766-776. [PMID: 37549038 DOI: 10.1111/jop.13465] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2023] [Revised: 06/23/2023] [Accepted: 07/06/2023] [Indexed: 08/09/2023]
Abstract
BACKGROUND Salivary gland pleomorphic adenoma (SPA) is a common neoplasm of salivary glands that displays remarkable histological diversity. Previous studies have demonstrated the involvement of gene rearrangements and cytoskeleton-remodeling-related myoepithelial cells in SPA tumorigenesis. Cytoskeleton remodeling is necessary for epithelial-mesenchymal transition (EMT), a key process in tumor progression. However, the heterogeneity of tumor cells and cytoskeleton remodeling in SPA has not been extensively investigated. METHODS An analysis of single-cell RNA sequencing (scRNA-seq) was performed on 27 810 cells from two donors with SPA. Bioinformatic tools were used to assess differentially expressed genes, cell trajectories, and intercellular communications. Immunohistochemistry and double immunofluorescence staining were used to demonstrate FOXC1 and MYLK expression in SPA tissues. RESULTS Our analysis revealed five distinct cell subtypes within the tumor cells of SPA, indicating a high level of intra-lesional heterogeneity. Cytoskeleton-remodeling-related genes were highly enriched in subtype 3 of the tumor cells, which showed a close interaction with mesenchymal cells. We found that tumoral FOXC1 expression was closely related to MYLK expression in the tumor cells of SPA. CONCLUSION Tumor cells enriched with cytoskeleton-remodeling-related genes play a crucial role in SPA development, and FOXC1 may partially regulate this process.
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Affiliation(s)
- Xi-Qian Wang
- Department of Oral and Maxillofacial Head Neck Surgery, Henan Provincial People's Hospital, Zhengzhou University People's Hospital, Henan University People's Hospital, Zhengzhou, Henan, China
- State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, Key Laboratory of Oral Biomedicine Ministry of Education, Hubei Key Laboratory of Stomatology, School & Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Nian-Nian Zhong
- State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, Key Laboratory of Oral Biomedicine Ministry of Education, Hubei Key Laboratory of Stomatology, School & Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Qi-Wen Man
- State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, Key Laboratory of Oral Biomedicine Ministry of Education, Hubei Key Laboratory of Stomatology, School & Hospital of Stomatology, Wuhan University, Wuhan, China
- Department of Oral and Maxillofacial - Head Neck Oncology, School & Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Guang-Cai Xu
- Department of Oral and Maxillofacial Head Neck Surgery, Henan Provincial People's Hospital, Zhengzhou University People's Hospital, Henan University People's Hospital, Zhengzhou, Henan, China
| | - Si-Chen Yan
- Department of Oral and Maxillofacial Head Neck Surgery, Henan Provincial People's Hospital, Zhengzhou University People's Hospital, Henan University People's Hospital, Zhengzhou, Henan, China
| | - Li-Wei Peng
- Department of Oral and Maxillofacial Head Neck Surgery, Henan Provincial People's Hospital, Zhengzhou University People's Hospital, Henan University People's Hospital, Zhengzhou, Henan, China
| | - Yong-Gong Wang
- Department of Oral and Maxillofacial Head Neck Surgery, Henan Provincial People's Hospital, Zhengzhou University People's Hospital, Henan University People's Hospital, Zhengzhou, Henan, China
| | - Bing Liu
- State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, Key Laboratory of Oral Biomedicine Ministry of Education, Hubei Key Laboratory of Stomatology, School & Hospital of Stomatology, Wuhan University, Wuhan, China
- Department of Oral and Maxillofacial - Head Neck Oncology, School & Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Lin-Lin Bu
- State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, Key Laboratory of Oral Biomedicine Ministry of Education, Hubei Key Laboratory of Stomatology, School & Hospital of Stomatology, Wuhan University, Wuhan, China
- Department of Oral and Maxillofacial - Head Neck Oncology, School & Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Li Li
- Department of Clinical Single-Cell Biomedicine Center, Henan Provincial People's Hospital, Zhengzhou University People's Hospital, Henan University People's Hospital, Zhengzhou, Henan, China
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Triantafyllou A, Ruggles N. Lysosomal and cytoskeletal events in epithelial salivary tumours as assessed by imunohistochemistry for CD63 and HSP27. Pathol Res Pract 2022; 229:153691. [DOI: 10.1016/j.prp.2021.153691] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 11/11/2021] [Accepted: 11/15/2021] [Indexed: 10/19/2022]
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Triantafyllou A, Thompson LDR, Devaney KO, Bell D, Hunt JL, Rinaldo A, Vander Poorten V, Ferlito A. Functional Histology of Salivary Gland Pleomorphic Adenoma: An Appraisal. Head Neck Pathol 2015; 9:387-404. [PMID: 25380577 PMCID: PMC4542802 DOI: 10.1007/s12105-014-0581-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Accepted: 10/29/2014] [Indexed: 11/29/2022]
Abstract
The complex microstructure of salivary gland pleomorphic adenoma is examined in relation to function. Events related to secretion of macromolecules and absorption, responses to the altered microenvironment and controversies concerning epithelial-mesenchymal transition versus modified myoepithelial differentiation are explored. Their effects on tumor cell phenotypes and arrangements are emphasized. Heterotopic differentiation and attempts at organogenesis are also considered. The approach allows interpreting microstructure independently of histogenetic perceptions, envisaging the tumor cells as a continuum, endorsing luminal structures as the principal components, and defining pleomorphic adenoma as a benign epithelial tumour characterized by variable epithelial-mesenchymal transition, secretion/differentiation and metaplasia.
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Affiliation(s)
- Asterios Triantafyllou
- />Oral and Maxillofacial Pathology, School of Dentistry, University of Liverpool, Liverpool, UK
- />Cellular Pathology, University Hospital Aintree, Liverpool, UK
| | | | | | - Diana Bell
- />Department of Pathology, MD Anderson Cancer Center, Houston, TX USA
| | - Jennifer L. Hunt
- />Department of Pathology and Laboratory Medicine, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR USA
| | | | - Vincent Vander Poorten
- />Otorhinolaryngology-Head and Neck Surgery, Department of Oncology, University Hospitals KU Leuven and Leuven Cancer Institute, Leuven, Belgium
- />European Salivary Gland Society, Geneva, Switzerland
| | - Alfio Ferlito
- />University of Udine School of Medicine, Udine, Italy
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Ihrler S, Weiler C, Hirschmann A, Sendelhofert A, Lang S, Guntinas-Lichius O, Arnold G, Zietz C, Harrison JD. Intraductal carcinoma is the precursor of carcinoma ex pleomorphic adenoma and is often associated with dysfunctional p53. Histopathology 2007; 51:362-71. [PMID: 17593217 DOI: 10.1111/j.1365-2559.2007.02736.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
AIMS Although intraductal carcinoma has been demonstrated in intracapsular carcinoma ex pleomorphic adenoma (CEPA), the morphological and genetic stages of transformation of pleomorphic adenoma (PA) to CEPA are not fully understood. The aim of this study was to investigate the morphology of intracapsular CEPA. METHODS AND RESULTS The largest series of intracapsular CEPA studied was subject to immunohistochemical double-staining to detect p53 protein and cellular proliferation in different types of cell combined with mutational analysis of the p53 gene in laser-microdissected material. Intraductal carcinoma with high-grade cellular atypia and frequent accumulation of p53 protein was found in 15/19 cases. Purely intraductal carcinoma was found in eight cases. Mutation of p53 was found in 7/19 cases, of which it was found in intraductal carcinoma in 5/15 cases. CONCLUSIONS The frequent demonstration of intraductal carcinoma indicates that this preinvasive lesion is likely to be a constant feature in the malignant transformation of PA to CEPA. It appears to be a feature of CEPA developing from both primary and recurrent PA. The combined immunohistochemical and genetic data show that 14/19 cases of CEPA and 11/15 cases with intraductal carcinoma showed genetic or morphological evidence of dysfunctional p53, indicating that this is an early event in malignant transformation.
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MESH Headings
- Adenoma, Pleomorphic/genetics
- Adenoma, Pleomorphic/metabolism
- Adenoma, Pleomorphic/pathology
- Adult
- Aged
- Aged, 80 and over
- Carcinoma, Intraductal, Noninfiltrating/genetics
- Carcinoma, Intraductal, Noninfiltrating/metabolism
- Carcinoma, Intraductal, Noninfiltrating/pathology
- DNA Mutational Analysis
- Disease Progression
- Female
- Humans
- Immunohistochemistry
- Keratin-14/analysis
- Keratin-7/analysis
- Ki-67 Antigen/analysis
- Male
- Middle Aged
- Models, Biological
- Mutation
- Salivary Gland Neoplasms/genetics
- Salivary Gland Neoplasms/metabolism
- Salivary Gland Neoplasms/pathology
- Salivary Glands, Minor/chemistry
- Salivary Glands, Minor/metabolism
- Salivary Glands, Minor/pathology
- Tumor Suppressor Protein p53/analysis
- Tumor Suppressor Protein p53/genetics
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Affiliation(s)
- S Ihrler
- Institute of Pathology, Ludwig Maximilian University, Munich, Germany.
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Harrison JD, Triantafyllou A, Baldwin D, Schäfer H. Histochemical and biochemical determination of calcium in pleomorphic adenoma. VIRCHOWS ARCHIV. B, CELL PATHOLOGY INCLUDING MOLECULAR PATHOLOGY 1993; 64:123-5. [PMID: 8220820 DOI: 10.1007/bf02915104] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Although calcification seldom occurs in pleomorphic adenoma, it often occurs in salivary glands, and so we decided to investigate the possible role of calcium in this difference. A histochemical method using glyoxal bis(2-hydroxyanil) demonstrated a small amount of calcium outlining lumina and separated cells of epithelial structures and associated with cells of myxoid and chondroid regions in pleomorphic adenoma, and a conspicuous amount in the acini of the associated salivary glands. A biochemical method using dry ashing demonstrated a significantly higher level of calcium in the glands than in pleomorphic adenoma. The results indicate that the calcium is mainly associated with secretory granules, which are scarce in pleomorphic adenoma, and with proteoglycan present intercellularly and in stromal regions of pleomorphic adenoma. The calcium in secretory granules is of possible importance in calcification in lumina and epithelium, and that bound to proteoglycan is possibly released following necrosis to be of importance in stromal calcification. However, the overall low level of calcium in pleomorphic adenoma is the likely explanation for the usual lack of calcification.
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Affiliation(s)
- J D Harrison
- Department of Oral Pathology, King's College School of Medicine and Dentistry, London, England
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Harrison JD, Auger DW. Mucosubstance histochemistry of pleomorphic adenoma of parotid and submandibular salivary glands of man: light and electron microscopy. THE HISTOCHEMICAL JOURNAL 1991; 23:293-302. [PMID: 1723726 DOI: 10.1007/bf01044960] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Lumina and adluminal cells in human salivary gland pleomorphic adenomas were found to contain neutral, carboxylated, and occasionally sulphated glycoproteins. A variable component of luminal contents and secretory granules did not appear to contain glycoprotein and possibly consisted of protein. Glycosaminoglycans, which appeared to be hyaluronic acid and chondroitin sulphate, were demonstrated rarely in lumina, often between epithelial cells, and forming the matrix of myxoid tissue and, together with collagen, chondroid tissue. No differences were seen between tumours from parotid glands and those from submandibular glands. Glycoproteins demonstrated in the epithelium are similar to those of intercalary ducts of parotid and submandibular glands, and may represent a primitive form of salivary secretion. Glycosaminoglycans secreted intercellularly by epithelial cells cause their increasing separation to form myxoid or chondroid tissue. This stromalization extends to lumina to produce a loss of epithelium. Pleomorphic adenoma appears to be a manifest example of variable derepression of the genotype.
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Affiliation(s)
- J D Harrison
- Department of Oral Pathology, The Rayne Institute, King's College School of Medicine and Dentistry, London, UK
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Harrison JD. Ultrastructural observation of calcification in a pleomorphic adenoma of the parotid gland. Ultrastruct Pathol 1991; 15:185-8. [PMID: 2038778 DOI: 10.3109/01913129109016237] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
A pleomorphic adenoma was examined by electron microscopy. Calcification was found in a lumen and in epithelial cells and consisted of needle-shaped crystals that contained calcium and phosphorus and were probably apatite. Small collections of crystals in the lumen, which were often associated with membranous cellular debris, appeared to form larger calcified masses by fusion. Collections of crystals were seen in vacuoles in adluminal cells. The calcification in the lumen may have started on membranous cellular debris, and that in the adluminal cells may have arisen either by endocytosis of luminal material or by autophagocytosis. The calcification appears to relate to the old age of the tumor.
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Affiliation(s)
- J D Harrison
- Department of Oral Pathology, Rayne Institute, King's College School of Medicine and Dentistry, London, England
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Harrison JD, Auger DW. Ultrastructural morphology of secretory granules in pleomorphic adenoma of human parotid and submandibular salivary glands. Arch Oral Biol 1989; 34:759-61. [PMID: 2560368 DOI: 10.1016/0003-9969(89)90083-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Secretory granules were found in some of the cells lining the lumina of typical epithelial structures in pleomorphic adenomas. They were small, of varied electron density, and were mostly unipartite, sometimes bipartite and occasionally tripartite. They most closely resembled secretory granules of intercalary ductal cells of normal salivary glands.
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Affiliation(s)
- J D Harrison
- Department of Oral Pathology, Rayne Institute, King's College School of Medicine and Dentistry, London, England
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Harrison JD, Auger DW. Ultrastructural observations on luminal structures of pleomorphic adenoma of parotid and submandibular salivary glands of man. VIRCHOWS ARCHIV. A, PATHOLOGICAL ANATOMY AND HISTOPATHOLOGY 1989; 415:559-63. [PMID: 2552653 DOI: 10.1007/bf00718650] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Luminal structures found in salivary pleomorphic adenomas consisted of lumina surrounded by epithelial cells that varied from being packed together to being widely separated except at the luminal margin. Communication between lumina and the surrounding stroma was occasionally seen. Secretory material and cellular debris were seen in lumina, invaginations of the luminal surfaces of periluminal cells, associated vesicles, and vacuoles. Secretory granules, lysosomes and lipofuscin were seen in periluminal cells. Secretory material and debris from necrotic periluminal cells appear to accumulate in lumina, and to be endocytosed and degraded lysosomally by periluminal cells. The finding of communications between lumina and the surrounding stroma suggests that the stromalization of the epithelium includes the luminal structures. The present investigation supports the hypothesis that many of the cellular features of the pleomorphic adenoma relate to the microenvironment.
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Affiliation(s)
- J D Harrison
- Department of Oral Pathology, Rayne Institute, King's College School of Medicine and Dentistry, London, United Kingdom
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Harrison JD, Auger DW, Paterson KL, Rowley PS. Mucin histochemistry of submandibular and parotid salivary glands of man: light and electron microscopy. THE HISTOCHEMICAL JOURNAL 1987; 19:555-64. [PMID: 3440756 DOI: 10.1007/bf01687363] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Light-microscopy showed parotid serous acinar cells to contain neutral mucin, serous and mucous acinar cells of submandibular gland and intercalary ductal cells of both glands to contain acid and neutral mucins, and cells of striated ducts and excretory ducts to contain neutral mucin. Mucins were demonstrated ultrastructurally in a portion of the components of secretory granules of acinar cells and intercalary ductal cells, and in secretory granules of striated and excretory ductal cells. The mucins were all stained by techniques that reveal 1,2-glycols. Secretory granules of submandibular mucous and serous acinar cells and intercalary ductal cells were stained variably by the low iron-diamine technique for acid mucin, and those of mucous acinar cells by the high iron-diamine technique for sulphomucins mucin and possibly consisted of protein. The results suggest that one type of cell may be able to produce a range of secretory products and to package them variously into secretory granules.
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Affiliation(s)
- J D Harrison
- Department of Oral Pathology, Rayne Institute, King's College School of Medicine and Dentistry, London, UK
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Harrison JD, Auger DW, Badir MS, Paterson KL. Ultrastructural morphology of secretory granules of submandibular and parotid salivary glands of man. Arch Oral Biol 1987; 32:229-34. [PMID: 3478025 DOI: 10.1016/0003-9969(87)90015-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Morphological variation among secretory granules of the same type of cell was found in the acini, intercalary and striated ducts, and collecting-ducts, and was greatest in serous and intercalary-duct cells. Secretory granules of monopartite and bipartite structure were seen in all these cell types; tripartite forms were seen in serous and intercalary-duct cells. A possible explanation for the variation is that one type of cell may be able to produce a range of secretory products and package them variously into secretory granules, thus creating different appearances.
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Affiliation(s)
- J D Harrison
- Department of Oral Pathology, Rayne Institute, King's College School of Medicine and Dentistry, London, England, U.K
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Palmer RM. The identification of myoepithelial cells in human salivary glands. A review and comparison of light microscopical methods. JOURNAL OF ORAL PATHOLOGY 1986; 15:221-9. [PMID: 2425066 DOI: 10.1111/j.1600-0714.1986.tb00612.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Myoepithelial cells have frequently been implicated in salivary gland tumour histogenesis. A major problem has been the reliable identification of these cells at the light microscopical level, both in tumours and in normal salivary glands. Many methods have been advocated, often with comparatively little evaluation in normal human tissue and with limited comparison between techniques. This paper reviews the application of histological staining techniques, enzyme histochemistry and immunocytochemistry with antibodies to actin, myosin and keratins. The only reliable method was immunocytochemistry with an antibody to smooth muscle myosin, with immunofluorescence on frozen tissue and immunoenzyme labelling on methacarn-fixed/paraffin-processed material. Formalin fixation did not permit successful staining. Monoclonal antibodies to specific keratin polypeptides may prove to be a useful label of myoepithelial cells but at the present time the available cytokeratin antibodies preferentially stain duct cell populations.
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Palmer RM, Lucas RB, Langdon JD. Ultrastructural analysis of salivary gland pleomorphic adenoma, with particular reference to myoepithelial cells. Histopathology 1985; 9:1061-76. [PMID: 3002941 DOI: 10.1111/j.1365-2559.1985.tb02785.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Previous ultrastructural studies of pleomorphic adenoma have presented conflicting results with regard to the role of myoepithelial cells in the histogenesis of this tumour. In the present study specimens of ten major salivary gland pleomorphic adenomas were examined ultrastructurally and a number of cell types identified. The material was subjected to quantification using the stereological method of point counting. The results showed a wide spectrum of differentiation within these tumours in which typical myoepithelial cells were rarely encountered even in situations where they are reported to occur in routine histological preparations. Cells with some myoepithelial features were more numerous but duct cells accounted for the majority of tumour cells. The ultrastructural findings correlated well with previously reported immunocytochemical data and further support certain ideas about salivary gland tumour histogenesis.
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The pleomorphic adenoma of salivary glands transplanted on athmymic mice. A lightmicroscopical and immunohistochemical investigation. VIRCHOWS ARCHIV. A, PATHOLOGICAL ANATOMY AND HISTOPATHOLOGY 1985; 408:191-209. [PMID: 2417405 DOI: 10.1007/bf00707982] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
10 pleomorphic adenomas of the human parotid gland were transplanted on several groups of nude mice. For comparative reasons, 10 other pleomorphic adenomas, a neurinoma and a chordoma and transplants of squamous cell carcinomas and of normal salivary gland tissue were also analysed. In the primary tumours and in the transplants, the presence of keratin, carcinoembryonic antigen, tissue polypeptide antigen, lactoferrin, lysozyme, immunoglobulins, secretory component, amylase, fibronectin and of several lectin-receptors (PNA, WGA, HPA, Ulex europaeus) was sought. The immunohistological observations show that many of the features of a pleomorphic adenoma are constant under the conditions of transplantation. In the transplanted tumour, the same heterogeneity as in the primary tumours can be observed. Autoradiographic studies show little labelling with 3-H thymidine, which is in good accordance with the biological behaviour of the tumour. The distribution of fibronectin shows an interesting association with myoepithelial-like cells. Our results support the hypothesis that the histogenetic origin of the pleomorphic adenoma is a cell pool of the terminal ductal segment. A differentiation towards ductal cells (with production of secretory substances) and towards myoepithelial cells (associated with large amounts of basal membrane like substances) is observed.
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Abstract
Two meningiomas were investigated that consisted largely of myxoid tissue. Staining with Alcian blue and incubation with staphylococcal, Streptomyces or testicular hyaluronidase revealed that the matrix of the myxoid tissue contained hyaluronic acid and chondroitin sulphate. Special fixation was used for ultrastructural preservation of the myxoid matrix, and its ultrastructural appearance was that of these glycosaminoglycans. The previous appellations of microcystic or vacuolated meningioma applied to this type of meningioma relate apparently to poor preservation of myxoid tissue.
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