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At least 19 recordsLinked to original sources
PubMed1977

Malignant myoepithelioma of the parotid gland.

Myoepithelial cells are a significant component of most types of salivary gland neoplasms. A small but increasing number of case reports have also shown that pure myoepitheliomas form a distinct class of neoplasms with unique histological features. Previously reported cases have been either benign or, at most, locally aggressive. We present here a case of a malignant myoepithelioma of the parotid gland, confirmed by electron microscopy, that was locally aggressive and eventually metastasized. Review of this case and of existing reports indicates that myoepitheliomas exhibit a wide range of biological behavior that seems to correlate with their histological appearance.

Aged↗
PubMed1976

Myoepithelioma. Review of the literature and report of a case with ultrastructural confirmation.

The myoepithelioma is a rare salivary gland tumor composed nearly exclusively of myoepithelial cells. A case occurring on the palate of a 22-year-old man is reported. Electron microscopic findings of occasional desmosomes, a basal lamina associated with the plasma memb;rane, and perinuclear cytoplasmic filaments confirmed the diagnosis. The myoepithelioma appears to resemble the pleomorphic adenoma clinically and may be a development variant of the pleomorphic adenoma.

Adenoma, Pleomorphic↗
PubMed1975

Myoepithelioma of minor salivary gland origin. Light and electron microscopical study.

A gingival tumor that invaded the anterior maxilla was removed from a 14-year-old boy and studied by light and electron microscopy. The tumor was composed exclusively of myoepithelial cells and appeared to be malignant. By light microscopy, the tumor appeared to be a poorly differentiated epithelial neoplasm of undetermined origin; however, electron microscopical examination showed myoepithelial differentiation, indicative of a salivary gland origin. To our knowledge, the present case represents the only confirmed myoepithelioma that shows features indicative of malignant potential. Myoepitheliomas may be related to mixed tumors of salivary glands.

Adolescent↗
PubMed2026

Myoepithelioma-like tumor of the vulvar region shows a quiet genome and heterogeneous detectable mechanisms of SMARCB1 inactivation: Integrated analysis of two cases and review of the literature.

Myoepithelioma-like tumor of the vulvar region (MELTVR) is a rare SMARCB1-deficient mesenchymal neoplasm of adult women that can mimic malignant vulvar sarcomas, particularly epithelioid sarcoma. Although loss of SMARCB1/INI1 expression is a defining feature, the comprehensive genomic landscape of MELTVR remains poorly characterized. We report two cases of MELTVR and performed integrated histopathologic, immunophenotypic, and molecular analyses, including whole-exome sequencing (WES) with copy number assessment and targeted RNA-based fusion testing using the Archer FusionPlex Sarcoma panel. Histologically, both tumors consisted of relatively uniform epithelioid to short spindle cells in solid nests and cords within focal myxoid stroma, with complete loss of INI1 and positivity for smooth muscle markers and focal ER/EMA expression. Genomic profiling demonstrated a quiet molecular background in both cases, with low tumor mutation burden (0.45 and 1.03 mut/Mb) and no pathogenic SNVs/indels in major cancer-associated genes. One case showed a focal homozygous deletion of the SMARCB1 locus at 22q11.2, whereas the other case exhibited INI1 loss without detectable SMARCB1 mutation or copy number loss, suggesting heterogeneous mechanisms of inactivation. CDKN2A copy number remained neutral in both tumors. No canonical sarcoma-associated gene rearrangements, including EWSR1, FUS, PLAG1, or NR4A3, were identified. Together with a review of previously reported cases, these findings support MELTVR as an SMARCB1-inactivated neoplasm with low genomic complexity and highlight the diagnostic value of NGS-based profiling in excluding malignant mimics and preventing overtreatment.

Humans↗
PubMed1977

Benign human mammary myoepithelioma.

A leiomyoma-like, multifocal tumour developed from intraductal papillomatosis in the breast of a 42 year old woman. The spindle-shaped tumour cells were examined by light, electron and polarizing microscopy, which revealed that they originated from immature "precursor" myoepithelial cells. The author suggests that the tumour be called "myoepithelioma". From the morphological characteristics of the tumour the myoepithelial cells appear to be capable of producing leiomyoma-like benign or malignant tumours. The role that has been attributed by some to the myoepithelial cell in the production of epithelial tumours is problematical, in the light of the present finding.

Adult↗
PubMed1979

A comparision of normal submaxillary gland proteins with proteins obtained from a transplantable murine salivary gland carcinoma (myoepithelioma).

A new transplantable murine salivary gland carcinoma (myoepithelioma) was further characterized by comparing total protein patterns with normal submaxillary gland proteins. Analysis by isoelectric focussing or by labelling studies with radioactive leucine showed considerable differences between tumour and normal proteins. In contrast, analysis of staining patterns after electrophoresis in sodium dodecyl sulphate containing gels revealed a striking similarity between normal proteins, tumour proteins and proteins obtained from metastatic growths. It thus appears that tumour proteins closely resemble the normal proteins from the tissue of origin with respect to molecular size as determined by electrophoretic mobility, while significant differences occur in charge and labelling kinetics.

Animals↗
PubMed1977

Transplantable murine salivary gland carcinoma (myoepithelioma). I. Biologic behavior and ultrastructural features.

Three salivary gland adenocarcinomas that arose spontaneously in female BALB/c mice, originally being maintained for plasmacytoma (MOPC) investigations, were studied; only one of the original hosts was MOPC-bearing. The initial carcinomas clearly originated from the salivary gland, not the breast, and did not resemble plasma cell lesions. The submandibular gland was the site of origin in each instance. Lesions were identical to those described previously in strains A and C mice as myoepitheliomas, with intracellular fibrils positive by phosphotungstic acid-hematoxylin (PTAH) stain. Each cell line (A, B, and C) of the salivary gland carcinomas was serially transplanted for 28, 29 and 14 generations, respecitvely. The lesion was easily transplanted, achieved almost 100% takes, and uniformly killed the host in 6-12 weeks, with metastasis to the peritoneum and liver. A myeloproliferative reaction characterized by leukemoid changes regularly occurred during the growth of the tumors. Each transplant generation was identical to its original salivary gland precursor by light and electron microscopy. In their growth pattern, the tumors resembled sarcomas with large areas of spindle cells. Ultrastructurally, the neoplastic cells contained the organelles of acinar and possibly ductal cells and exhibited varying degrees of synthetic and secretory activity, characterized by abundant free ribosomes and granular ergastoplasm, with prominent canaliculi containing abundant secretory material. Numerous desmosomes were seen, as well as coarse filaments and fine fibrils in most tumors cells, particularly in cells exhibiting lesser degrees of secretion. The filaments most likely represented the PTAH-positive intracellular fibrils observed by light microscopy. All tumors had numerous cells with resting features.

Adenocarcinoma↗
PubMed1979

The role of myoepithelial cells in the morphogenesis of induced mammary tumours.

The localization and cytomorphology of myoepithelial (ME) cells and their role in the morphogenesis of the mammary gland tumours of Wistar rats induced by 7,12-Dimethylbenz-a-anthracene-DMBA- were studied. Cells which do not participate in secretion and contain cytoplasmic myofibrillar bundles in a typical arrangement are considered to be of ME origin. In the histogenesis of induced mammary gland tumours no difinite role can be attributed to mature ME cells or their precursors. Decreased differentiation is associated with reduced numbers of ME cells. No ME cells can be detected in the anaplastic, stromafree portions of the solid tumour. The sarcomatous component of the induced carcinosarcomas originates from connective tissue. ME cells may give rise to leiomyoma-like tumours comparable with the human benign mammary myoepithelioma. The atrophic areas of mammary gland tumours consisted mostly of preserved ME cells. The ME cells of induced mammary gland tumours were, in every respect, identical with the normal ME cells of control mammary glands.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1978

Immunohistochemical identification of actomyosin-containing (myoepithelial) cells in non-neoplastic and neoplastic tissues.

Actomyosin-containing cells in both non-neoplastic and neoplastic tissues of the salivary gland, lung, breast and some other organs were studied by immunofluorescent microscopy using antiactomyosin rabbit serum. In the breast, myoepithelial-like cells with positive immunofluorescence in the cytoplasm were observed not only in sclerosing adenosis and fibroadenoma but also in scirrhous and medullary-tubular duct carcinomas. No positive cells were observed in medullary carcinomas with lymphoid infiltration. The actomyosin positive cells were also seen at the outer layer of tubules of "mixed tumors" and of cell nests in adenoid cystic carcinoma and in myoepithelioma of the salivary gland, but not in the metaplastic squamous cells or in the cells of myxomatous and chondroid areas of "mixed tumor". In carcinoma of the lung, actomyosin-positive cells were observed in adenoid cystic carcinomas and adenocarcinoma of the bronchial gland type, but they were not seen in squamous cell carcinomas or papillary adenocarcinomas. It was concluded that the actomysoin-containing cells with structural appearances of myoepithelial cells in a variety of tumors were neoplastic myoepithelial cells.

Actomyosin↗
PubMed1976

Differences in tumor incidence in two substrains of Claude BALB/c (BALB/cfCd) mice, emphasizing renal, mammary, pancreatic, and synovial tumors.

Observations were made on the tumor incidences in two substrains of the BALB/CFCd mouse. A total of 900 mice were examined. They comprised two substrains (families), direct descendants of two different females (designated 916 and 917) of the 31st inbred generation. Offspring of sibling matings of the fourth and fifth generation descendants of these two females were killed when moribund or when they had visible or palpable masses. Complete gross and microscopic examinations were conducted. Renal tumors were noted in 48.1% of those necropsied in family 916 and in 24.6% of those in family 917 (p less than .025). Mammary tumors were found in 13.3% of family 917 and in 3.3% of family 916 (p less than .001). Neoplasms of the reticulo-endothelial system (reticulum cell neoplasms, lymphocytic leukemia, other lymphocytic neoplasms) were found in 20.0% of family 917 but only in 11.2% of family 916 (p less than .005). Tumors of the respiratory system (primarily alveolar adenomas and alveolar adenocarcinomas) were found in 10.2% of family 916 and 16.5% of family 917 (p less than .05). Less commonly observed tumors included synoviomas, 7.6% in family 916 versus 2.1% in 917 (p less than .005), and seven pancreatic acinar adenomas, all but one of which were found in family 916. Also recorded were a total of nine myoepitheliomas, 28 hemangioendotheliomas, two interstitial cell tumors of the testis, a single mesothelioma and a single rhabdomyosarcoma of the esophagus. Degenerative lesions consisting of kyphoscoliosis were noted in 3.7% of mice examined in both families combined.

Adenocarcinoma↗
PubMedDate not supplied

The pathology of head and neck tumors: salivary glands, part 3.

The term adenoma is applied to a rather wide variety of histopathologic entities in the salivary glands. These include tumors derived from the ductal epithelium and/or from myoepithelial cells and other salivary-gland elements, such as the sebaceous glands. Within the categories of mixed tumor (pleomorphic adenoma), monomorphic adenoma, clear-cell tumor, and sebaceous lesions, there are also several subtypes, each of which lends further credence to the germinative potential of the salivary tissues. Presented in this report is a clinicopathologic and histogenetic analysis of these lesions. Specifically discussed are mixed tumor, monomorphic adenoma, carcinoma ex-pleomorphic adenoma, clear-cell tumor, sebaceous lymphadenoma, and sebaceous carcinoma.

Adenoma↗
PubMed1978

Adult renal myoepithelial hamartoma.

A renal myoepithelial hamartoma presented as a lucent filling defect with gross hematuria in an adult female. Preoperative studies caused conflicting impressions. The predominance of smooth muscle and incorporated tubuloepithelial elements characterize the tumor as a hamartoma of myoepithelial type. Pertinent review of the literature confirms the rarity of this lesion in adults.

Adult↗
PubMed1975

Mammary cancer in the dog: a study of 120 cases.

Of the 120 cases of mammary cancer occurring in 117 female dogs (15 spayed), 2 male dogs, and 1 dog of undetermined sex, 107 (nearly 90%) were observed in dogs 8 to 15 years old. Mammary tumors occurred in nearly 14% of 875 female dogs with neoplasms. Nearly 60% of 128 neoplasms were located in the 4th and 5th mammary glands. Of the 128 cancers in these 120 dogs, 85 were classified as duct carcinoma, 38 as lobular carcinoma, 3 as malignant mixed tumor, and 2 as duct and lobular carcinomas. Most duct carcinomas originated in the epithelial cells of ducts at all levels, and a few arose in previously benign duct papillomas. The lobular carcinomas arose in alveoli and developed into progressively larger lobules. A negative factor in the development of mammary cancer is ovariectomy before or shortly after the first estrous cycle in the dog and before the age of 40 in women. In both dog and man, aging is a positive factor in the development of mammary cancer. In women, other positive factors are nulliparity and inheritance; e.g., a high rate of breast cancer in close female relatives of Jewish extraction. An epidemiologic study of breast cancer in man and dog in high-risk countries(e.g., United States) and low-risk countries (e.g., Japan) is indicated.

Animals↗