Myxoma of the mandible--a fibroblastic tumor

The orosomucoid 1 protein (α1 acid glycoprotein) is overexpressed in odontogenic myxoma

BACKGROUND

Odontogenic myxoma (OM) is a benign, but locally invasive, neoplasm occurring in the jaws. However, the molecules implicated in its development are unknown. OM as well as Dental Follicle (DF), an odontogenic tissue surrounding the enamel organ, is derived from ectomesenchymal/mesencyhmal elements. To identify some protein that could participate in the development of this neoplasm, total proteins from OM were separated by two-dimensional electrophoresis and the profiles were compared with those obtained from DF, used as a control.

RESULTS

We identified eight proteins with differential expression; two of them were downregulated and six upregulated in OM. A spot consistently overexpressed in odontogenic myxoma, with a molecular weight of 44-kDa and a pI of 3.5 was identified as the orosomucoid 1 protein. Western blot experiments confirmed the overexpression of this protein in odontogenic myxoma and immunohistochemical assays showed that this protein was mainly located in the cytoplasm of stellate and spindle-shaped cells of this neoplasm.

CONCLUSION

Orosomucoid 1, which belongs to a group of acute-phase proteins, may play a role in the modulation of the immune system and possibly it influences the development of OM.

Odontogenic myxoma: clinico-pathological, immunohistochemical and ultrastructural findings of a multicentric series

The aim of this study was to analyze the clinico-pathological and immunohistochemical features of 62 cases of odontogenic myxoma (OM) diagnosed in three Oral Pathology Diagnostic Services in Latin America, as well as to describe the ultrastructural features of three of these cases. OM showed a wide age range (9-71 years), with a mean of 27.97 yr (SD: 11.01) and a male to female ratio of 1:2.2. Mandible was affected in 37 cases (59.6%) and maxilla in 25 (40.4%), with 61.3% located in the posterior region. Thirty-nine cases (62.9%) were multilocular and 23 (37.1%) unilocular. Size ranged from 1 to 13 cm, (mean: 5.2 cm). Thirty-seven multilocular (54.8%) and 6 unilocular lesions (26%) were larger than 4 cm (p<0.05). Epithelial islands were identified in 5 cases (8%) on H&E stained sections, but AE1/AE3 and CK14 disclosed these structures in 15 cases each (24.2%); CK5 was positive in 8 (12.9%); CK7 in 2 (3.2%) and CK19 in only 3 cases (4.8%). All cases were negative for CKs 8 and 18, S-100 protein, NSE and CD68, and showed a low index of expression of Bcl2 and ki-67 proteins (<1%). Mast cell antibodies showed these cells in 45 cases (72.6%). Myofibroblastic differentiation evidenced by myofilaments and fibronexi was found in one case out of the three studied by TEM and 29 cases (46.7%) were positive by immunohistochemistry for alpha actin. In conclusion, only a minority of OM had epithelial islands, and only 3 cases expressed CK 19, indicating an odontogenic epithelium origin. Immunohistochemical and ultrastructural findings suggest that OM is a mesenchymal neoplasm in which several factors may contribute to its pathogenesis, including myofibroblastic differentiation and the participation of mast cell products. However, further investigations are needed to better understand the participation of these elements in this particular neoplasm.

Nestin expression in odontoblasts and odontogenic ectomesenchymal tissue of odontogenic tumours

BACKGROUND

Nestin, one of the intermediate filaments constituting the cytoskeleton, is a marker of neural stem cells or progenitor cells. Its expression is also related to tooth development and repair of dentine.

AIMS

The aim of this study was to investigate nestin expression in various odontogenic tumours and evaluate its usefulness for histopathological diagnosis.

METHODS

We studied formalin fixed, paraffin embedded specimens from 129 cases of odontogenic tumours and 9 of mandibular intraosseous myxoma. After characterisation of odontogenic ectomesenchymal tissues in these tumours using antibodies to vimentin, desmin, neurofilament, and glial fibrillary acidic protein, we immunohistochemically examined nestin expression.

RESULTS

No differentiation towards muscle and nervous tissues was found in the odontogenic ectomesenchymal tissues. Although almost all the ameloblastomas and malignant ameloblastomas were negative for nestin, odontogenic ectomesenchyme in the odontogenic mixed tumours demonstrated nestin immunolocalisation, particularly in the region adjacent to the odontogenic epithelium. Odontoblasts and their processes, pulp cells near the positive odontoblasts, and flat cells adhering to the dentine showed immunoreaction with nestin in the odontomas and odontoma-like component in the ameloblastic fibro-odontomas. Neoplastic cells in almost half cases of jaw myxoma and one case of odontogenic fibroma expressed nestin.

CONCLUSIONS

The distribution of nestin in the odontogenic mixed tumours suggests that nestin expression in the odontogenic ectomesenchyme is upregulated by stimulation from odontogenic epithelium. In addition, nestin may also be involved in the differentiation from pulp cells to odontoblasts in odontogenic tumours. Therefore, nestin is a useful marker for the odontogenic ectomesenchyme and odontoblasts in odontogenic tumours. Nestin, one of the intermediate filaments constituting the cytoskeleton, is a marker of neural stem cells or progenitor cells. Its expression is also related to tooth development and repair of dentine.

Myxomas of the head and neck

PURPOSE

Myxomas are rare, locally infiltrative, benign, connective tissue tumors that are found in bone and somatic soft tissues. This article reports our experience with head and neck myxomas and provides a comprehensive literature review.

MATERIALS AND METHODS

Retrospective record review of head and neck myxoma cases seen at 2 tertiary referral centers in Houston, Texas, from 1970 to 1994. Comprehensive literature review and compilation of all myxomas reported in the head and neck.

RESULTS

We identified 7 cases of true head and neck myxoma treated in our centers and identified 169 cases reported in the literature. Most often, myxomas originated in bone (mandible or maxilla) and were most commonly found in adults. All tumors except 1 were treated surgically. Recurrence rates were 6% for local or wide excision and 28% for more conservative surgery such as enucleation or curretage.

CONCLUSIONS

Myxomas of the head and neck should be treated with complete excision of the tumor with clear margins.

Odontogenic myxofibroma arising from the periodontal ligament in the maxillary molar region

A rare case of odontogenic myxofibroma, which arose from the periodontal ligament and expanded into the oral cavity resulting in an epulis-like lesion in a 52-year-old man, is reported including details of studies using lectin histochemistry, transmission electron microscopy (TEM), and immunohistochemistry. Most of the tumor cells, which appeared spindle-like with abundant rough endoplasmic reticulum and some microfilaments by TEM, showed immunoreactivity for mesenchymal markers. Some tumor cells, which were polygonal and contained many microfilaments and some filament bundles, were immunoreactive for muscle markers. The present case was considered to consist of many fibroblasts and some myofibroblasts.

Odontogenic myxoma of the jaws: a clinical, radiologic, immunohistochemical, and ultrastructural study

Ten cases of odontogenic myxoma were evaluated radiologically, histologically, and histochemically. Ultrastructural examination was performed in five cases. Stellate cells with branching processes were seen in an abundant acid mucopolysaccharide background. Occasionally macrophages were found in the tumors. In two cases islands of inactive odontogenic epithelium were identified. The ultrastructural features suggest that many lesional cells are very similar to a myofibroblast. With the avidin-biotin complex immunohistochemical technique, the lesions were tested with antibodies to S- 100 protein, neuron-specific enolase, neurofilaments, glial fibrillary acid protein, keratin, desmin, muscle-specific actin, and vimentin. All the lesions were found to be positive for vimentin and muscle-specific actin, and negative for the rest. The results of our study seem to confirm the muscle-specific actin-positivity of odontogenic myxomas as previously reported.

S100, alpha-smooth muscle actin and cytokeratin 19 immunohistochemistry in odontogenic and soft tissue myxomas

AIMS

To compare the expression of S100 protein, alpha-smooth muscle actin (alpha-SMA) and keratin 19 in odontogenic myxomas and non-odontogenic myxoid lesions.

METHODS

Formalin fixed, paraffin wax embedded tissue from seven odontogenic myxomas, three soft tissue myxomas, six hyperplastic myxoid dental follicles, two intramuscular myxomas, 12 cardiac myxomas, and seven normal dental follicles were examined immunocytochemically for S100 protein, alpha-SMA and cytokeratin 19 using the Streptavidin-biotin method.

RESULTS

A minority of odontogenic myxomas (three of seven) were positive for S100 and the staining was of moderate intensity and in all myxofibroblasts. Soft tissue myxomas, normal dental follicles, intramuscular myxomas, and most enlarged myxoid follicles were negative. In the cardiac myxomas the cells forming cords and islands were positive in approximately half (seven of 12), but the dispersed stellate myxoblasts were positive in only two cases. A population of cells in all the odontogenic myxomas and hyperplastic dental follicles contained alpha-SMA, but such cells were sparse in cardiac myxomas and present in only four cases. Cytokeratin 19 was present in odontogenic epithelium of odontogenic myxoma and follicles.

CONCLUSIONS

A minority of odontogenic myxomas, but not other oral myxoid lesions, may express S100 protein and this could cause difficulty distinguishing myxoma from myxoid nerve sheath tumours. Sparse myofibroblastic cells occurred in all types of myxoma tested. The epithelium sometimes found within jaw myxomas expresses cytokeratin 19 and this is consistent with an odontogenic origin.

Odontogenic myxoma: histochemical and ultrastructural study

Three cases of odontogenic myxoma are presented, two of which were located in the mandible and one in the maxilla. All cases demonstrated similar morphology by light microscopy. Immunohistochemical studies demonstrated positive reaction with antibodies to vimentin and actin, and negative reaction to antibody to S-100 protein. A 127-day-old human tooth bud was used as a control. The ultrastructural features performed on Case 3, when combined with the immunohistochemical findings suggest that the cells comprising odontogenic myxoma are of myofibroblastic origin.

Clear cell sarcoma of the kidney: report of a case with mandibular metastasis simulating a benign myxomatous tumor

The clear cell sarcoma of the kidney (CCSK) is one of the histologically unfavorable types of childhood renal tumors that has a propensity for osseous metastasis. We have presented the clinical and pathologic findings of the first well-documented case of a CCSK with mandibular metastasis, which was recognized approximately 18 months after the original diagnosis. Microscopically, the mandibular lesion had the features of a benign myxomatous neoplasm with the exception of occasional atypical spindle cells. Electron microscopic observation confirmed the undifferentiated nature of the neoplastic cells. It was concluded that the intensive chemotherapy that was administered to our patient very likely affected the histologic appearance of the mandibular metastasis as well as other recurrent lesions in the abdomen. Our review of the literature revealed only five previous examples of Wilms' tumor that had metastasized to the mandible. At least one of these earlier cases also represented a CCSK.

Comparative ultrastructure of soft-tissue myxoid tumors

This comparative analysis of the characteristic ultrastructural features specific for intramuscular myxoma, myxoid liposarcoma, extraskeletal myxoid chondrosarcoma, myxoid malignant fibrous histiocytoma, myxoid variant of dermatofibrosarcoma protuberans, and myxoid neurilemmoma is based on our own studies of 52 cases. In spite of the histologic resemblance frequently observed, these tumors can be easily distinguished on the basis of cytoplasmic and extracellular features by electron microscopy. The value of electron microscopy in the diagnosis of myxoid tumors of soft tissues lies mainly in its potential to provide additional information concerning the cell types involved in the neoplastic process and their line of differentiation.

Resection of a mandibular myxoma via a sagittal ramus osteotomy

A case of myxoma of the mandible is reported in which a sagittal ramus osteotomy was used to gain access to the lesion. This approach appears to have several advantages over more conventional exposures in selected cases.

Glycosaminoglycans in myxoma of the jaw: a biochemical study

Myxoma of the jaw is classified as an odontogenic tumor although final proof for an odontogenic origin is lacking. In the present study glycosaminoglycans (GAG's) in the extracellular matrix of a jaw myxoma were analyzed and compared with known data on GAG's in dental tissues. It was noted that the GAG's formed approximately 1% of the total tumor weight and 17% of the dry weight. Hyaluronic acid formed 72.4% of the GAG-fraction. Neither this high GAG-content nor the high fraction of hyaluronic acid are found in dental tissues and it is concluded that the myxoma matrix differs from the matrix in dental pulp and periodontal ligament.

A case of malignant myxoma (myxosarcoma) of the maxilla

A centrally located maxillary myxoma with malignant histologic appearance and aggressive clinical course is reported in a 40-yr-old man. The gelatinous polypoid tumor mass was diagnosed as a myxoma in the first biopsy. The tumor recurred rapidly (within 3 wk) eroding the bony structures of the maxillary sinus and the hard palate and infiltrating the adjacent soft tissues. In repeated biopsy (as well as reassessment of the first biopsy) the tumor was found to be composed of plump stellate cells, some of which were pleomorphic with atypical and bizarre mitotic figures. The amorphic myxoid matrix contained acid mucopolysaccharides and was completely devoid of lipids. Electron microscopy demonstrated that the tumor cells were identical to fibroblasts, which is consistent with the appearance of myxoma cells. When radiotherapy was unsuccessful, we removed the left maxilla with orbital excenteration and reconstructed the jaw. Three years later the patient died accidentally. At autopsy, no recurrence of myxoma or distant metastases were found. Due to the malignant histologic appearance and the aggressive clinical course, this tumor can be called an odontogenic myxosarcoma and should be added to the WHO classification as a malignant variant of odontogenic myxoma.

Ameloblastic fibrosarcoma of the jaws--report of three cases. Clinico-pathologic, histoenzymological and ultrastructural study

The ameloblastic fibrosarcoma is a rare variety of neoplasm. Three new cases reported here occurred within preexistent benign odontogenic tumors (ameloblastic fibroma or fibro-odontoma). These large, osteolytic tumors, spreading to adjacent soft parts, recurred after surgical treatment in two cases. One of them had a lethal course, with pleuro-pulmonary, mediastinal lymph node and hepatic metastases. Histologically, these sarcomas show a malignant mesenchymal component and few benign ameloblastic islands, which often disappear after one or several recurrences. Histoenzymologically, a high level of alkaline phosphatase and ATPase activities is always present, a feature not present in common fibrosarcomas. The ultrastructural study demonstrates, in analogy with odontogenic myxomas, clear cells provided with numerous microfilaments, secretory cells and also some fibroblasts and myofibroblast-like cells. In addition to these pleomorphic cells, a great number of peculiar granular cells with numerous lysosomal bodies were also found. The histogenesis of these tumors in unknown. Perhaps the epithelial component, being unable to assume its functions of organization, may initiate the malignant transformation of its odontogenic mesenchyme.