Solitary myofibroma of the mandible: an immunohistochemical and ultrastructural study with a review of the literature

A solitary myofibroma (MF) is an unusual spindle cell neoplasm that usually arises in the soft tissue, skin, or bone of the head and neck region in infancy. We report an extremely rare case of MF of the mandible in an 18-year-old Japanese woman together with the conventional histologic, immunohistochemical, and electron microscopic findings. The tumor was well circumscribed and composed of fibroblast-like or myofibroblast-like spindle cells. On immunohistochemical evaluation the tumor cells were positive for vimentin, α-smooth muscle actin, HHF-35, and calponin, but negative for neurogenic antigens and markers for vascular endothelial cells. The Ki-67 labeling index was 10 % and the p53 labeling index was 10 %. Ultrastructural examination revealed smooth muscle cell differentiation. The patient was treated by surgical resection and underwent follow-up without any signs of recurrence. MF presents a wide range of differential diagnosis, including benign and malignant neoplasms. Therefore, accurate diagnosis may avoid an unnecessarily aggressive therapy.

Adenomatoid odontogenic tumour of the mandible

Adenomatoid odontogenic tumour (AOT) is a benign tumour of odontogenic origin. The differential diagnosis of AOT is crucial in terms of surgical management. The 23-year old male patient presented in this case study was referred to the maxillofacial surgery clinic due to the incidental radiological finding of a large osteolytic lesion of the anterior mandible with a retained permanent canine at the base of the bone. Ultrasound imaging revealed the anterior surface of the tooth inside the lesion, indicating extreme thinning of the maintained cortical bone and liquid filling of the cystic lesion. Surgery revealed a bone defect with a deformed, incomplete tooth inside a granulation-like soft tissue. The tooth was extracted and the soft tissues were excavated. Healing was uneventful. Radiographic and physical investigations during long-term follow-up demonstrated complete bone remodeling. Some areas of the tumour were alpha-smooth-muscle-actin positive, indicating a myoepithelial differentiation. Differential diagnosis of AOT to other odontogenic tumours, such as ameloblastoma, is crucial for therapy. Exact morphological diagnosis avoids extensive ablative surgery.

Characterization of the human mandibular osteoblastic osteosarcoma cell line HOSM-2 after long-term culture

We have been subculturing a human mandible-derived osteosarcoma cell line (HOSM-2) for approximately 15 years, and have compared the characters of early generations, which did not exhibit tumorigenicity, to those in the later generations. The shape and doubling time of the cells did not change during long-term culture. The number of chromosomes, however, changed from 59-81 in the 6th generation (modal number: 70) to 54-59 (modal number: 56 and 57), and the chromosomal structure also changed. In addition, the cell line in the later generations showed tumorigenicity in nude mice, and Codon 306 of the p53 gene was mutated to a stop codon due to a point mutation. HOSM-2 cells expressed osteoblast markers, thus confirming them to be osteoblastic osteosarcoma cells. These results showed that changes in certain genes in the HOSM-2 cells led to tumorigenicity in nude mice following long-term culture. In addition, as a mandible-derived cell line with characteristics different from those of limb-derived osteosarcoma cell lines, HOSM-2 cells may be a valuable model for mandibular osteosarcoma and osteoblasts.

Large cell, epithelioid, telangiectatic osteoblastoma: a unique pseudosarcomatous variant of osteoblastoma

A previously undescribed large-cell, epithelioid, and aneurysmal variant of osteoblastoma with minimal osteoid-production--simulating telangiectatic osteosarcoma, epithelioid angiosarcoma, and metastatic carcinoma is reported. The tumor occurred in the mandible of a 14-year-old girl. The light microscopic, immunohistochemical, ultrastructural, cell proliferation, and DNA-ploidy studies, as well as the 7-year disease-free follow-up period all indicate a benign osteoblastic tumor. Cytogenetically, the tumor had a pseudodiploid karyotype, distinguished by a complex t(1;5;17;22) and a terminal 1q deletion. Recognition of this unique, pseudomalignant variant of osteoblastoma is important to avoid an erroneous diagnosis of malignancy.

Initiation of ectopic epithelial calcification in a calcifying odontogenic cyst

Ultrastructural observation was performed on a calcifying odontogenic cyst (COC) associated with an odontoma and arising in the right mandibular region of an 8-year-old Japanese boy. Four types of cells were identified in the epithelial layer of the COC. The basal cells were low columnar in shape and contained some intracellular organelles. They were attached to the neighboring cells with a few desmosomes and resembled inner enamel epithelium of the normal enamel organ. The stellate reticulum-like cells, polygonal in shape, possessed desmosomes and many cytoplasmic projections. Some intracellular organelles and a few bundles of tonofilaments were observed in the cytoplasm. The light oval cells that were pale staining with toluidine blue contained dilated membranous organelles and many relatively evenly distributed tonofilaments. These cells were usually scattered in the vicinity of the focal accumulations of ghost cells, and the cell membrane was discontinuous in parts. The ghost cells contained many bundles of tonofilaments that were 60-240 nm in diameter and arranged in various directions. No intact intracellular organelles were noted in the cytoplasm. They were attached to the neighboring ghost cells with some desmosomes and their cell membrane was discontinuous in parts. A variety of vesicles, 90-450 nm in diameter, were scattered among the tonofilament bundles. Some of these contained needle-like crystals that were considered to be initial calcification sites in ghost cells. These vesicles presented morphological similarities to matrix vesicles, and it is therefore suggested that matrix vesicle-like structures are deeply involved with initiation of calcification of ghost cells in COC.

Establishment and characterization of two cell lines derived from canine spontaneous osteosarcoma

Two new canine osteosarcoma cell lines were established. One (OOS) was established from a 10-year-old female maltese dog with mandibular osteosarcoma and the other (HOS) from a 7-year-old male mongrel dog with scapular osteosarcoma. Histopathological types of OOS and HOS were mixed and fibroblastic cell type, respectively. Transmission electron microscopic features of HOS revealed prominent rough endoplasmic reticulum, suggesting higher malignancy comparing to OOS. Doubling time of OOS and HOS were 45.0 +/- 0.5 hr and 42.0 +/- 0.1 hr, respectively. Alkaline phosphatase activities of OOS and HOS were quite low. Histological features of tumor tissues produced by transplantation of these cells into nude mice were identical to those of original osteosarcomas.

Clear cell odontogenic tumour: a case with induction of dentin-like structures?

A case of clear cell odontogenic tumour, which occurred centrally in the mandible of a 56-year-old Japanese woman, is reported with its histochemical, immunohistochemical and ultrastructural findings. Histologically, the tumour nests were composed of large glycogen-rich clear cells and small non-clear polygonal cells and were separated by thin mature fibrous connective tissue septae. Immunohistochemically, both types of tumour cells showed positive expression of various cytokeratins, in particular cytokeratin 19, and of epithelial membrane antigen. Eosinophilic hyaline deposits and possible dentin-like structures were occasionally formed in contact with the epithelial nests and are regarded as indicative of the epithelial-mesenchymal inductive capacity of this tumour. The aggressive nature of the present tumour was assumed through its invasive growth pattern and occasional mitotic figures. Although it was diagnosed as clear cell odontogenic tumour according to the present WHO classification, the patient must be followed carefully because of its probable malignant nature.

Chondromyxoid fibroma of the jaws. Case report and review of the literature

Chondromyxoid fibroma is a benign tumor of bone that is characterized by chondroid and myxoid differentiation and by ultrastructural and immunohistochemical evidence of chondral origin. It is rare in the jaws and skull bones, where only about 2% of all cases have been reported. A review of the 20 acceptable gnathic cases in the literature and of the current case revealed both a higher incidence in the mandible (76%) than in the maxilla (24%) and an equal sex distribution. The sites of occurrence in both jaws are compatible with origin from developmental cartilaginous remnants. The controversies regarding malignant transformation and therapeutic approach are addressed.

Leiomyoma of the mandible: a rapid growing case with immunohistochemical and electron microscopic observations

A rare case of leiomyoma of the mandible is reported together with the conventional histologic, immunohistochemical, and electron microscopic findings. On immunohistochemical evaluation the tumor cells were positive for vimentin, desmin, and alpha-smooth muscle actin but negative for neurogenic antigens and markers for vascular endothelial cells. Ultrastructural examination revealed smooth muscle cell differentiation. The Ki-67 labeling index was 4.7%. The tumor showed rapid increase in size and clinical features suggestive of malignancy. However, on histopathologic evaluation it was diagnosed as a benign neoplasm, and this diagnosis was supported by the results for mitotic rate, Ki-67 labeling index, and p53 immunostaining.

[Primary non-Hodgkin's lymphoma of the mandible: a description of a clinical case and review of literature]

The authors present a rare case of primary non-Hodgkin lymphoma (NHL) of the mandible in an 81-year old woman. The location of this NHL caused problems in making a differential diagnosis between periodontal and tumoral disease as they have similar symptoms (i.e. dental pain, swelling, ulceration and radiologically detected rarefaction). The present work emphasizes how important correct diagnosis and staging of the primary NHL are to good therapy. The patient was treated with a combination of chemotherapy and radiotherapy and is alive and disease-free 12 months after treatment.

Calcifying epithelial odontogenic tumours in small domesticated carnivores: histological, immunohistochemical and electron microscopical studies

Histological, immunohistochemical and electron microscopical studies revealed one feline and four canine calcifying epithelial odontogenic tumours in 115 oral tumours over a 10-year period. The tumours consisted of islands and sheets of odontogenic epithelium of varying size within a stroma of fibrous connective tissues. The tumour cells were pleomorphic with variable amounts of eosinophilic cytoplasm and large hyperchromatic, polymorphic nuclei with prominent nucleoli. Clusters of keratinized tumour cells ("shadow cells") were frequently seen within the islands and sheets. The multiple spherules of homogeneous eosinophilic material stained positively with Congo red and Dylon stains and produced an apple green birefringence under polarization microscopy, indicative of amyloid. Mineralized foci were scattered throughout the tumour masses and in the homogeneous spherules. Immunohistochemically, the tumour cells reacted with anti-human keratin antibody, but not with anti-human vimentin or anti-chicken desmin antibodies. The homogeneous spherules did not react with anti-human keratin, anti-human vimentin, anti-chicken desmin, anti-amyloid A, anti-laminin or anti-human collagen (type I, III, IV) antibodies. Ultrastructurally, the cytoplasm of tumour cells was abundant and contained a large number of electron-dense bundles of tonofilaments. The homogeneous spherules consisted of fine filaments measuring about 10-12 nm in diameter.

Melanotic neuroectodermal tumour of infancy: an immunohistochemical and ultrastructural study

Two cases of melanotic neuro-ectodermal tumour of infancy (MNTI)--a rare neoplasm arising in the first year of life--are reported, with the results of immunohistochemical and ultrastructural examination. The tumours consisted of a biphasic cell population in a fibrous stroma. The small, darkly staining cells comprising the first population stained positively for synaptophysin, showing them to be neuroblasts, and the large epithelioid cells comprising the second cell population stained positively with the antibodies HMB-45 and NKI-Beteb, showing them to be melanocytes. Ultrastructural examination of the second case confirmed the biphasic nature of the tumour cells, with secretory granules and neurofilaments in the neuroblastic population, and melanosomes in the epithelioid population. These results add to the evidence supporting the neural crest origin of MNTI and confirm its formation from two distinct cell lines. Both cases have responded to local excision, with no recurrence more than a year after initial treatment.

[Solitary plasmocytoma of the mandible. Report of one case and review of the literature]

Between the plasma-cell neoplasms the solitary osseous plasmocitoma represents a low percentage of the whole totality. Unlike the multiple myeloma the plasmocytoma is a lesion potencially curable. The diagnose criteria that must fulfil these lesions are detailed. The AA. report a case sitting in the lower jaw. Review of the previous 28 cases communicated in the anglo-saxon literature. Special attention is paid to the radiotherapy on this sickness.

Biological and morphological characteristics of a transplanted cartilaginous tumor derived from a human osteogenic sarcoma

A cartilaginous tumor derived from a human osteogenic sarcoma of the mandible has been maintained by serial passage to nude mice. Tumor growth was multilobular. Radiopaque spots were seen scattered throughout the tumor at three months after transplantation. Both light and electron microscopic examination at three months revealed that the tumor contained cartilaginous cells at various stages of differentiation. There was metachromasia throughout tumor lobules except in the marginal region. Von Kossa staining was positive in the central region. Ultrastructural study identified four subtypes of chondrocytic cells of a neoplastic nature. In the extracellular matrix around hypertrophic cells, matrix vesicles were observed with mineral deposits. Alkaline phosphatase was found on the plasma membrane and Golgi complexes of hypertrophic cells, and on matrix vesicles. Thus cell lineage and the manner of calcification of the transplanted tumor were similar to those of epiphyseal growth cartilage.

Experimental odontomas in osteopetrotic op/op rats

Osteopetrosis is an autosomal recessive disease in several mammalian species. Osteopetrotic op/op rats suffer from complete failure of tooth eruption related to reduced bone resorption. In our earlier studies, op/op rats grafted with bone marrow cells 3 days after birth were cured of the disease and their molar eruption was restored. However, the incisors failed to erupt and their proliferating ends were distorted, forming odontomas. The purpose of the present investigation was to study the odontogenic tissues in the odontomas, using the correlated techniques of radiography and microradiography of undecalcified material, together with histology of decalcified material and scanning electron microscopy.

Observations on the enamel of odontomas

The morphological study of odontomas provides an alternative model for observing the formation of dental tissues, since different maturing stages are present simultaneously. Investigations were performed on decalcified samples (using light microscopy and transmission electron microscopy) and on undecalcified samples of complex odontoma enamel (using transmission electron microscopy). Simultaneous presence of prismatic enamel at various maturing stages with different structural characteristics was observed. Such enamel was sometimes associated with layers of ameloblastic cells with characteristics of cells in functional activity. In other sites, the enamel did not present a prismatic structure but it appeared as unstructured material clusters with abundant organic component. It was concluded that the theory according to which an ecto-mesenchymal inductive failure occurs in odontomas is not confirmed. The defect seen at the beginning of the differentiated and anomalous tissue maturation may be related to latest events in the development of the enamel organ. In this regard, it was concluded that such events involve the efficiency of the ameloblasts and the possible alterations in the organic matrix.

Clear cell odontogenic carcinoma. A case report with massive invasion of neighboring organs and lymph node metastasis

Clear cell odontogenic carcinoma is a rare and unusual tumor that occurs in the jaws. This tumor is generally considered to be of a low grade of malignancy. We describe a patient with a huge clear cell odontogenic carcinoma that originated in the mandible and exhibited massive invasion into the adjacent tissues and metastases to the submandibular lymph nodes. The ultrastructural and immunohistochemical details are described.

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.

Meningioma of the mandible

This is the first case report to the authors' knowledge of a primary extracranial meningioma located in the mandible. Ultrastructurally, the tumor cells had intricate cellular membranes and desmosome-like attachment structures. Using immunohistochemical analysis, the tumor expressed both epithelial membrane antigen and vimentin. Although the origin of extracranial meningiomas has been attributed to proliferation of ectopic embryonal nests of arachnoidal cells, the proliferation of perineural cells of peripheral nerves also is possible as a result of the structural and functional similarities of perineural cell and arachnoid cells. The authors suggest that extracranial meningiomas may be more common than published reports indicate because of certain histologic similarities between these tumors, neurilemomas, and solitary neurofibromas.

Central granular cell tumor of the jaw. An electron microscopic and immunohistochemical study

Central granular cell tumor of the jaw was formerly known as granular cell ameloblastic fibroma; recently, the term central granular cell odontogenic fibroma has been proposed. This study attempts to determine the ultrastructural features and selected immunohistochemical properties of the tumor cells. Four formalin-fixed specimens were processed for electron microscopy, and for immunohistochemical staining with antiactin, anti-glial fibrillary acidic protein, and OKT6 (CD1) with the avidin-biotin-peroxidase complex method. Tumor cells contained many primary lysosomes, autophagic vacuoles, and phagocytic vacuoles. The phagocytic vacuoles appeared to contain collagen fibrils. Tumor cells stained positive with antiactin and OKT6 (CD1), and negative with anti-glial fibrillary acidic protein. The results indicate that tumor cells are actively phagocytic and suggest that tumor cells might arise from Langerhans' cells.

An electron and optical microscopic study of juxtaposed odontogenic keratocyst and carcinoma

Odontogenic keratocyst and squamous cell carcinoma commonly occur within the oral cavity; however, the juxtaposition of these lesions is rare. The light microscopic and ultrastructural features of such an event are reported. Although some morphologic similarities between the cyst and tumor were observed, definitive evidence of a common origin was not obtained.

Melanotic neuroectodermal tumor of infancy. A reexamination of a histogenetic problem based on immunohistochemical, flow cytometric, and ultrastructural study of 10 cases

Ten cases of melanotic neuroectodermal tumor of infancy (MNTI) were studied. There were nine males and one female ranging in age from 2 weeks to 10 months; one patient was 8 years old. Sites of origin were the maxilla (five), epididymis (two), mandible (one), skull (one), and soft tissues of the cheek (one). Six tumors recurred from 1 to 18 months after diagnosis. One patient had widespread dissemination. Electron microscopic study of four cases showed cells with melanosomes at various stages of maturation, and cells with neuroblastic features, including neurosecretory granules and cytoplasmic processes. Nine cases of MNTI were studied immunohistochemically. Small neuroblastic cells and large cells in all cases were reactive for neuron-specific enolase (NSE), synaptophysin, HMB45, and dopamine-beta-hydroxylase, large cells in all cases and few small cells were reactive for cytokeratin (CK) and vimentin (VIM). Epithelial membrane antigen was observed in large cells in three cases, four cases expressed Leu 7 antigen, three were focally positive for glial fibrillary acidic protein, one for desmin, and one for chromogranin. All cases were nonreactive for retinol-binding protein, neurofilaments, alpha-fetoprotein, S-100 protein, and carcinoembryonic antigen. Five normal adult retinas were studied similarly; the pigmented epithelium of the retina was reactive for CK, VIM, HMB45, NSE, and S-100. DNA study, performed in eight tumors, revealed aneuploidy in two (DNA index = 1.7 and 1.8); these cases recurred within 1 month. No differences were observed according to site or behavior. MNTI is a primitive neuroectodermal tumor with polyphenotypic expression of neural and epithelial markers, melanin production, occasional glial, and rhabdomyoblastic differentiation, and no photoreceptor differentiation. It probably represents a dysembryogenetic neoplasm that recapitulates the retina at 5 weeks of gestation.

Eosinophilic granuloma showing rapid regression. Report of a mandibular case with application of a modified PNA staining method for demonstration of Langerhans-type histiocytes

A mandibular eosinophilic granuloma in a 16-year-old male is reported. This case showed rapid regression, which was clearly demonstrated by histopathological examinations of both preoperative biopsy and surgical materials. Transformation from an eosinophilic granuloma to a xanthomatous granuloma with multinucleated giant cells was observed after only 26 days. Special staining of paraffin sections with peanut agglutinin (PNA) and use of electron microscopy showed that the main component of the lesion in the biopsy material was Langerhans-type histiocytes. These cells had disappeared from the lesion by the time of the operation. At the same time, the number of infiltrating eosinophils was also markedly reduced. It seems appropriate to consider that the rapid regression of this disease was correlated with the rapid reduction in the number of Langerhans-type histiocytes appearing in the granulomatous foci, as well as the number of infiltrating eosinophils.

A case of neurofibrosarcoma associated with neurofibromatosis: light microscopic, ultrastructural, immunohistochemical and biochemical investigations

A case of neurofibrosarcoma (NFS) with neurofibromatosis was studied by light microscopic, ultrastructural, immunohistochemical and biochemical methods. Histologically, spindle-shaped tumor cells with atypical hyperchromatic nuclei were arranged in a fascicular or sheet-like fashion. Electron microscopic examination revealed discontinuous basement membrane-like structures. Immunohistochemical study revealed S100 protein alpha chains in tumor cells. A biochemical analysis showed large amounts of gangliosides (sialic acid 13.5 micrograms/g wet tissue weight) in tumors. GM3 and GD3 were the major components; these results were compatible with the NFS ganglioside patterns found in our previous study. Results confirmed the diagnosis of NFS and indicate that NFS clearly has some neuroectodermal characteristics and that Schwann cells may possibly be related to its origin.

[The ultrastructure of ameloblastoma]

The ultrastructural features of five mandibular ameloblastomas were investigated. The morphological comparison between ameloblastoma and enamel organ was made, and the cause of the appearance of granular cells in the tumor was discussed. The peripheral columnar cells were morphologically similar to the inner enamel epithelium of the enamel organ. The central cells were similar to the stellate reticulum cells. There were not stratum intermedium-like cells in the tumors. This implied that the tumors were developed earlier than the enamel organ of bell stage. The squamous cells were sometimes found in the central part of the tumor cell masses. These cells were flat with a few organelles in the plasma, but had a lot of tonofilaments. This suggested that these cells were not active. Upon the ultrastructure, however, it could not be determined whether the appearance of these cells reflected a low differentiation or a degeneracy. Granular cells contained a lot of lysosomes, but no autophage was noticed. We thought that the appearance of these cells was due to accumulation of some unusual substances in the cells, the substances might be related with the glycosaminoglycan.

Dentin formation in so-called "fibro-osteo-cemental" lesions of the jaw: histologic, electron microscopic, and immunohistochemical investigations

Two cases of the so-called fibro-osteo-cemental lesions of the jaws, containing unusual deposits of hard tissue, are described. There were peculiar spheroid calcifications or larger masses forming small cavities with a radial arrangement and discontinuous blasts extending with axonlike cell processes toward an acellular core. For further definition, electron microscopic and immunohistologic studies were done. The most conspicuous features were abundant intracytoplasmic vimentin filaments in the blasts, tight junctions, matrix vesicle formation, a globular accretion pattern, and so-called matrix maturation. These findings militate against an osseous or cementous nature of this hard tissue. Rather, both the light and electron microscopic findings are highly compatible with the assumption that the blasts are odontoblasts and that an immature type of dentin is formed. In addition to fibroblasts, osteoblasts, and cementoblasts, apparently also a further descendant of the ectomesenchyme--the odontoblasts with dentin formation--may participate in the so-called fibro-osteo-cemental lesions.

Patterns of spread of squamous cell carcinoma within the mandible

The patterns of spread of squamous cell carcinoma within the mandible were investigated in 43 nonirradiated (33 edentulous and 10 partially dentate) and 16 irradiated mandibles. Two modes of spread were identified: (1) spread in relation to the inferior alveolar nerve, and (2) spread in spaces between cancellous bony trabeculae. Although nerve-related spread was significantly more frequent in the edentulous than in the partially dentate nonirradiated mandible, the difference in incidence between all nonirradiated mandibles and irradiated mandibles was not significant. The patterns of spread in cancellous bone in irradiated and nonirradiated mandibles differed little. Spread of tumor within the medulla, deep to an intact cortex beyond the extent of extraosseous soft tissue tumor, was seen infrequently.

Giant cell reaction to ameloblastoma: an immunohistochemical and ultrastructural study of a case

Histopathologic, immunohistochemical, and ultrastructural features of the giant cells appearing in the tissue surrounding an ameloblastoma are presented. These giant cells exhibited strong activity of a highly stable form of acid phosphatase, and were positive for alpha-1-antichymotrypsin. Ultrastructurally, the cytoplasm of the giant cells contained numerous mitochondria, and the cell membrane was comparatively smooth. Therefore, it is proposed that these multinucleated giant cells are reactive to the invasion of ameloblastoma and are histiocytic in origin.

Melanotic neuroectodermal tumour of infancy (MNTI). Immunohistochemical and ultrastructural study of a case

A case of melanotic neuroectodermal tumour of infancy (MNTI) which occurred in the left lower jaw of a 15-months old child was studied by electron microscopy and immunohistochemical methods to verify the neural crest origin of this tumour. Two cell population were observed: pigment melanocyte-like cells and non-pigmented nerve-like cells. Immunohistochemical analysis with neuron-specific enolase (NSE) and S-100 protein visualized two cell subtypes in the non-pigmented cell population. The combined ultrastructural findings and immunohistochemical data confirm the neural crest origin of MNTI.

Immunohistochemical staining for vimentin filaments and S-100 protein in myxoma of the jaws

Two jaw myxomas have been analyzed by a panel of antibodies to characterize this tumour type. Vimentin, but not keratin, neuron-specific enolase (NSE), glial fibrillary acidic protein (GFAP), neurofilament (NF), desmin and Factor VIII-related antigen (FVIII-AG), demonstrated positivity in the cytoplasm of the neoplastic cells. Moreover, an antibody against S-100 protein also showed a strong positive reaction in the cytoplasm of the tumour cells examined. Thus directly indicating a mesenchymal derivation for odontogenic myxoma, and is the first demonstration of S-100 protein within the cells of this tumour type.

Ameloblastic fibrosarcoma of the right mandible: immunohistochemical and electron microscopical investigations on one case, and a review of the literature

A case of a 7-year-old girl with ameloblastic fibrosarcoma of the right mandible is described. Immunohistochemical techniques (detection of intermediate filaments, tissue polypeptide antigen, lactoferrin, lysozyme, Factor VIII-related protein, S-100 protein, carcinoembryonic antigen, alpha-foeto-protein, "lectin-receptors") and electron microscopy were applied. The epithelial part of the tumor, which was positive for keratin, showed distinct tonofilaments in electron microscopy. In contrast, the mesenchymal part was vimentin positive. The cells displayed the ultrastructural features of fibroblasts. The observations are compared with those reported in the literature.

An immunohistochemical and electron microscopic study of a central venous hemangioma of the mandible

To date, 96 cases of central hemangiomas of the jawbones have been described in the literature. Of these cases, the mandible has been more affected than the maxilla, while approximately 50% of all cases occur in the first and second decades of life. Histopathologically, cavernous and capillary types are often found, in contrast to the central venous type, which is rare. We have recently treated a 44-year-old man, who was found to have a central venous hemangioma in his mandible. Immunohistochemical studies were performed using factor-VIII-related antigen as well as various lectins as markers for tumor endothelial cells. Our results showed that four kinds of lectins (UEA-I, PNA, ConA, and DBA) were useful for the marker as factor-VIII-related antigen. Scanning electron microscopic findings of this tumor demonstrated that the lumina of the blood vessels were more rough, while the lining endothelial cells were more irregular when compared with those of the normal vascular system.

Desmoplastic fibroma involving the mandible

Desmoplastic fibroma is a rare, benign, fibroblastic tumour arising intra-osseously. A case in a 13 year-old male is described. A tumour, situated between the roots of the right mandibular canine and premolar, was excised in 1984. Morphologically, the characteristics of the tumour conformed well to those of a desmoplastic fibroma. The differential diagnosis of desmoplastic fibroma with reference to the histopathological and ultrastructural appearance of the tumour is discussed.

Malignant schwannoma of the mandible

A case of malignant schwannoma occurring in the mandible of a 76-year-old Japanese woman is presented. Results of the gross examination are described as well as the surgical procedure. Details of the staining techniques for examination of the biopsy specimen are given. The histopathological findings are mentioned including those obtained from radiographic, microscopic, and electron microscopic examination. A discussion of the disease and of its difficulty of diagnosis follows.

Telangiectatic osteosarcoma of the mandible

A telangiectatic variant of osteosarcoma of the mandible was seen in a 15-year-old Chinese girl. It was first diagnosed as an aneurysmal bone cyst both radiologically and pathologically. There were local recurrences despite repeated surgery, and subsequent response to chemotherapy and radiotherapy was poor. The patient died 16 months later with direct cerebral invasion, but no distant metastases. Diagnostic and clinicopathologic correlative aspects of this tumor variant are discussed, but more study of this tumor variant in the jaw is needed because this is probably the first case fully reported.

Mandibular vascular leiomyoma

A 54-year-old man had a symptomless swelling on the buccal aspect of the right mandibular molar area, this was associated with a multilocular radiolucency. Histologic and ultrastructural examination of the lesion revealed a vascular leiomyoma. This is only the fourth intrabony leiomyoma of the jaws to be reported.

Granulocytic sarcoma of the mandible

The case is presented of a 54-year-old black man with a mass apparently involving only the soft tissue retromolar trigone on panoramic and mandibular series radiographs. A granulocytic sarcoma involving the mandible was diagnosed on biopsy with the aid of histochemical stains, immunologic cell surface markers, and electron microscopy. The autopsy also revealed involvement of the ribs and liver.

Chondromyxoid fibroma

A brief review of the literature concerning chondromyxoid fibroma is presented. 7 previous cases and the present case of the tumor in the jaws are described. Parallels to the extra oral lesions are drawn and in the light of previously published data, distinctive diagnostic features are discussed. The importance of close cooperation between the surgeon, the radiologist and the pathologist is stressed to avoid a misdiagnosis and radical treatment of the malignant counterpart of a rare benign tumor.

Ameloblastoma in childhood

Clinical, radiologic, and histologic studies were performed in eight cases of ameloblastoma in patients younger than 16 years of age. The mean age of the patients was 10.8 years, equal numbers of males and females were affected, and the most common location was the lower molar and ramus areas. Radiologically, a monocystic osteolytic image was observed in all cases. Histologically, two forms of growth were observed: an intramural, infiltrating, plexiform or follicular type, and a polypoid type, prolapsing toward the lumen of a cystic cavity. The ameloblastomas recurred in three cases a year after surgery.

Intracytoplasmic crystalloids in granular cell ameloblastoma

A case of granular cell ameloblastoma with numerous intracytoplasmic crystalloids is reported. The intracytoplasmic crystalloids are linear in shape and up to 15 microns in length, and stained similar to the intracytoplasmic granules of granular cell ameloblastomas which have been identified histochemically as lysosomes. The intracytoplasmic crystalloids in the granular cell ameloblastoma presented here probably reflect a variant type of lysosome, possibly due to cellular degeneration.

Ameloblastoma with myofibroblasts: first report

A recurrent infiltrative ameloblastoma of the mandible with a predominantly "follicular pattern" of the epithelial component is studied. The stroma contains abundant myofibroblasts; these cells have been described in benign and malignant infiltrative processes. This raises the question of the relationship between the presence of myofibroblasts and the aggressive behavior of a neoplasm.