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.

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.

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.

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.

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.

Ameloblastoma: presentación de un enfermo y revisión de la literatura / Ameloblastoma. Case presentation and review of the litterature

El ameloblastoma se origina de la lámina dentaria o de sus derivados, es un tumor localmente invasor, el más agresivo y frecuente de los tumores odontogénicos. Es de crecimiento lento que invade localmente, con una alta tendencia a la recidiva. Puede ser periférico o intraósea, que es el más frecuente. El periférico es menos agresivo e invasor y con una tendencia a la recidiva. Presenta un patrón histológico variado siendo los más comunes el folicular y el plexiforme. Las formas foliculares con más recidivantes que los plexiformes y las multioculares más que las uniloculares. Radiológicamente es una lesión radiolúcida, quística que se extiende de la región molar hasta la porción superior de la rama mandibular, con multilocularidad, variación en el tamaño de las loculaciones, expansión de la cortical, bordes bien definidos y resorción de las raíces dentales. Su incidencia alta de recidiva y lo complejo de las estructuras faciales que afectan hace que su abordaje terapeútico deba realizarse con base en un criterio médico multidisciplinario

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]. / Linfoma non Hodgkin primitivo della mandibola: descrizione di un caso clinico e revisione della letteratura.

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]. / Plasmocitoma óseo solitario de mandíbula. Presentación de un caso y revisión de la literatura.

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.