Expression of connexin 32 and 43 in developing rat submandibular salivary glands

The expression of the gap-junction proteins connexin 32 and 43 in the developing rat submandibular gland was determined using reverse transcription-polymerase chain reaction and immunohistochemistry. Sprague-Dawley rats from the 17th gestational day through to the 28th postnatal day were used. Connexin 43 gene expression was detected on the 17th gestational day. Connexin 32 gene expression was also detected on the 17th gestational day but less intensely. Immunolabelling for connexin 43 was also found in the developing submandibular gland from the 17th gestational day. Prenatally the most immunoreactive areas for connexin 43 were located in the periphery of terminal tubules, but some staining was discernible between the cells in terminal buds. In the postnatal period, reactive areas were located at both the periphery of acinus-like structures and around the intercalated duct. This is consistent with the known association of connexin 43 with myoepithelial cells. Connexin 32 immunostaining was first detected in the developing submandibular glands on the 18th day of prenatal development. Positive staining was present on the lateral side of the proacinar and mature acinar cells. The number of immunoreactive areas per cell increased during early development followed by a significant decrease perinatally. During postnatal development the density of areas again showed a pattern of increase. These results suggest that connexin 43 is associated with growth and differentiation in the pre- and perinatal periods and also with the contractile function of myoepithelial cells in the postnatal period of the developing submandibular gland. It is also implied that the number of connexin 32-positive areas may correspond to an increase or decrease in the number of proacinar and mature acinar cells.

Cell proliferation and death of Hertwig's epithelial root sheath in the rat

Hertwig's epithelial root sheath (HERS) degenerates immediately after root dentin is formed. However, odontogenic tumors or cysts may originate from residual cells, although little is known about how HERS proliferates and disappears. This study investigated whether cell death is provoked in the tissues surrounding the root during eruption of the rat upper molar. We employed the TdT-mediated-dUTP nick end labeling (TUNEL) method and transmission electron microscopy (TEM) to observe the morphological features of cell death. We examined the activity of cell proliferation immunohistochemically using proliferative cell nuclear antigen (PCNA) and the continuity of HERS using polyclonal keratin antibody (PK). Cell death resembling apoptosis and apoptotic bodies phagocytosed by neighboring mesenchymal cells were detected in only a few cells by both TUNEL and TEM. We also found cells with electron-lucent cytoplasm which contained dilated or ruptured mitochondria and remarkably dilated rough endoplasmic reticulum (rER) which lay sparsely along the root. These cells seemed to be dead HERS cells based on their ultrastructural features, location, and stage. PCNA-positive cells were found in the apical end of the HERS cells, fibroblasts of the periodontal ligament, and odontoblasts. PK reacted with HERS; however, PK-positive cells partially disappeared after the 15th postnatal day when the root dentin had formed slightly. These results may indicate that HERS cells migrate into the periodontal ligament or die immediately after root dentin is formed and that various types of cell death such as apoptosis and cytoplasmic type occur in the tissues surrounding the root during tooth development.

Changes in autonomic nervous activity after catheter ablation of right ventricular outflow tract tachycardia

Idiopathic right ventricular outflow tract (RVOT) tachycardia is prone to occur when sympathetic nervous activity increases. The effects of catheter ablation on the arrhythmia may be modified by changes in the sympathovagal balance induced by the ablation. In 8 patients with RVOT tachycardia, analyses of heart rate variability (HRV) were performed before, early (1-3 days, POST1) and late (7-14 days, POST2) after the ablation. From 24-h ambulatory Holter monitoring, RR intervals of a 2-h period during sleep (00.00-06.00 h) were analyzed. MSSD and pNN50 were increased along with a decrease in the frequency of ventricular arrhythmias at both POST1 and POST2 after successful ablation. In contrast, high frequency power (HF) was increased, and low frequency power (LF) and LF/HF were decreased only at POST2 in the 8 patients. In 4 patients in whom the initial ablation had been unsuccessful, the indices of HRV did not change significantly after the unsuccessful ablation, but after successful ablation they changed as in the other 4 patients. After successful catheter ablation of the RVOT tachycardia, sympathetic nervous activity was decreased and parasympathetic nervous activity was increased along with decrease in the frequency of ventricular arrhythmias. The presence of ventricular tachyarrhythmia could, therefore, elicit sympathetic predominance and consequently modify arrhythmogenesis.

Pattern of expression of beta-defensins in oral squamous cell carcinoma

Human beta-defensin (hBD)-1 and hBD-2 are antimicrobial peptides that have been detected in certain types of epithelia, including the skin and oral epithelia. It has been suggested that bacterial infection is an important factor in the process of carcinogenesis. The expression of hBDs in oral squamous cell carcinoma (SCC) may be down-regulated. We studied the pattern of expression of hBD-1 and hBD-2 mRNA in oral (SCC) cell lines and in tumor samples obtained from four patients with oral SCC who underwent surgical resection, by reverse transcription-polymerase chain reaction (RT-PCR). Human gingival epithelial (HGE) cells were used as the control. The effect of various inflammatory cytokines on hBD-1 and hBD-2 expression in the HGE cells and SCC cell lines, was also studied. hBD-1 mRNA was detected in the Ca-9, SCC-9 and HSC-4 cell lines, but not in the SAS and KB cell lines. hBD-2 mRNA was detected in all five cell lines. All four tumor samples expressed both hBD-1 and hBD-2 mRNA, although the mRNA level of each protein varied. These results indicate that SCCs in which hBD expression is downregulated, may be susceptible to bacterial infection.

Influences of 4-meta/MMA-TBB adhesive resin on osteodentinogenesis of transplanted rabbit dental pulp in vivo: immunohistochemical and electronmicroscopic studies

The purpose of this study was to investigate the influence of 4-META/MMA-TBB adhesive resin (4-META resin) on osteodentinogenesis of transplanted pulp in vivo. Dental pulp was obtained from the incisors of adult rabbits. 4-META resin was applied to the pulp tissue, and the pulp tissue with 4-META resin was autotransplanted beneath the renal capsule with the pulp side touching the kidney. Pulp tissue alone was also transplanted as a control. The animals were sacrificed at 3, 7, and 14 days after the experiment, and the specimens were examined morphologically. At 3 days, proliferation of mesenchymal cells was observed, and alkaline phosphatase activity (ALP) and osteocalcin were detected throughout the entire transplanted pulp area. In the experimental case, a thin, highly electron dense zone and a granular layer were observed. Under this layer, only a cell-membrane-like structure, a cell with an unclear nucleus, a nucleus alone, and an organelle-like structure could be seen. Furthermore, an exudative layer with many neutrophils was observed, and apoptotic-body-like structures were also found in some areas. On days 7 and 14 in the control group, osteoblast-like cells had proliferated, and osteodentin formation was initiated throughout the entire transplanted pulp area. In the experimental cases at 7 and 14 days, the entire transplanted area had become osteodentin except for a thin fibrous layer under the 4-META resin. These results suggested that the components of 4-META resin such as MMA and 4-MET (A), which guide the polymerization, might cause degeneration of, but not disturb, the wound healing of the pulp tissue.

Clinical investigation of atypical adenomatous hyperplasia of the lung

The clinicopathologic characteristics of atypical adenomatous hyperplasia (AAH) remain unclear. A total of 137 patients underwent resection for adenocarcinoma of the lung at our institution. Examination of resected lung tissue showed that in addition to adenocarcinoma AAH was present in 26 cases and was not present in 111 cases. All nonsmokers with AAH (n = 13) had earlier-stage disease (stage IA, IB, IIA, and IIB) and no history of respiratory disease. Among patients with stage IA disease, the relapse-free and overall survival curves for those with AAH (n = 14) tended to be better than for those without AAH (n = 40), but the difference was not statistically significant (P = 0.056 and 0.087, respectively). Concurrent presence of AAH may be a favorable prognostic indicator in patients with stage IA adenocarcinoma.

Circadian variation of idiopathic ventricular tachycardia originating from right ventricular outflow tract

We determined circadian variation of isolated ventricular premature complexes (VPCs), 2 to 4 consecutive VPCs, and ventricular tachycardia (5 consecutive VPCs) originating from the right ventricular outflow tract in patients without apparent structural heart diseases. There was apparent circadian variation with 2 prominent peaks for these ventricular arrhythmias, and blockade abolished ventricular tachycardia and attenuated the circadian variation of consecutive VPCs.

Clinical investigation of bronchioloalveolar carcinoma: a retrospective analysis of 53 patients in a single institution

BACKGROUND

Bronchioloalveolar carcinoma (BAC) has been reported to have unique clinicopathological features.

PATIENTS AND METHODS

This retrospective study was performed using data base including 871 patients treated for primary lung cancer between 1981 and 1995.

RESULTS

The patients with BAC included a larger proportion of female (P = 0.029) and smoked less (P = 0.002) than those with non-BAC. There was no difference in survival between surgically resected patients with BAC and those with non-BAC. Clinical Stage IV patients with BAC had a better response to chemotherapy than did those with non-BAC. Survival in the former group was better than that in the latter on univariate analysis, but the significance of this difference was not confirmed multivariate analysis.

CONCLUSION

The patients with BAC included a larger proportion of females and smoked less than those with non-BAC. Treatment results for BAC was comparable to those for non-BAC.

Pleomorphic adenoma with nuclear palisading arrangement of modified myoepithelial cells: histopathologic and immunohistochemical study

Pleomorphic adenomas with a nuclear palisading arrangement of spindle-shaped modified myoepithelial cells (MMCs), suggesting the appearance of palisading leiomyoma or Antoni's A type of neurilemmoma, are quite rare, and its cytologic nature has been poorly understood. This paper reports histologic and immunohistochemical findings of palisading MMCs in two cases of pleomorphic adenoma. Histologically, foci of spindle-shaped MMCs with nuclei in a palisading arrangement were scattered in the myxoid areas. Near the large foci of spindle-shaped MMCs with nuclear palisading arrangements, tiny foci of spindle-shaped MMCs forming nuclear palisading or rosette-like arrangements were seen. Such nuclear palisading arrangements of MMCs were suggestive of differentiation or transformation of MMCs into cells that were more smooth muscle in nature, supported by occasional existence of palisading leiomyoma in the myometrium and gastrointestinal tract. However, immunohistochemical findings of palisading MMCs in pleomorphic adenoma were similar to those of non-palisading MMCs, and showed no evidence of smooth muscle differentiation; neither palisading nor non-palisading MMCs in pleomorphic adenoma expressed desmin, muscle specific actin (HHF-35), alpha smooth muscle actin, or myoglobin. The biologic significance and formative mechanism of nuclear palisading arrangement of MMCs in pleomorphic adenoma could not be determined in the present study. However, if the MMCs with nuclear palisading arrangements in pleomorphic adenoma, presented here, are aspirated for cytologic diagnosis or are included in a small biopsy specimen, the correct diagnosis of pleomorphic adenoma may be confused by a suspicion of myogenic or neurogenic tumor.

Allogeneic peripheral blood stem cell transplantation for the treatment of refractory follicular lymphoma

A 38-year-old male with follicular lymphoma at clinical stage IV failed to achieve complete remission (CR), and developed leukemic change. After the patient was further treated with intensive chemotherapy for acute lymphoblastic leukemia, lymphoma cells in the peripheral blood and bone marrow disappeared, but the bulky mass persisted. Then, the patient received allogeneic peripheral blood stem cell transplantation (allo-PBSCT) from his human lymphocyte antigen (HL A)-identical brother following high-dose cyclophosphamide and 12 Gy total body irradiation, and the patient achieved CR with the disappearance of Bcl-2 rearrangement. The patient is now alive in continuous CR for more than 19 months after allo-PBSCT.

Connexins in the developing salivary glands

Freeze-fracture and immunohistochemistry were used to elucidate the ultrastructure of gap junctions and the expression of connexins (gap junction structural proteins) Cx32 and Cx43 in the developing rat submandibular glands. Developing rat submandibular glands were examined from the 17th gestational day to the 14th day after birth. Gap junctions could be observed as clusters of particles 9-12 nm in diameter during the gestational days. The junctions were very small and consisted of about 20 particles in a relatively regular arrangement with a wide center-to-center spacing of 15-18 nm on the PF face. Fluorescence spots reacting positively to Cx43 were found between glandular cells from the 17th gestational day. Very few spots positive to Cx32 could be detected during gestation, their numbers increasing after birth. The possibility that Cx32 may have a role in the establishment of secretory regulation and that Cx43 is associated before birth with glandular growth and differentiation is discussed.

A study of the proliferative activity of the long junctional epithelium using argyrophilic nucleolar organizer region (AgNORs) staining

The proliferative activity of the long junctional epithelium (LJE) in rats was examined using stains for argyrophilic proteins of the nucleolar organizer region (AgNORs protein). The LJE was experimentally produced by insertion of a rubber piece between maxillary molars for 1 wk. After removal of the rubber, the length and AgNORs parameters of the LJE were measured and analyzed statistically. The LJE widely covered the apical side of the exposed root surface 4 wk after the removal. Its length was longest after 4 and 8 wk; it became shorter subsequently. The AgNORs were visible as black dots of various sizes and numbers on the sections. A high potential for proliferation was obvious in the LJE after 4 wk and was maintained until 12 wk after the removal. The AgNORs ratio on the connective tissue interface of the LJE was about twice of that of normal junctional epithelium after 4-12 wk. The proliferative activity on the root surface side was slightly increased after 4 wk. There was no significant difference in proliferative activity between the coronal and apical sides. These results suggest that the proliferative activity of the LJE is maintained continuously at a high level on the connective tissue interface supplying the epithelial cells. Basal cells proliferate at the connective tissue interface of the LJE, migrate directly to the root surface or via the apical portion and finally desquamate from the surface of the epithelium.

An immunoelectron microscopic localization of noncollagenous bone proteins (osteocalcin and osteopontin) at the bone-titanium interface of rat tibiae

This study was designed to investigate by postembedding immunogold method the localization and distribution of osteocalcin (Ocl) and osteopontin (Opn) at the bone-titanium interface in rat tibiae 14 and 28 days postimplantation to determine which bone proteins are present at this interface. Both proteins were widely distributed on the newly formed bone and accumulated predominantly in the region of bone close to the titanium, in electron-dense patches in the bone, and at the osteocytic lacunae. Collagenous osteoid showed little or no labeling for either Ocl or Opn. An amorphous zone (20-50 nm) was interposed between the titanium and interfacial slender cells, osteoid, or bone, and was labeled strongly for Ocl but only weakly for Opn. Furthermore, a second electron-dense layer, the lamina limitans, which faces the titanium, was labeled strongly for Opn but weakly for Ocl. Ocl as a marker protein of osteoblasts was sometimes found in the granules and vesicles of the interfacial cells and extracellularly in their intercellular spaces, close to the titanium. However, Opn was not detected in any granules. This is the first report to show that the amorphous zone contains large amounts of Ocl and small amounts of Opn, and that bone contacts titanium through this Ocl-rich amorphous zone. Furthermore, it is suggested that the interfacial cells seem to be osteoblasts, and that Ocl in the amorphous zone is produced and secreted by these cells and functions with Opn as a regulator of the mineralization front close to the titanium, and as a mediator of cell-matrix and matrix-matrix/mineral adhesion along the titanium.

Basaloid-squamous cell carcinoma of the oral mucosa: report of two cases and study of the proliferative activity

Two cases of basaloid-squamous cell carcinoma (BSC) of the oral mucosa are described. The first case occurred at the floor of the mouth in a 58-year-old man, and the second case occurred at the mandibular gingiva in a 79-year-old woman. The laboratory data of the first case showed a positive response to hepatitis C virus antibody. In the first case, the tumor mass measured 4 x 4 cm in size, and was located at the lingual side of the median mandible beside the sublingual gland. In the second case, the tumor mass measured 25 x 15 mm in size, and was located in the alveolar mucosa of the right mandible. Histologically, both tumors showed a neoplastic epithelium arranged in a solid pattern with evidence of peripheral palisading, central necrosis, and some squamous differentiation. The proliferative activities of the BSC were compared with conventional squamous cell carcinomas (SCC) in the oral floor and gingiva, respectively, by employing a sensitive argyrophilic nuclear organizer region (AgNOR) staining method. The number of AgNOR per nucleus of the BSC was higher than that of any other SCC cases. The results support the opinion that BSC of the oral mucosa has a worse prognosis than conventional SCC.

An immunocytochemical study for lysosomal cathepsins B and D related to the intracellular degradation of titanium at the bone-titanium interface

The morphological relationship between titanium and lysosomal proteinases, cathepsins B and D, at the bone-titanium interface using titanium-coated plastic implants placed for 28 days in the tibiae of 6-week-old rats was immunocytochemically investigated by the colloidal immunogold-silver method. Under light microscopy the titanium layer appeared to make direct contact with the bone and one or a few layers of slender cells were interposed between the bone and titanium. Ultrastructurally, the titanium came in contact with the bone or the slender cell layer through a 20 to 40 nm thin amorphous zone. The slender cells at the bone-titanium interface consisted of two types; one was an osteoblast type with glycogen granules which was found along the newly-formed bone facing titanium layer. The other was a fibroblast type which came in contact with the titanium layer and occasionally endocytosed the detached titanium fragments. In addition, some of the slender cells also showed degenerative changes. Immunocytochemically, cathepsins B and/or D were sometimes colocalized in some phagolysosomes with titanium fragments. These findings suggested that the fibroblast types at the bone-titanium interface may act as scavengers to remove both cell debris and titanium by means of some endocytotic ability, and lysosomal cathepsins also developed in response to the endocytosed titanium. The osteoblast type also appears to show a high degree of osteogenic activity around the titanium-coated plastic implants.

[A 10-year-old case with idiopathic oculomotor nerve palsy]

We reported a 10-year-old girl with acquired left oculomotor nerve palsy. Neurologic and radiological examinations failed to reveal the etiology. Following administration of corticosteroid and vitamin B6, diplopia improved within 6 weeks, and mydriasis has been improving over the past 9 months. Idiopathic acquired oculomotor nerve palsy is a very rare condition in childhood, and prognosis of the disease is sometimes good.

Role of sympathovagal balance in the initiation of idiopathic ventricular tachycardia originating from right ventricular outflow tract

VT originating from the right ventricular outflow tract (RVOT) is prone to occur when sympathetic nervous activity is increased. beta-Blockade is, therefore, effective in suppressing this VT. The purpose of this study was to determine the role of sympathovagal balance assessed by heart rate variability (HRV) in the spontaneous initiation of repetitive premature ventricular contractions (PVCs) and VT (five or more consecutive PVCs) arising from RVOT in seven patients without structural heart diseases. Frequency-domain measures of HRV were determined by analyzing 24-hour Holter electrocardiographic recording with the maximum entropy method over a 1,280-second period immediately before the onset of 35 single PVCs, 26 episodes of 2-4 consecutive PVCs, and 21 episodes of VT. High frequency component (HF: 0.15-0.40 Hz) was used as an index of parasympathetic activity, and the ratio of low frequency component (LF: 0.04-0.15 Hz) to HF (LF/HF ratio), as an index of sympathovagal balance. NN50(%), a time-domain variable of parasympathetic activity, was also determined. Mean RR interval and any measures of HRV did not change significantly before single PVCs. Mean RR interval shortened and HF decreased prior to repetitive PVCs and VT. The LF/HF ratio, however, increased only before the onset of VT. NN50(%) tended to decrease before repetitive PVCs and decreased significantly before VT. With propranolol (30-60 mg/day), frequency of repetitive PVCs was suppressed from 2,048 +/- 1,201 to 746 +/- 658/day and VT was totally abolished, but frequency of single PVCs did not change significantly. In conclusion, sympathetic predominance plays an important role in the initiation of repetitive PVCs and VT originating from RVOT in patients without structural heart diseases.

Single-trial analysis of P3 in patients with generalized epilepsy

The latencies and amplitudes of averaged P3, and the latencies, amplitudes and frequency components of single EEG responses to target tones were analyzed in 9 control subjects (CS group), 6 epileptics whose mean IQ was 100 (EP group) and 6 epileptics whose mean IQ was 52 (RE group), using an auditory oddball task. All of the subjects responded to the target tones correctly and there were no differences in the incidence of error in response to the target tones, or in the latencies and amplitudes of the averaged P3 among the three groups. However, the reaction times (RTs) in the RE group were significantly longer than those in the other groups (P < 0.05). Single EEG responses to target tone (single-trial ERPs) were classified into 2 types, those with and those without the P3 component. Type 1 had the P3 component and was observed in 42% of all of the responses in the RE group, significantly less than those in the CS (64%) and EP (61%) groups. The peak latencies of P3 in type 1 were similar among the three groups, but the amplitudes of P3 in type 1 in the RE group were significantly greater than those in the CS and EP groups. RTs in the RE group were significantly longer than those in the other groups, and had no correlation with the P3 latencies of type 1. There was little difference in the results of the frequency analysis among the three groups. These results suggest that all subjects in three groups recognized the target tones correctly, but they did not evaluate every target tone, since the incidence of P3 was almost 60% in the CS and EP groups, and 40% in the RE group. The characteristics of cognition and evaluation in three groups were the same, but the decrease in incidence of evaluation and the dissociation between the cognition and the response execution might be caused by impairment of the subject-environment contact mechanism, which resulted in the decrement of IQ in the RE group.

Immunolocalization of proliferating cell nuclear antigen in the peri-implant epithelium

The aim of the present study was to investigate the proliferating activity of peri-implant epithelium immunohistochemically using proliferating cell nuclear antigen (PCNA). Eight ITI (Internationale Team für Implantologie) implants were placed into simulated sockets in the mandibles of two beagle dogs two months following tooth extraction. As a control, junctional epithelium of the molar teeth in the same animals were used. The nature of staining and the distribution of PCNA immunoreactivity were determined by scoring a minimum of 100 cells on two sections from each of the implants. In the junctional epithelium, the immunoreactivity to PCNA was detected mainly in the basal cells, in some of the prickle cells, and in a few cells attached to the enamel. In peri-implant epithelium, only some of the basal cells were positive for PCNA. The PCNA score of the peri-implant epithelium was significantly lower than that of junctional epithelium. These results suggest that the peri-implant epithelium maintains a lower capacity to act as a proliferative defence mechanism than does the junctional epithelium.

Cell death during tooth eruption in the rat: surrounding tissues of the crown

We investigated the occurrence of apoptosis and other types of cell death around the crown during tooth eruption of the rat upper molar. The TdT-mediated-dUTP-biotin nick end labeling (TUNEL) method and transmission electron microscopy (TEM) were employed. Apoptosis was detected by both TUNEL and TEM in part of the reduced enamel epithelium and connective tissue in the resorbing bony crypt of the pre-erupted tooth. In TEM, a large number of cells showed condensed chromatin and membrane-bound small bodies (apoptotic bodies). Macrophages that phagocytosed apoptotic bodies could be detected. Based upon the distance between bone surface and these apoptotic cells, and the characteristics of their organelles, we suggested that the apoptotic cells might be osteocytes, bone-lining cells (osteoblasts), and macrophages. We surmised that the osteoclasts had also died. Cells which contained autophagic vacuoles and autophagosomes, and others whose cytoplasm had dissolved, were also frequently observed. No progressive cell death was found in the oral epithelium or the fibrous connective tissue over the crown. These results suggest that apoptosis gives rise to some cell death during tooth eruption, but that other types of cell death also occur in various cells.

Merkel cell carcinoma of palatal mucosa in a young adult: immunohistochemical and ultrastructural features

The first case report of a merkel cell carcinoma arising from the palatal mucosa in a young adult is presented. The histopathological similarities of this tumour in skin and oral mucosa are also discussed. The patient was a 14-year-old female with a non-symptomatic painful swelling in the left molar region of the maxilla. Under the diagnosis of a malignant tumour, a partial maxillary resection was performed, but there was a recurrence, and finally the patient died of cerebral metastasis. The tumor was composed mainly of uniform small cells. Immunohistologically, a large number of the cells were reactive to neuron specific enolase (NSE) and cytokeratin CK19, and some of the cells were positive to CK8, CK13, CK20, PGP9.5 and CEA focally and slightly. Pseudo-rosette formation and squamous differentiation were frequently detected. The ultrastructure of the tumour cells showed abundant Golgi bodies associated with neurosecretory granules. We conclude that it is the first case of a Merkel cell tumour arising from palatal mucosa and invading underlying bone with reactive hyperplasia. These findings closely resemble those of the same tumour occurring in the skin

Adenomatoid odontogenic tumor with extensive formation of tubular dentin

Although the adenomatoid odontogenic tumor (AOT) is categorized as an odontogenic epithelial tumor with odontogenic ectomesenchyme, AOT with induction of true tubular dentin with or without concomitant formation of enamel is exceedingly rare. This paper reports a case of AOT showing evidence of extensive induction of tubular dentin, but without concomitant formation of enamel. The patient was a 20-year-old female with a rather well-circumscribed intraosseous lesion of the maxillary incisor-premolar area without an embedded tooth. Histologically, extensive induction of a dysplastic form of tubular dentin with globular calcification was evident, in addition to the characteristic histological features of AOT. The present case lends support to the categorization of AOT as an odontogenic tumor consisting of a disorderly mixture of odontogenic epithelium and odontogenic ectomesenchyme with or without dental hard tissue formation.

Clear cell odontogenic carcinoma in the mandible: histochemical and immunohistochemical observations with a review of the literature

A rare case of clear cell odontogenic carcinoma was investigated using histochemical and immunohistochemical methods. The tumor occurred in the anterior mandible of a 69-year-old Japanese man. Histologically, the tumor was composed mostly of large clear cells and squamous cells. Columnar-shaped cells with basophilic nuclei polarized away from the basement membrane were observed at the periphery of the tumor foci. The tumor cells had aggressively invaded muscle and perineural tissues. The tumor cells were positive for PAS staining. Immunohistochemically, tumor cells reacted positively to keratin, cytokeratin19, epithelial membrane antigen, and S-100 protein. The tumor was diagnosed as a clear cell odontogenic carcinoma. Its characteristics are discussed in term of its histopathological, histochemical and immunohistochemical features.