Constantinos Alexandridis

Parapharyngeal space tumors: surgical approaches in a series of 13 cases

Tumors originating in the parapharyngeal space are rare; they comprise approximately 0.5% of head and neck tumors. Most (70-80%) are benign and the most frequent origins are salivary and neurogenic. The aim of this study is to present the surgical procedures used for the treatment of 13 patients with parapharyngeal space tumors; 11 of them were suffering from benign tumors (the most frequent being pleomorphic adenoma; 8 cases) and 2 from malignant lesions. The following surgical approaches were used: intraoral (2 cases), transcervical (4 cases) and transmandibular (7 cases) with different types of mandible osteotomies. The type of surgical approach was dictated by the type of the lesion (malignant or benign), the exact location, the size, the vascularity and the relation of the tumor to the neck neurovascular bundle. In all cases the selected surgical approach allowed the complete resection of the tumor, obtaining clear margins in cases of malignancy, without adding to the patients preoperative morbidity. It was concluded that the surgical approach to the parapharyngeal space tumors must be adjusted to the tumor characteristics and be as wide is necessary to achieve its complete removal with safety.

Bone Regeneration Using B-Tricalcium Phosphate in a Calcium Sulfate Matrix

The aim of the study was the histomorphometric comparison of the osteogenic potential of beta-tricalcium phosphate (beta-TCP) alone or in a calcium sulfate matrix. Three round defects, 10 mm (diameter) x 5 mm (depth), were created on each iliac crest of 4 dogs. The defects were divided into 3 groups. Ten defects were filled with beta-TCP in a calcium sulfate (CS) matrix (Fortoss Vital; group A), 10 defects were filled with beta-TCP alone (Fortoss Resorb; group B), and 4 defects were left ungrafted to heal spontaneously (group C). All defects were left to heal for 4 months without the use of a barrier membrane. Histologic evaluation and morphometric analysis of undecalcified slides was performed using the areas of regenerated bone and graft remnants. All sites exhibited uneventful healing. In group A sites (beta-TCP/CS), complete bone formation was observed in all specimens, graft granules dominated the area, and a thin bridge of cortical bone was covering the defect. Group B (beta-TCP) defects were partially filled with new bone, the graft particles still dominated the area, while the outer cortex was not restored. In the ungrafted sites (group C), incomplete new bone formation was observed. The outer dense cortical layer was restored in a lower level, near the base of the defect. The statistical analysis revealed that the mean percentage of new bone regeneration in group A was higher than in group B (49.38% and 40.31%, respectively). A statistically significant difference existed between the 2 groups. The beta-TCP/CS group exhibited significantly higher new bone regeneration according to a marginal probability value (P = .004 < .05). The use of beta-TCP in a CS matrix produced significantly more vital new bone fill and preserved bone dimensions compared with the use of beta-TCP alone.

Parathyroid hormone-related peptide (PTHrP), parathyroid hormone/parathyroid hormone-related peptide receptor 1 (PTHR1), and MSX1 protein are expressed in central and peripheral giant cell granulomas of the jaws

OBJECTIVE Parathyroid hormone-related peptide (PTHrP) binds to the parathyroid hormone receptor type 1 (PTHR1), which results in the activation of pathways in osteoblasts that promote osteoclastogenesis through the RANK/RANKL system. RANK/RANKL expression has been shown in central giant cell granuloma of the jaws but PTHrP/PTHR1 has not. MSX1 protein is a classical transcription regulator which promotes cell proliferation and inhibits cell differentiation by inhibiting master genes in tissues such as bone and muscle. It has been implicated in the pathogenesis of cherubism, and its expression has been reported in a single central giant cell granuloma (CGCG) case. We aimed, therefore, to study the expression of those proteins by the different cellular populations of central and peripheral giant cell granulomas (PGCGs) of the jaws. STUDY DESIGN Twenty cases of CGCG and 20 cases of PGCG of the jaws were retrospectively examined by immunohistochemistry for the percentage of positively staining cells to antibodies for PTHrP, PTHR1, and MSX1, using a semiquantitative method. RESULTS In both CGCG and PGCG of the jaws, PTHrP and PTHR1 were abundantly expressed by type I multinucleated giant cells (MGC) and mononucleated stromal cells (MSC) with vesicular nuclei, whereas type II MGC and MSC with pyknotic nuclei expressed those proteins to a lesser extent. In both CGCG and PGCG of the jaws, MSX1 was abundantly expressed by type I MGC and MSC but type II MGC did not express it. A statistically significant difference (P < .05) was observed between CGCG and PGCG in the expression of PTHrP in type II MGC and MSC with pyknotic nuclei and in the expression of PTHR1 in type II MGC. CONCLUSIONS We suggest that in CGCG and PGCG of the jaws, PTHrP-positive immature osteoblasts activate PTHR1-positive mature osteoblasts to produce RANKL which interacts with RANK on the PTHrP/PTHR1-positive osteoclast-precursor cells found in abundance in the stroma of giant cell lesions and induces osteoclastogenesis through the classic pathway. Cells of the jawbones, the periodontal ligament, or the dental follicle, originating from the neural crest, may be involved in the pathogenesis of giant cell lesions of the jaws. Further study is required for these suggestions to be proved.

Comparative biomechanical evaluation of mono-cortical osteosynthesis systems for condylar fractures using photoelastic stress analysis

Fractures of the condyle account for 20-30% of all mandibular fractures, and are therefore one of the most common facial injuries. Precise evaluation of the mechanical stresses that develop in a fractured mandible is essential, particularly for the testing of systems currently used for stabilisation of the condylar fragment. Photoelastic stress analysis can be used to visualise alterations in the strain that is induced in the mandible by a fracture, and in the osteosynthesis materials used to stabilise it. This method, used on currently used osteosynthesis materials, showed that stabilisation of a subcondylar fracture with a single miniplate does not provide enough stability, whereas the use of two miniplates - properly positioned - offers sufficient stability in all loading conditions. A microplate may be used as a tension-resisting plate with equally good results.

Surgical management of a large median dermoid cyst of the neck causing airway obstruction. A case report

IntroductionDermoid cysts of the floor of the mouth and submandibular space represent an unusual clinical entity.Case reportA case of an enlarged median dermoid cyst in a young female adult causing obstruction of the airway is reported.DiscussionThe need of an extraoral and intraoral incision for the removal of the cyst is discussed, along with a review of the literature.

Use of a porcine dermal collagen graft (Permacol) in parotid surgery

Our aim was to present the results of the use of porcine dermal collagen graft (Permacol) in the prevention of Freys syndrome and face-contouring aesthetic deformities after operations on the parotid. We treated 19 patients with parotid tumours. After resection, a Permacol sheet was applied to the perimeter of the tissue deficit so that it was fully covered, and was sutured firmly. This technique produced satisfactory aesthetic results with good facial contouring in all patients. It also protected the exposed parotid nerve plexus, and none of the patients developed Freys syndrome. Permacol produced good results in both postoperative facial contouring and prevention of Freys syndrome.

Vascular fractal dimension and total vascular area in the study of oral cancer.

Microvessel quantification has been studied extensively as a factor reflecting angiogenesis in various malignant tumors. The aim of our study was to evaluate the vascular fractal dimension and the immunohistochemically positive total vascular area in oral cavity carcinomas in order to assess their potential value as factors reflecting angiogenesis.

Absence of hotspot mutations in exons 9 and 20 of the PIK3CA gene in human oral squamous cell carcinoma in the Greek population.

OBJECTIVE Phosphatidylinositol-3 kinases (PI3K) are a group of heterodimeric lipid kinases that regulate many cellular processes. Recent studies have reported high frequencies of somatic hotspot mutations in the phosphatidylinositol-3 kinase catalytic alpha (PIK3CA) gene, which encodes for one of these kinases, in several human solid tumors, including oral squamous cell carcinoma (OSCC). The aim of this study was to determine the frequency of hotspot mutations in exons 9 and 20 of the PIK3CA gene in OSCC in the Greek population. STUDY DESIGN Eighty-six formalin-fixed and paraffin-embedded primary tumor specimens were analyzed by direct genomic DNA sequencing. Chi-square was used for statistical analysis. RESULTS No hotspot mutations were detected in any of the samples. Two intronic polymorphisms IVS8 and IVS9 were detected, mainly in patients with cancer of the buccal mucosa and lower gingival and alveolus respectively. CONCLUSIONS PIK3CA hotspot mutations are unlikely to play a major role in the pathogenesis of OSCC in the Greek population.

Intraosseous mandibular venous malformation.

Intraosseous venous malformations are rare benign lesions that account for approximately 0.5% to 1% of all osseous tumors. Involvement of the facial skeleton is rather uncommon, with the mandible and maxilla most frequently involved. In the current study, we report a case of an intraosseous venous malformation in a 52-year-old male patient with a history of mandibular keratocystic odontogenic tumor. The patient presented with an asymptomatic bony lesion in the mandible. Treatment involved surgical excision. Histopathologic examination of the excised specimen revealed an intraosseous venous malformation. Twelve months postoperatively, there was no evidence of recurrence.

Metastases to Supramandibular Facial Lymph Nodes in Patients With Squamous Cell Carcinoma of the Oral Cavity

PURPOSE This study evaluated the frequency of metastases to supramandibular facial lymph nodes (SFLNs) in patients with squamous cell carcinoma (SCC) of the oral cavity. PATIENTS AND METHODS SFLNs were identified and removed during neck dissection from 43 patients with oral SCC. All of them were histopathologically and immunohistochemically examined, to detect possible metastases and micrometastases. RESULTS Metastases to SFLNs were present in 6 patients (13.95%). Metastases were much more common among patients with palpable neck nodes, larger size of the primary site, advanced TNM stage, and greater age and those in whom the primary site was located in the mucosa of the alveolar ridge of the mandible. CONCLUSIONS Surgical procedures in the region of the SFLNs must be performed very carefully, because of their close relation with the marginal mandibular nerve. In patients with oral SCC and palpable neck nodes, those with advanced disease, and those in whom the primary site is located in the mucosa of the alveolar ridge of the mandible, removal of SFLNs must be considered.