Reconstruction of segmental mandibular defects by distraction osteogenesis for mandibular reconstruction

BACKGROUND: Distraction osteogenesis is an established technique for the lengthening of long bones and correction of selected craniofacial deformities. Regenerate osteoid bone matrix formed during the distraction phase is malleable and can recreate the three-dimensional form of native bones. Animal experiments and early clinical experience have confirmed that distraction osteogenesis can be used for the reconstruction of segmental bony defects. Herein we discuss the principles of distraction osteogenesis in reference to reconstruction of segmental bony defects and report its clinical application of the mandible continuity defects. PATIENTS AND METHODS: Four patients (age, 7-83 years) with critical segmental mandibular defects (range, 3.5 cm-6.5 cm), resulting from ablative oncologic head and neck surgery underwent primary mandibular reconstruction by transport distraction osteogenesis. Two defects were at the angle and body region, one at the body, and the other at the parasymphysis and body region. Synthes Titanium Multi-vector and Leibinger Multi-guide distractors in bifocal (n = 2) and trifocal (n = 2) architecture were used after the stabilization of the segmental continuity defect using a defect-bridging mandibular reconstruction plate. Osteodistraction was carried out at a rate of 1 mm per day, with once or twice a day rhythm, after a 1-week latency period. The consolidation period was equal to the period of distraction. RESULTS: All patients tolerated the distraction procedure. Satisfactory bone formation was observed in two patients, and partial bone formation was seen in one patient. Treatment failure was encountered in one patient who had a second oral cavity primary tumor observed during the consolidation period, requiring interruption of the treatment sequence. CONCLUSIONS: Mandibular reconstruction with distraction osteogenesis is a potentially useful technique in selected patients with segmental mandibular continuity defects after ablative head and neck cancer surgery.     

Oropharyngeal kaposi sarcoma in related persons negative for human immunodeficiency virus

OBJECTIVES: Kaposi sarcoma (KS) is a vascular tumor that can affect the mucosa of the upper aerodigestive tract. Although KS is the most common malignancy in patients with acquired immunodeficiency syndrome, it is rare in immunocompetent persons. We describe an unusual presentation of KS in 2 related individuals and describe our attempts to determine whether oropharyngeal KS is associated with human herpesvirus 8 (HHV-8). METHODS: All relevant clinical and surgical information, including information on tumor histopathologic and human immunodeficiency virus (HIV) serologic tests, was abstracted from the patient charts and electronic databases. HHV-8 immunohistochemistry was performed on paraffin-fixed specimens. RESULTS: Both patient 1 and patient 2 (the nephew of patient 1) were referred for workup of a tonsillar mass that was pathologically confirmed to be KS. In each case, HIV serologic testing was negative, and a screening immunologic workup, including a quantitative natural killer cell count, a B- and T-lymphocyte count, and immunoglobulin analysis, also yielded findings that were within normal limits. Immunohistochemistry performed on 1 pathological specimen showed positive staining for the presence of HHV-8, the etiologic agent of KS. CONCLUSIONS: The presence of oropharyngeal KS in 2 related HIV-negative individuals supports a role for genetic factors in susceptibility to KS, a common exposure to an infectious agent such as HHV-8, or both. Whereas most KS cases in industrialized countries are associated with immunodeficiency, clinical and laboratory data do not suggest that either of the patients described in this report are immunodeficient. Their susceptibility to KS may be secondary to a subtle inherited defect in host resistance to HHV-8, or another unknown factor.     

Malignant solitary fibrous tumor of the tongue

Solitary fibrous tumor is a generally benign spindle-cell neoplasm that has been predominantly described in the visceral pleura and other serosal sites and is extremely rare in the head and neck area. We report the first known case of malignant solitary fibrous tumor of the tongue in a 57-year-old female patient who experienced rapid growth of a longstanding right anterior tongue mass, with associated dysphagia and dysarthria. Magnetic resonance imaging was suggestive of a low-flow vascular malformation not requiring preoperative embolization. The patient underwent partial peroral glossectomy for the excision of the tumor. Final pathology, however, was consistent with solitary fibrous tumor, characterized as malignant by histopathologic criteria, and the patient was returned for re-excision of the close surgical margins. The patient has experienced symptomatic improvement, and she remains free of recurrence 12 months later. All reports of solitary fibrous tumors of the oral cavity and 3 reports of the tongue tumors described in the literature to date represent benign lesions. To our knowledge, this is the first report of a malignant solitary fibrous tumor of the tongue. Presentation, differential diagnosis, criteria for malignancy, treatment, and possible prognostic implications of this rare entity are discussed.     

Ly6G ligation blocks recruitment of neutrophils via a β2-integrin-dependent mechanism

Ly6G is a glycosylphosphatidylinositol (GPI)-anchored protein of unknown function that is commonly targeted to induce experimental neutrophil depletion in mice. In the present study, we found that doses of anti-Ly6G Abs too low to produce sustained neutropenia remained capable of inhibiting experimental arthritis, leaving joint tissues free of infiltrating neutrophils. Thioglycollate-stimulated peritonitis was also attenuated. No alteration in neutrophil apoptosis was observed, implicating impaired recruitment. Indeed, Ly6G ligation abrogated neutrophil migration toward LTB(4) and other chemoattractants in a transwell system. Exploring the basis for this blockade, we identified colocalization of Ly6G and β2-integrins by confocal microscopy and confirmed close association by both coimmunoprecipitation and fluorescence lifetime imaging microscopy. Anti-Ly6G Ab impaired surface expression of β2-integrins in LTB(4)-stimulated neutrophils and mimicked CD11a blockade in inhibiting both ICAM-1 binding and firm adhesion to activated endothelium under flow conditions. Correspondingly, migration of β2-integrin-deficient neutrophils was no longer inhibited by anti-Ly6G. These results demonstrate that experimental targeting of Ly6G has functional effects on the neutrophil population and identify a previously unappreciated role for Ly6G as a modulator of neutrophil migration to sites of inflammation via a β2-integrin-dependent mechanism.