Immunohistochemical and histochemical characterization of intraosseous arteriovenous malformations of the jaws: analysis of 16 cases with emphasis on GLUT-1 immunophenotype

Effect of vasoconstriction by dexmedetomidine in the mandible of rat

Background

In recent years, dexmedetomidine (DEX) has been proposed as a useful vasoconstrictor for local anesthesia because it is less effective in circulation than clonidine of antihypertensive drugs. In addition, DEX is expected to act as a vasoconstrictor during local anesthesia. However, histomorphometric studies demonstrating that DEX exerts vasoconstrictive effects are lacking. This study aimed to clarify whether DEX exerts a histomorphologically vasoconstrictive effect on blood vessels in the mandible of rats.

Methods

A total of 12 male Wistar rats were used. General anesthesia was induced and maintained using sevoflurane. Normal saline (0.2 ml) was injected on the left side of the jaw (DEX (-) effect site) and 0.2 ml normal saline containing 12.5 µg/ml DEX was injected on the right side of the jaw (DEX (+) effect site). The puncture point was located on the mesial side of the first molar, 1 mm away from the gingival sulcus. Following decalcification, the specimens were paraffinized and sagittally sliced into 20 µm-thick sections, followed by staining with anti-α smooth muscle actin antibody. The intravascular lumen area was measured in the oral mucosa, periodontal ligament, mandibular bone above the root apex, mandibular bone below the root apex, and dental pulp. The unpaired t-test was used for statistical analysis, and a P value < 0.05 was considered statistically significant.

Results

Compared to the DEX (-) effect site, the intravascular lumen area in the oral mucosa and periodontal ligament of the DEX (+) effect site was significantly decreased. No significant difference was observed in the intravascular lumen area between the DEX (-) and DEX (-) effect sites in the mandibular bone above and below the root apex and dental pulp.

Conclusion

A direct vasoconstrictive effect of DEX was not observed in the intravascular lumen of the mandibular bone above and below the root apex and dental pulp; however, it was observed in the oral mucosa and periodontal ligament.

On Vascular Lesions of the Thyroid Gland with Emphasis on Intrathyroidal Hemangioma: Clinicopathologic Characterization of Two Cases and Review of the Literature

Mesenchymal neoplasms of the thyroid gland are exceptionally rare accounting for less than 0.5% of all intrathyroidal tumors with hemangiomas comprising merely 6% of them. The clinicopathologic characteristics of two additional examples of thyroid hemangioma together with a thorough review of the pertinent literature are presented. A 62-year-old man and an 18-year-old woman presented with asymptomatic, soft-to-palpation, mobile nodules of the right thyroid lobe classified as TI-RADS 5 and TI-RADS 4, respectively, on ultrasound imaging. Microscopically, lesions featured a circumscribed, unencapsulated, lobular proliferation of variably-sized, congested, vascular channels lined by a single layer of flattened, cytologically bland endothelial cells, together with interspersed residual follicles. Vascular endothelial cells were strongly positive for CD31, CD34 and ERG, and negative for pancytokeratin AE1/AE3, TTF1, and PAX8. A diagnosis of cavernous hemangioma was rendered in the clinical setting of Hashimoto thyroiditis and follicular adenoma, respectively. Following inclusion of the current cases, a total of 53 intrathyroidal hemangiomas were identified in the literature with a patient mean age of 48.9 years (range = 0.17-84) and a slight female predilection (F:M = 1.4:1). A proclivity for the right thyroid lobe (59.6%) was noted with the striking majority of cases exhibiting features of cavernous hemangioma (95.2%). Prognosis is favorable and surgical resection is considered curative. The occasionally alarming clinical presentation in conjunction with absence of pathognomonic imaging features and limited diagnostic accuracy of FNA cytopathology for such lesions renders surgical intervention necessary for definitive diagnosis of intrathyroidal hemangiomas and exclusion of other epithelial and non-epithelial pathologic entities.

A Histological Study of Vasoconstriction by Local Anesthetics in Mandible

To assess the effect of epinephrine-containing local anesthetics on vasoconstriction, we immunohistochemically measured the intravascular lumen area in different regions of the mandible. Twelve male Wistar rats were used. General anesthesia was induced and maintained with sevoflurane. Infiltration anesthesia was performed with 0.2 mL of epinephrine-free 2% lidocaine (E-) near the left mandibular first molar and with 0.2 mL of epinephrine-containing 2% lidocaine (E+) near the right mandibular first molar. After decalcification, the specimens were paraffinized, and thin sections were prepared and immunohistologically stained with an antismooth muscle actin antibody. The intravascular lumen area was measured in the mucosa, periodontal membrane, Haversian/Volkmann's canal, and bone marrow. A Mann-Whitney U test was used for statistical processing, and p < .05 was considered to indicate a statistically significant difference. In the oral mucosa and the periodontal membrane, E+ had a significantly smaller vascular lumen area than E-. In the Haversian/Volkmann's canal and the bone marrow, no significant intergroup difference was observed in the intravascular lumen area. We postulate that this is due to a low smooth muscle content of blood vessels in the mandible and suggest that the vasoconstrictive effect of epinephrine-containing local anesthetics within the mandible is ineffective.