The head and neck is the most frequent location for extraneuraxial meningiomas, be they wholly extracranial or extraspinal or extensions of central nervous system meningiomas. Regardless of anatomic site of origin, nearly all meningiomas arise from meningocytes of arachnoid granulations. Ectopic arachnoid cell clusters have a predilection for areas of dural penetration of cranial nerves, and it is in these areas that most extracranial meningiomas are found. Surgical excision is the mainstay of treatment and must be planned by radiologic studies to determine the extent of the tumor and the presence or absence of a companion central nervous system meningioma. The often locally invasive and aggressive behavior of the meningiomas belies their benign histologic appearance.
The skin and subcutaneous tissue and mucosae of the head and neck are areas of predilection for granular cell tumors. These often histogenetically enigmatic lesions have two principal clinicopathologic presentations: an infantile (congenital) epulis form of the gnathic gingiva and a noncongenital soft tissue and aerodigestive form. Recurrences of either form are largely attributable to marginal excision and, for all sites, approach 15%. A malignant granular cell tumor is recognized, but requires rigorous histologic confirmation.
We have observed inaccurate urine arsenic values with the method of isobaric fractionation, which was designed to correct for the 40Ar35Cl interference with 75As quantitation by inductively coupled plasma mass spectrometry. Isobaric fractionation, which is based on ion intensities at m/z 77 and 82, consistently underestimates the 40Ar35Cl interference and overestimates urine arsenic. We present an improved method for identifying the argon-chloride interference. We observed that signal intensities for the species 16O35Cl and 40Ar35Cl are proportional (I75 = 0.0295 x I51 - 14.7, r2 = 0.998; where Ix is the normalized ion intensity at m/z X) in water and urine, over a broad range of chloride concentrations (0-800 mmol/L). The proportionality constant is remarkably stable within a run (mean and SD, 0.0295 +/- 0.0023, based on 10 replicates of five chloride calibrators, 0, 100, 200, 400, and 800 mmol/L). Increased sensitivity (50-fold) for detecting the 40Ar35Cl interference provides improved accuracy for urine arsenic quantitation as demonstrated by a split-sample comparison with graphite-furnace atomic absorption spectrophotometry.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.