Ocular-adnexal lymphoid tumors: a clinicopathologic and molecular genetic study of 77 patients.

PURPOSE: To determine whether molecular genetic analysis of ocular-adnexal lymphoid tumors, combined with histopathology and tumor location, is helpful in predicting which patients will develop systemic lymphoma. METHODS: A combined retrospective and prospective study of 77 patients with ocular-adnexal lymphoid tumors was performed. The tumors were subdivided into conjunctival, orbital, and eyelid lesions, and all were studied using both routine histopathology and molecular genetic analysis. RESULTS: Most lesions (70%) were small cell lymphomas of the mucosa-associated lymphoid tissue type, and the majority of tumors (90%) contained monoclonal or oligoclonal populations of lymphocytes discovered on molecular genetic analysis. Additionally, 72% of tumors exhibiting clonality had more than one gene rearrangement. Fifty-three percent of patients developed extraocular lymphoma sometime during the course of their disease. Patients with gene rearrangements on Southern blot hybridization had a 52% incidence of nonocular disease, compared with 63% of those without rearrangements. Patients with conjunctival tumors had a 37.5% incidence of nonocular disease, those with orbital tumors had a 54% incidence, and those with eyelid tumors had a 100% incidence of nonocular lymphoma. Only two patients died as result of systemic lymphoma. CONCLUSIONS: Most ocular-adnexal lymphoid tumors are lymphomas of the mucosa-associated lymphoid tissue type. The majority of tumors exhibit gene rearrangements on molecular genetic analysis, and this technique was not helpful in predicting which patients would develop nonocular lymphoma. Tumor location did have predictive value: Conjunctival lesions had the lowest incidence of nonocular lymphoma, and lid lesions had the highest incidence. Even with disseminated disease, most patients have a favorable prognosis with treatment.     

Evaluation of Tc-99m-DTPA for renal clearance studies in the pig

Summary Conventional creatinine clearance studies in the pig are complicated by difficulties with catheterisation, infection, accurate collection and active creatinine renal tubular reabsorption. We compared a single injection, ^99mTc-DTPA elimination method with creatinine clearance. Nineteen pairs of GFR estimations were performed in 10 pigs: 7 in normal pigs and 12 following bile duct ligation and/or nephrectomy. Red cell and plasma protein binding of the isotope and its hepatobiliary excretion was assessed. Absolute and weight normalised endogenous creatinine clearances correlated significantly with ^99mTc-DTPA elimination. ^99mTc-DTPA red cell binding and hepatobiliary excretion were negligible. Thus, ^99mTc-DTPA elimination is a valid indicator of changes in renal function in grouped porcine studies, particularly in the biliary obstruction model. However, isotope plasma protein binding was high in the 2 normal pigs assessed. Individual accuracy would be improved by routine protein binding correction, unless consistently low for a particular preparation.     

The need for caution with topical anesthesia during endoscopic procedures, as liberal use may result in methemoglobinemia

During upper gastrointestinal endoscopy, topical oropharyngeal anesthesia with lidocaine and/or benzocaine is used routinely by many endodscopists. Although such a practice is usually safe, there have been a number of reports of methemoglobinemia induced by topical anesthesia. Early treatment is extremely important as the development of methemoglobinemia is potentially fatal. Methemoglobinemia should be considered when oxygen desaturation occurs without another explanation. In this case series, we report 4 cases of methemoglobinemia that followed the liberal application of Cetacaine for ERCP. All patients recovered after appropriate treatment but these cases serve to highlight the potential problem, the importance of early recognition and treatment, and the most appropriate treatment options.     

Thalmic vaciuation in acute Wernicke's encephalopathy

Two patients with acute Wemicke's encephalopathy, with the diagnosis confirmed pathologically at autopsy, showed substantial vacuolation and neuronal degeneration in discrete nuclei of the thalamus. Thalamic vacuolation has not been described previously in acute Wernicke's encephalopathy. The use of frozen sections to minimize processing artifact was fundamental in demonstrating this pathology. The pathogenic mechanism underlying this change appears to be different to that seen in the more typical periventricular, mamillary body and brainstem lesions. We hypothesize that a specific neural pathway may be involved and suggest that this pathway could be the ascending nitric oxide-containing cholinergic pathway from the brainstem.