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Screening patients at high risk of glucose-6-phosphate dehydrogenase (G6PD) deficiency (individuals of African and Mediterranean descent) is recommended prior to initiation of rasburicase. However, a high index of suspicion of G6PD deficiency is also crucial in a patient who develops methaemoglobinaemia or haemolytic anaemia following rasburicase therapy, irrespective of ethnic origin. We report a 56-year-old Hispanic male with mantle cell lymphoma with bulky lymphadenopathy who presented to the emergency department with dyspnoea and chest discomfort. Forty-eight hours prior to presentation, he had received chemotherapy with R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone) with pegfilgrastim support and two 6 mg doses of intravenous rasburicase for the prevention of tumour lysis syndrome. Physical examination was unremarkable. Oxygen saturation (SpO2) was 85% on 100% oxygen via a non-rebreather mask at 10 l/min. Arterial blood gases showed a partial oxygen pressure (PaO2) of 216 mmHg. A full blood count showed haemoglobin concentration (Hb) 93 g/l and white blood cell count 77·9 × 109/l (0·8% lymphocytes). Serum creatinine was 73·37 μmol/l, uric acid 35·69 μmol/l and methaemoglobin 8·4%. Because of the presence of methaemoglobinaemia, intravenous methylene blue was administered. Eight hours later, the patient complained of diaphoresis and light-headedness. SpO2 had dropped to 80% and Hb to 66 g/l. Total and direct bilirubin were 41·05 and 6·84 μmol/l respectively, haptoglobin was less than 10 mg/l and lactate dehydrogenase was elevated at 864 u/l (normal range 94–202), consistent with acute haemolytic anaemia. A peripheral blood film showed irregularly contracted cells and retraction of haemoglobin from the red cell membrane (left). Heinz bodies were demonstrated on supravital staining with new methylene blue (right). The patient was managed with supportive treatment and four units of packed red blood cells were transfused. By 24 h, methaemoglobin levels had dropped to zero. The suspicion of G6PD deficiency was confirmed by enzyme assay with an enzyme level of 1·5 u/g Hb (8·8–13·4). G6PD deficiency is associated with NADPH deficiency, and methylene blue is dependent on NADPH to reduce methaemoglobin to haemoglobin. This renders methylene blue ineffective in G6PD-deficient patients, and it may aggravate methaemoglobinaemia at high doses by oxidizing haemoglobin. Its use should be avoided.

Patient: Female, 91Final Diagnosis: Low-grade gastric MALT lymphomaSymptoms: Recurrent epigastric and right upper quadrant dyscomfortMedication: RituximabClinical Procedure: esophagogastroduodenoscopy • gastric biopsySpecialty: GastroenterologyObjective:Unusual or unexpected effect of treatmentBackground:Mucosa associated lymphoid tissue (MALT) lymphoma can occur in any extranodal organ or tissue, stomach being the common site. Most of the gastric MALT lymphomas are related to chronic H. pylori infection. H. pylori negative gastric MALT lymphoma is relatively uncommon and usually treated with a short course of chemotherapy, radiotherapy or surgery.Case Report:Herein, we present a case of an elderly female with H. pylori negative, low-grade gastric MALT lymphoma that was successfully treated with a short course of rituximab.Conclusions:This case report emphasizes that rituximab monotherapy can be an effective treatment for H. pylori negative low grade gastric MALT lymphoma especially in an elderly patient where surgery or radiotherapy may not be appropriate.

ABSTRACTGeographic Information Systems (GIS) enable decision makers to view tabular data geographically, as maps. This simple yet powerful visual format appears to facilitate problem solving, yet how it does so is not clear, nor do we know the types of problems that benefit from this representation. To begin to understand the contributions of geographic representations over tabular representations, we conducted a three‐factor experiment in problem solving. The experiment contained two different representations (map and table), three different geographic relationships (proximity, adjacency, and containment), and three levels of task difficulty (low, medium, and high). We found that maps generally produced faster problem solving than tables, and that problem‐solving time increased with task difficulty. Most importantly, for the proximity and adjacency geographic relationships we found that maps kept problem‐solving time low, while tables tended to increase time dramatically. However, we found that the number of knowledge states for each task explains performance times quite well and is a useful tool for understanding performance differences and interaction effects. As tasks become more difficult, representing them as maps generally keeps the number of knowledge states small, while for tables, the number of knowledge states increases dramatically. Correspondingly, problem‐solving times increase dramatically with tables, but not with maps.In sum, as difficulty increases, maps are more effective for problem‐solving tasks. Using maps, the tasks are simplified using visual heuristics that keep problemsolving times and error rates from rising as quickly as they do with tables.