Pilot study on the use of basophil activation tests and skin tests for the prevention of allergic transfusion reactions.

Background and objectives: Management of severe allergic transfusion reactions (ATR) is challenging. In this study, we investigate the usefulness of skin tests and basophil activation tests (BAT) in chronically transfused patients for the prevention of future ATR. Materials and methods: BAT and skin tests were carried with the supernatant of red blood cell (RBC) units for a sickle-cell disease patient under chronic exchange transfusion who has presented a severe ATR, in order to prevent potential future ATR. If the results for both BAT and skin tests were negative, the RBC units could be transfused to the patient. If either one of the results was positive, the tested RBC unit was discarded for the patient. Results: 192 RBC units were tested with both tests. The level of results concordance between the two tests was 95%. Out of the 169 negative units with both tests, 118 units were transfused to the patient for which he presented no ATR. Conclusion: In our study, combining both BAT and skin tests was associated with a good negative predictive value since we were able to safely transfuse our patient. Further studies are still necessary to confirm this result but this pilot study indicates that skin tests and BAT might help prevent ATR. When BAT is not available, skin tests may also be useful in preventing ATR.

Disseminated histoplasmosis diagnosed by cross-reactivity with the Aspergillus galactomannan antigen in an HIV-positive patient.

Invasive histoplasmosis is the most common AIDS-defining event in endemic regions such as South America. In non-endemic regions, less familiar to the diagnosis, invasive histoplasmosis can be mistakenly diagnosed as miliary tuberculosis leading to a high mortality rate. Here we present the case of an invasive histoplasmosis mistakenly diagnosed as tuberculosis. The diagnosis of histoplasmosis was considered later on, in light of patient's clinical deterioration and positive Aspergillus galactomannan antigens. This case highlights the importance of considering other opportunistic infections when facing a culture-negative miliary tuberculosis without clinical improvement despite anti-tuberculosis therapy. It also draws our attention to the tools available in non-endemic regions that can be helpful in the diagnosis of invasive histoplasmosis.

Optic neuritis in lung adenocarcinoma: A challenging diagnosis.

Optic neuritis with CRMP-5 IgG is a paraneoplastic inflammation of the optic nerve associated with lung cancer, mostly small-cell lung cancer. We present the case of a patient with lung adenocarcinoma who developed progressive bilateral visual loss a few months after immune-chemotherapy with pembrolizumab and after Covid-19 vaccination. Positive CRMP-5 IgG were detected in blood sample and complete work-up - including brain MRI - did not show any progression. High dose systemic corticoids were administered with transient improving, followed by intravenous immunoglobulins, methotrexate and rituximab but despite negativization of CRMP-5 IgG, the patient had a progressive visual loss.