Syndrome confusionnel et anémie hémolytique au retour d’outre-mer

Case Report: Leishmania and HIV Co-Diagnosis: How to Understand Medical History?

We report a case of a severe visceral leishmaniasis revealing an HIV-1 infection presenting as an acute primary infection. A young French man living in Paris with history of unprotected sex with a recent male partner and recent travel in Greece was admitted in our Infectious Diseases Department, presenting with acute febrile psychotic disorder, and positive HIV-1 serology with high viral load, very low CD4⁺ T-cells count and a western blot pattern suggesting an acute infection. The psychotic disorder was finally related to hemophagocytic lymphohistiocytosis diagnosed on bone marrow aspiration, supposedly secondary to HIV acute primary infection. The progressive worsening of pancytopenia despite antiretroviral treatment and the persistence of fever, chills and sweat led to the diagnosis of visceral leishmaniasis through bone marrow biopsy and leishmanial serology. He was treated with intravenous liposomal amphotericin B with quick improvement. We discuss the way HIV infection and visceral leishmaniasis may have interact to lead to the clinical presentation of our patient.

STXBP2-R190C Variant in a Patient With Neonatal Hemophagocytic Lymphohistiocytosis (HLH) and G6PD Deficiency Reveals a Critical Role of STXBP2 Domain 2 on Granule Exocytosis

Neonatal hemophagocytic lymphohistiocytosis (HLH) is a medical emergency that can be associated with significant morbidity and mortality. Often these patients present with familial HLH (f-HLH), which is caused by gene mutations interfering with the cytolytic pathway of cytotoxic T-lymphocytes (CTLs) and natural killer cells. Here we describe a male newborn who met the HLH diagnostic criteria, presented with profound cholestasis, and carried a maternally inherited heterozygous mutation in syntaxin-binding protein-2 [STXBP2, c.568C>T (p.Arg190Cys)] in addition to a severe pathogenic variant in glucose 6-phosphate dehydrogenase [G6PD, hemizygous c.1153T>C (Cys385Arg)]. Although mutations in STXBP2 gene are associated with f-HLH type 5, the clinical and biological relevance of the p.Arg190Cys mutation identified in this patient was uncertain. To assess its role in disease pathogenesis, we performed functional assays and biochemical and microscopic studies. We found that p.Arg190Cys mutation did not alter the expression or subcellular localization of STXBP2 or STX11, neither impaired the STXBP2/STX11 interaction. In contrast, forced expression of the mutated protein into normal CTLs strongly inhibited degranulation and reduced the cytolytic activity outcompeting the effect of endogenous wild-type STXBP2. Interestingly, arginine 190 is located in a structurally conserved region of STXBP2 where other f-HLH-5 mutations have been identified. Collectively, data strongly suggest that STXBP2-R190C is a deleterious variant that may act in a dominant-negative manner by probably stabilizing non-productive interactions between STXBP2/STX11 complex and other still unknown factors such as the membrane surface or Munc13-4 protein and thus impairing the release of cytolytic granules. In addition to the contribution of STXBP2-R190C to f-HLH, the accompanied G6PD mutation may have compounded the clinical symptoms; however, the extent by which G6PD deficiency has contributed to HLH in our patient remains unclear.

Adult haemophagocytic syndrome

Haemophagocytic syndromes (haemophagocytic lymphohistiocytosis) have a wide range of causes, symptoms, and outcomes, but all lead to a hyperinflammatory response and organ damage--mainly reported in paediatric patients, but reports of adult presentation are increasing. Analysis of the genetic and molecular pathophysiology of these syndromes have improved the understanding of the crosstalk between lymphocytes and histiocytes and their regulatoty mechanisms. Clinical presentations with a broad differential diagnosis, and often life-threatening outcome, complicate the management, which might include supportive intensive care, immunosuppressive and biological treatments, or haemopoietic stem cell transplantation. Insufficient knowledge of these syndromes could contribute to poor prognosis. Early diagnosis is essential to initiate appropriate treatment and improve the quality of life and survival of patients with this challenging disorder.