Histiocytic hyperplasia with hemophagocytosis and acute alveolar damage in COVID-19 infection.

The spectrum of COVID-19 infection includes acute respiratory distress syndrome (ARDS) and macrophage activation syndrome (MAS), although the histological basis for these disorders has not been thoroughly explored. Post-mortem pulmonary and bone marrow biopsies were performed in 33 patients. Samples were studied with a combination of morphological and immunohistochemical techniques. Bone marrow studies were also performed in three living patients. Bone marrow post-mortem studies showed striking lesions of histiocytic hyperplasia with hemophagocytosis (HHH) in most (16/17) cases. This was also observed in three alive patients, where it mimicked the changes observed in hemophagocytic histiocytosis. Pulmonary changes included a combination of diffuse alveolar damage with fibrinous microthrombi predominantly involving small vessels, in particular the alveolar capillary. These findings were associated with the analytical and clinical symptoms, which helps us understand the respiratory insufficiency and reveal the histological substrate for the macrophage activation syndrome-like exhibited by these patients. Our results confirm that COVID-19 infection triggers a systemic immune-inflammatory disease and allow specific therapies to be proposed.

Evaluation of the SAMe-TT2R2 score to predict the quality of anticoagulation control in a cohort of patients with venous thromboembolism treated with vitamin K antagonists.

OBJECTIVE: The SAMe-TT2R2 score has been recently proposed to predict the quality of anticoagulation control in patients with atrial fibrillation treated with vitamin K antagonists (VKA). We aimed at calculating this score in a cohort of patients with Venous Thromboembolism (VTE) and determine its usefulness. METHODS: We included all consecutive patients with VTE treated with VKA for >90days. We collected all variables included in the score (female sex, age<60years, medical history [>2 comorbidities], treatment [interacting drugs: e.g. amiodarone], tobacco [doubled], race [doubled]) and analyzed the relationship between the SAMe-TT2R2 score and time in therapeutic range (TTR), determined by the Rosendaal method and by the percentage of INR determinations (after excluding the first month). RESULTS: 135 patients were treated with VKA for >90days, with a median TTR 65%. No differences in INR controls within range were found between patients with score 0-1 vs ≥2 (64.7±19.5% vs 66.0±20.5%, p=0.728). No differences were found in INR controls above (21.5±18.1% vs 21.2±21.3%, p=0.605) or below (3.9±14% vs 2.9±15.9%, p=0.517) the therapeutic range. CONCLUSION: The SAMe-TT2R2 score is not useful to predict quality of anticoagulation control in patients with VTE treated with VKA.