Defining the clinical-radiological and anatomopathological phenotypes of persistent COVID in immunocompromised patients

<bold>Background</bold> - In immunocompromised hosts with COVID-19, the impairment of viral clearance mechanisms predisposes to persistent virus infection. Misdiagnosis of this condition leads to the prescription of inappropriate therapies and clinical deterioration of patients. We sought to characterize clinical-radiological and anatomopathological phenotypes of persistent COVID in immunocompromised patients, aiming to identify some keypoint useful for outlining a pragmatic diagnostic pathway for clinicians. <bold>Methods</bold> - We conducted a retrospective observational study to assess the management of a sample of immunocompromised hosts with persistent COVID hospitalised in the Careggi University Hospital (Florence) along with a literature review. <bold>Results</bold> - We collected 15 immunocompromised hosts (7 males, 46%), the median age was 58 yr [43 – 66]. 8(53%) patients with haematological malignancies and 7(46%) with autoimmune diseases - 73% treated with anti-CD20-. The interval between the infection and the first relapse was 106 days [44 - 214]. 8 patients were symptomatic, and cough was the most reported symptom (75%). During relapses, 14 patients showed non-fibrosing HRTC patterns with GGO/consolidations (1 previous ILD) and perilobular GGOs or OP pattern was the most striking finding (40%). We performed BAL in 14 patients (all detected viral RNA), 6 showed marked CD8+ lymphocytosis in the immunophenotype analysis. 1 patient underwent cryobiopsy, which showed a cellular NSIP pattern. <bold>Conclusions</bold> - Our analysis emphasizes the role of SARS-CoV-2 in clinical relapses among immunocompromised hosts, providing practical diagnostic tools for clinicians facing challenging differential diagnosis.