Methods
Blood exams revealed increased levels of serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyl transferase (GGT), lactate dehydrogenase (LDH), D-Dimer, high-sensitivity troponin (stable after 3 hours). Arterial blood gas analysis was normal and SARS Cov-2 RNA testing of the swab was negative. Chest X-Ray documented thickened smoothly interlobular septae in the right parahilar, subtle parenchymal hypodiaphania on the left basal area and blunting of the costophrenic angles. After blood cultures and swabs collection for St. Aureus Methicillin-Resistent , empiric antibiotic therapy with piperacillin/tazobactam and daptomycin was then started. Compression ultrasonography of lower extremity outlined partial and segmental incompressibility of the right popliteal vein compatible with subacute deep vein thrombosis (DVT) with partial recanalization. DVT treatment with low-molecular-weight heparin was immediately started. Upon admission to our Unit the patient was in fair clinical condition. His heart rate was still 95 bpm and ABP was 110/60 mmHg. On physical examination, grade 2/6 systolic murmur localized to the area of the left sternal border and bilateral basal crackles were documented; vesicular breath sounds were diminished. Further blood exams showed hypoalbuminemia (15 g/l), hypoproteinemia (50 g/l) and decreased levels of antithrombin III (<60%). Electrocardiography showed low QRS voltage in precordial leads while echocardiography documented hypertrophic cardiomyopathy and thickened interventricular septum. Serum protein electrophoresis showed a band in β1 globulin region; on immunofixation electrophoresis, serum revealed IgA lambda monoclonal component (16 g/l) (Figure 1) . The 24-h proteinuria was 6,4 g and Bence-Jones protein was detected in the urine. Serum IgA was higher than normal range (12,75 g/l). Total body computed tomography (CT) scan showed bilateral pleural effusion and small pericardial effusion (6 mm). In the suspicion of amyloidosis, despite the negativity of the abdominal fat pad fine-needle aspiration biopsy, myocardial scintigraphy and magnetic resonance (MRI) were then performed. Scintigraphy (and genetic testing) was negative for the ATTR subtype. Cardiac MRI revealed asymmetric, non-obstructive and hypertrophic cardiomyopathy, thickened interventricular septum (20 mm), and circumferential late gadolinium enhancement in the sub-mesocardial area, indicating amyloid accumulation (Figure 2 ). Finally, kidney biopsy showed Congo red positivity on light microscopy; while immunohistochemistry for anti-lambda antibodies was positive, confirming light-chain (AL) amyloidosis. Based on the patient’s anamnesis, reporting unprotected sex and recurring fever over the last few months, microbiological investigations were performed, revealing chronic hepatitis B infection (serum HBV DNA level of >95 million copies/ml), EBV DNA infection and HIV infection (serum HIV RNA level of >2 million copies/ml). Lymphocyte subpopulation analysis showed lower CD4+ (208/μL), and CD4/CD8 ratio of 0.10. Quantiferon-TB Gold was negative.