To report the case of a patient diagnosed with Chylothorax secondary to LPD.

Assessment of patient's information kept on HSPE computer-based patient records. Case report: 67-year-old-male with lymphocytosis in peripheral blood in Mar/2016. Complete blood counts:Hb 8.8 g/dL, WBC 38,850/mm3, 92% of lymphocytes (Ly) and no other signs of active disease. Bone marrow flow Cytometry (FC) with 77% of anomalous B Ly (BLy) positive for CD19, CD20, CD22, CD38, CD200, FMC7, IgM and Lambda free light chain (FLC); negative for CD5, CD10, CD11c, CD28, CD103 and Kappa FLC. Matutes score 0. He was diagnosed with LPD and followed up closely. Six months later, he progressed with a history of low-grade fever, weight loss and nocturnal drenching sweats. He was started on Rituximab for 4 cycles in April/2017, followed by 12 cycles (maintenance), achieving disease control. In Feb/22, he got COVID-19 and presented with persistent respiratory symptoms, including dyspnea and dry cough. Thoracic CT scan revealed large right pleural effusion with no thrombosis. Analysis of pleural effusion showed a chylothorax pattern. Abdominal CT scan showed some lymph nodes enlargement (max. 2.3cm). He underwent thoracic drainage due to persistent dyspnea and low oxygen saturation. Pleural fluids built up quickly after drainage. He was submitted to lymphography and embolization of thoracic duct, building up pleural effusion once again a couple of days later. At that time, we considered he had active LPD after pleural effusion FC showed mature BLy positive for CD19, CD20, lambda FLC, CD79b, CD200, CD23, FMC7 and negative for CD5, CD10, CD11c. He was treated with Rituximab, Cyclophosphamide, Vincristine and Prednisone (R-CVP), after which he had complete resolution of the effusion and has been followed up regularly. Discussion: Chylothorax is a rare condition caused by the leak of chyle into the pleural cavity. Malignancies are the most common non-traumatic causes of chylothorax, as a result of infiltration of lymphomatous cells or compression by enlarged lymph nodes. It is defined by pleural fluid triglyceride levels >110 mg/dL, presence of chylomicrons, and low cholesterol level. Fifty percent of cases are due to traumas/surgeries while 39% are due to malignancies. Sarcoidosis and Tuberculosis are also possible causes. Lymphatic anomalies may be involved. As stated by Satriano et al. there are few reports on chylothorax related to COVID19 infection, along with thrombotic events. SARSCoV2 infection can cause cytokine storms with consequent hyperinflammation and arterial and venous vasculopathy associated with a prothrombotic state. Our patient didn't have any thrombotic event. Currently, there is no general standard therapy for such cases, so the correct approach (drainage, surgeries, drugs/chemotherapy) should be taken in regards to the causative injury.

this case illustrates well how diverse LPD's manifestations can be. LPD needs to be considered every time a non-traumatic chylothorax appears, especially when there is already a history of malignancies, even though it's a rare condition. Despite his previous COVID-19 diagnosis, our patient didn't present any clear vascular injury which made us find it hard to explain his pleural effusion as secondary to that infection. After having been treated with R-CVP, he's still in disease remission up to this point.