The case analyzed herein was an 82-year-old female patient with a history of colonic diverticulosis and cerebral aneurysm (10 mm in size, no treatment). She denied any tobacco use or alcohol consumption, but she mentioned allergies to doxycycline and amoxicillin. No deterioration of renal or cardiac function had been reported in her previous medical examinations. Family history was unremarkable, too. She had received the first and second doses of BNT162b2 vaccine for COVID-19 in June 20XX. On July 8, 20XX, she noticed that her neck had become thicker, so she visited a local cardiologist on July 15; furosemide 40 mg per day was prescribed for suspected renal and cardiac insufficiency. On July 26, she consulted the local urologist, who prescribed azosemide 30 mg, although no improvement in her oedema was observed. On July 29, she was referred to our hospital for further examination and treatment for suspected heart failure and she was admitted for further diagnostic testing and treatment because of marked oedema, worsening renal function with serum creatinine 1.98 mg/dL and a decreased platelet count of 4.0 × 104 /μL. On admission, her clinical findings were as follows: blood pressure, 112/92 mmHg; heart rate, 96/min; axillary temperature, 37.1 °C; body height, 153 cm; and body weight, 44.7 kg (body mass index 19.1 kg/m2). She had severe oedema of the lower extremities and superficial lymph nodes in the cervical, axillary and inguinal regions could be palpated. No arthralgias, neurologic findings, or skin lesions were noted. Furthermore, heart and lung examinations were normal. Blood test results on admission showed renal dysfunction, low platelets, and elevated inflammatory markers; an infection was initially on top of the differential diagnosis. However, since generalized oedema, cardiac enlargement and pleural effusion on chest radiograph were not consistent with the course of an infection, antibiotics were not started. A computerized tomography scan taken on admission showed enlarged bilateral cervical, axillary and intra-abdominal lymph nodes, mild hepatomegaly and splenomegaly. The clinical course is shown in Fig.. Chest X-ray and computerized tomography images taken on 6th day of hospitalization revealed significantly increased pleural effusion. In addition, the patient gained > 5 kg of body weight, her urine output decreased, and fluid control with diuretics was difficult, so a non-cuffed catheter was inserted through the right femoral vein, and hemodialysis was started. Diuretic-resistant oedema, worsening pleural effusion, and progressive thrombocytopenia were observed, and TAFRO syndrome was suspected at this point. Human herpesvirus 8 and peripheral blood smears were not tested in this case. On the 13th hospital day, biopsies of a left axillary lymph node and bone marrow were performed; no findings compatible with infection and malignancy were observed. As a result, a pulse therapy with 500 mg of methylprednisolone was administered from the 14th day for 3 days, followed by 50 mg of prednisolone daily. Mild fibrosis and megakaryocytosis were present in bone marrow biopsy. The lymph node biopsy revealed Castleman-like findings, and the patient was diagnosed with TAFRO syndrome according to the diagnostic criteria proposed in 2019 []. After starting prednisolone, although her urine output increased, this was not sufficient, and her platelet count was dependent on platelet transfusions. Considering the effect of these treatments insufficient, we started her on 100 mg of cyclosporine on the 23rd day. A pleural fluid examination was performed on the 33rd day to determine the pleural fluid component, which was a leaky pleural effusion. The dose of cyclosporine was increased to 125 mg on the 43rd day based on therapeutic drug monitoring. The prednisolone dose was reduced by 5 to 10 mg every week or two. The patient was weaned from dialysis on the 34th day of hospitalization because her urine output had stabilized, and her platelet count began to increase on the 51st day. Since the platelet count increased independently of transfusion, a renal biopsy was performed on the 58th day. The renal biopsy results revealed membranous proliferative glomerulonephritis (MPGN) findings consistent with TAFRO syndrome. Immunofluorescence staining was positive for immunoglobulin (Ig)A and complement 3 and negative for IgG, IgM, and Fibrinogen. The electron micrograph revealed oedematous enlargement of the subendothelial space. The edematous changes in the mesangial area were observed, although no electron-dense deposits were detected. After renal biopsy, eltrombopag 25 mg, a thrombopoietin receptor agonist, was administered to the patient, causing a sustained increase in platelet count, and the patient was discharged on the 108th day. At the time of discharge, the patient was taking 12.5 mg of prednisolone and 125 mg of cyclosporine.