Membranoproliferative glomerulonephritis-like findings for TAFRO syndrome, associated with an anterior mediastinal tumor: A case report

Abstract

Rationale: TAFRO syndrome is a systemic inflammatory disease proposed recently from Japan. The cause of TAFRO syndrome is unclear. Moreover, the disease characteristics and kidney pathology are yet unknown well and there are few cases. Herein, we report a patient with TAFRO syndrome and present the features of the renal histopathology.

Patient concerns: A 55-year-old woman presented to our hospital with the main complaint of subacute dyspnoea.

Diagnosis: Physical findings included a low-grade fever and generalised oedema. A blood test showed anaemia, coagulation abnormalities, hypoproteinaemia, impaired renal function, proteinuria, and elevated alkaline phosphatase (ALP), C-reactive protein (CRP), interleukin-6 (IL-6). Chest and abdominal computed tomography showed an anterior mediastinal mass and multiple enlarged lymph nodes.

Interventions: Nephrotic syndrome secondary to a malignant mediastinal tumour was suspected; therefore, the patient underwent resection of the anterior mediastinal mass. Histopathological examination of the resected specimen showed lymphocytic proliferation without signs of malignancy. These findings were compatible with hyaline vascular type Castleman disease (CD), and with the associated multiple lymph nodes enlargement, the patient was initially diagnosed with multicenteric CD.

Outcomes: After resection of the whole tumour, all the clinical symptoms improved. However, after resection 6 months passed, the patient developed thrombocytopenia, anaemia, renal dysfunction, further enlargement of the residual lymph nodes, hepatosplenomegaly, and mild myelofibrosis. A diagnosis of TAFRO syndrome (TS) was eventually made. All symptoms improved with initial intravenous pulse steroid therapy followed by oral steroids. Histopathological examination of the renal biopsy samples showed findings resembling membranoproliferative glomerulonephritis (MPGN).

Lessons: In TS, all characteristic signs may not exist from the beginning. The association between TS and CD is not clear. When we compared our findings with previously published cases of TS and CD, we found that the renal pathology findings resembled MPGN in many cases of TS, while only a few cases showed amyloidosis. Recent results suggest that TS may be an independent disease from CD, and given the frequency of renal pathology findings, it may also have a different aetiology. To the best of our knowledge, this case report is rare to demonstrate the renal pathology in a patient with conventional TAFRO syndrome.

Figure 1

Computed tomography scan of the chest and abdomen.

Figure 2

¹⁸FDG-positron emission tomography scan showing abnormal accumulation of FDG in the lymph nodes.

Figure 3

Gross appearance of the anterior mediastinal tumor. The anterior mediastinal tumor measured 65 × 25 mm and showed a multinodular lesion with fibrosis.

Figure 4

Light microgram showing the histological findings of the anterior mediastinal tumor × 20 hematoxylin–eosin stain.

Figure 5

Light microgram showing the bone marrow findings × 100 Silver impregnation method: Mild fibrosis.

Figure 6

Treatment course. In this figure, the progression and the change of each clinical parameter with steroid therapy is illustrated. As shown, improvement of the different parameters was observed with steroid therapy. ALP = alkaline phosphatase (IU/L), BW = body weight (Kg), CRP = C-reactive protein (mg/dL), eGFR = estimated glomerular filtration rate (mL/min/1.73 m²), Hb = hemoglobin (g/dL), IL-6 = interleukin-6 (pg/mL), LDH = Lactate dehydrogenase (IU/L), Ope = Operation, PSL = prednisolone, UP = urine protein (mg/gCr), VEGF = vascular endothelial growth factor (pg/mL).

Figure 7

Renal histopathological findings. (A) Light microgram × 400 hematoxylin–eosin stain, (B) ×400 periodic acid silver-methenamine stain, (C) ×1000 periodic acid silver-methenamine stain, (D) Fluorescent antibody technique ×20 IgM, (E) electron micrograph ×5000.