A 66-year-old female was admitted to the hospital on October 26th, 2019, with edema of the eyelid and lower limbs for 1 month. 2 weeks ago, edema was aggravated, accompanied by increased foam in urine, nausea, abdominal distension, and poor appetite. Previous history: More than 10 years of type 2 diabetes, blood glucose was controlled satisfactorily. Hypertension has a history of more than 10 years, with poorly controlled blood pressure. A history of chronic bronchitis for many years. Physical examination disclosed an anemic appearance, moderate pitting edema of eyelids and lower limbs. Blood pressure was 176/92 mmHg, and serum glucose level was 5.4 mmol/L. Proteinuria was 22.224 g/24 h, serum albumin was 19.2 g/L, serum creatinine was 233.2 μmol/L, accompanied by hyperlipidemia (triglyceride: 10.10 mmol/L, Cholesterol: 13.65 mmol/L) and significantly increased erythrocyte sedimentation rate (ESR, 103 mm/h). Serum complement 3 (C3) level was in normal range, and C4 level was slightly high (41.2 mg/dL). Serum protein electrophoresis showed no M-spike. Coagulation function and thyroid function were normal. Antinuclear antibodies (ANA), anti-double-stranded DNA antibody, anti-neutrophil cytoplasmic antibody (ANCA) and anti-phospholipase A2 receptor (PLA2R) antibody were negative. Tests of hepatitis B surface antigen, antibodies against hepatitis C virus and human immunodeficiency virus were negative. Immunoglobulin examination revealed markedly elevated IgE level (7080 IU/mL, normal range 0-165 IU/mL), slightly decreased IgG level (505 mg/dL). IgA and IgM levels were normal. Mild abnormalities were found in serum light chain tests (κ chain: 114.69 mg/dL, λ chain: 64.41 mg/dL), but the ratio of κ to λ was normal (κ/λ:1.78). Both level of Ca125 and Ca199 were elevated (188.92 U/mL, and 48.65 U/mL, individually). Abdominal ultrasound indicated that the size and shape of the kidney was normal. There was a hypoechoic mass (5.0 cm × 3.0 cm × 4.1 cm) near the upper part of the right kidney. Computerized tomography (CT) scan for the abdomen revealed a space occupying lesion between the gastric antrum and the duodenum. Gastroscopy (November 13rd, 2019) showed that the proximal end of the posterior duodenal bulb had a raised lesion about 2.0 cm in size. The pathological result of gastroscope biopsy was inflammation. Kidney biopsy was performed. Of 10 glomeruli, 3 were globally ischemic sclerosed. Glomerular mesangium was normal. No nodular glomerulosclerosis, microaneurysm, hyaline insudation, crescent and capsule adhesion was seen. There was mild tubular atrophy, mild interstitial edema, inflammation and fibrosis in tubulointerstium. Tubular epithelial necrosis and brush border loss was occasionally observed. Arteries and arterioles exhibited mild intimal fibrosis and hyalinosis. Immunofluorescence microscopy for immunoglobulins G, A, and M, C3, C4, C1q, and fibrinogen was negative. It was observed by electron microscopy that there was no electron-dense deposits, the thickness of GBM was normal (343 nm ~ 405 nm, average 382 nm), and foot process of podocyte was widespreadly effaced. MCD and subacute tubulointerstitial injury was diagnosed (Fig. 1). The patient was discharged after remission under treatments including diuresis, antihypertensive treatment, blood glucose control, and anemia correction. We observed quickly decline of proteinuria (2.514 g/24 h), with serum albumin level elevated to 31.5 g/L, serum IgE level decreased to 6540 IU/mL and serum creatinine decreased to normal.
On May 10th, 2020, the patient was readmitted for review. Proteinuria was 2.579 g/24 h and serum albumin was 34.1 g/L. But the serum IgE level went up to 8530 IU/mL. Abdominal enhanced magnetic resonance imaging (June 2nd, 2020) disclosed that the intestinal wall of the descending junction area of the duodenum was thickened, with a range of about 47 mm × 61 mm, lymphoma was not excluded. Electronic ultrasound endoscopy was performed again on June 8th, 2020. A 1.0 cm × 1.5 cm deep ulcer was found in the upper part of the descending duodenum. The tumor was located in the posterior lateral wall of the descending duodenum, with a range of about 4.5 cm × 3 cm × 3 cm. The pathologic diagnosis of the tumor was duodenalgastrointestinal stromal tumor (GIST), spindle cell type, low-risk type. Only one mitose was observed per 50 HPF (Fig. 2A). Immunoperoxidase staining for CD117 (c-kit), Dog-1, and Vimentin were positive in the tumor cells (Fig. 2B), while staining for CD34, smooth muscle actin (SMA), desmin and S-100 were negative. The positive ratio of Ki-67 staining was lower than 10%. On June 24st, 2020, the patient was administrated with imatinib mesylate (400 mg/day), and the surgical excision of the tumor was performed after 1 month. Imatinib mesylate has been administered subsequently. The histopathological result of the tumor was also duodenal GIST (spindle cell type, and low-risk type). The patient had never received any specific immunosuppressive therapy for proteinuria. Proteinuria slowly declined to 0.846 g/d 1 month after surgery, with serum albumin increased to 36.4 g/L and IgE decreased to 2900 IU/mL. 2 months after surgery, proteinuria was 0.86 g/d, serum albumin was 36.3 g/L and serum IgE was 2100 IU/mL. Eight months after surgery, proteinuria was 0.719 g/d, serum albumin was 45.3 g/L (Fig. 3A) and serum IgE was 1360 IU/mL (Fig. 3B).