The patient, a 61-year-old male, was admitted to the hospital after three months of the following symptoms: cough, dyspnea, and swelling of the double mandibular lymph nodes and both eyelids. A CT scan revealed a mass in the left kidney. The patient had undergone a submandibular lymph node biopsy 13 years ago due to bilateral submandibular tumors, which indicated reactive lymph node hyperplasia. However, there was no further diagnosis and the patient was not treated. Seven years ago, the patient experienced bilateral mandibular enlargement and bilateral eyelid enlargement and was subsequently diagnosed with IgG4-related sialadenitis at Peking University Stomatological Hospital. Examining the pathology results under a microscope showed the structure of the right submandibular lymph node. Typically, normally distributed lymphatic follicles and lymphatic sinuses are observed in the lymph nodes, but in this case, the lymphoid follicles were slightly increased. There were more lymphocytes, plasma cells, and scattered infiltration observed in the salivary glands of the right submandibular gland, with interstitial fibrosis. Immunohistochemistry was partially positive for IgG and net positive for IgG4NS and CD21FDC. A kidney color Doppler ultrasound prompt showed no obvious abnormalities in either kidney. Results from a blood test showed IgG levels of 19.38 g/L. The swelling of both jaws and bilateral lacrimal glands significantly decreased after six days of intravenous methylprednisolone treatment. After discharge, the patient regularly took hormonal drugs (prednisone acetate) for three years, and irregularly took Imulan for four years. Three years ago, the patient’s IgG4 was measured at 3.11 g/L. The patient stopped taking Imulan of his own accord seven months prior to his most recent hospitalization, which was due to the recurrence of double mandibular swelling, bilateral eyelid swelling, coughing, and dyspnea which re-appeared three months ago. He was admitted to the rheumatology department of The First Hospital of Jilin University. A blood test showed 12.4 g/L IgG4, and the tumor markers showed no obvious abnormalities. Upon admission to the hospital, the patient was administered intravenous methylprednisolone for four days, significantly improving his symptoms. The patient was later transferred to the Department of Urology after a CT scan showed a tumor in his left kidney. We re-checked his IgG4 levels, which were 10.1 g/L, and administered 30 mg oral prednisone acetate each day.
Ultrasound examination of the kidney: A mixed mass of 2.0×1.8cm in the upper parenchyma of the left kidney was observed, with unclear boundaries. No obvious blood echo was observed inside or around the mass. The results of a kidney CT plain scan and three-phase enhancement detection showed a nodular, slightly low-density shadow on the posterior part of the upper pole of the left kidney (Figure 1.A), about 2.2×2.9cm in size, and an unevenly enhanced cortical phase (Figure 1.B). We observed reduced degrees of enhancement in both the medullary phase (Figure 1.C) and the secretory phase (Figure 1.D).
PET-CT results showed a convex nodule with a size of 1.6×2.1cm behind the upper pole of the left kidney (Figure 1.E), with a maximum SUV value of 1.5. This indicates that the nodule in the upper pole of the left kidney shows mild FDG uptake, meaning kidney cancer was not excluded.
Preoperative diagnosis: left kidney tumor.
The patient underwent retroperitoneal laparoscopic partial resection of the left nephron with the preserved nephron. Pathological results suggested clear cell renal cell carcinoma in the left kidney (grade 3 according to the WHO/ISUP nuclear grade standards, 2016 edition).
The tumor volume was 2.5×1.8×1.8cm. Vessels and nerves had no clear cancer infiltration. No cancer was observed on the margin of the surgically removed kidney tissue. A small amount of lymphocyte infiltration was observed in the renal parenchyma around the tumor. According to the 2017 AJCC, the patient's tumor stage was T1a.
Immunohistochemical results showed that IgG4 protein/Ig protein>40% in the plasma cell. Mum-1 (+) histopathology showed that the tumor was a classic clear cell renal cell carcinoma and that the tumor cells had clear cytoplasm surrounded by a fine fiber vascular network (Figure 2.A). A focal lymphocyte aggregation area was observed outside the tumor capsule, which is composed of lymphocytes and plasma cells (Figure 2.B). Mum-1 immunohistochemical staining showed more plasma cells were scattered in the lymphocyte aggregation area (brown and nuclear positive, indicating plasma cells) (Figure 2.C). IgG4 immunohistochemical staining and lymphocyte aggregation areas are scattered in IgG4-positive cells (brown, cytoplasmic positive cells indicate IgG4 secreting plasma cells), while the ratio of IgG4 in IgG cells in the comparison section exceeded 40% (Figure 2.D).
The post-operative patient recovered without complications and was subsequently discharged. On the first day after the operation, the patient was given intravenous methylprednisolone for three days instead of oral prednisone acetate. At this point, the swelling of the patient’s jaws and eyelids was significantly relieved, and the symptoms of cough and dyspnea significantly subsided. Following the switch to oral prednisone acetate, the patient’s IgG4 was 5.92 g/L when rechecked four days after surgery. Methylprednisolone was subsequently changed to prednisone acetate. Following his discharge from the hospital, the patient was instructed to visit the rheumatology department for further treatment. The patient returned to our hospital two months after the operation, and we found that he recovered without postoperative complications.