|Year : 2020 | Volume
| Issue : 5 | Page : 1148-1150
Renal pseudotumor: A new challenge in the diagnosis of immunoglobulin G4-related disease
Qian Wu, Na Zhao, Xia Wang, Hongsheng Sun, Limin Zhang
Department of Rheumatology, Shandong Provincial Hospital Affliated to Shandong First Medical University, Jinan, Shandong Province, China
|Date of Submission||26-May-2020|
|Date of Decision||03-Aug-2020|
|Date of Acceptance||04-Aug-2020|
|Date of Web Publication||29-Sep-2020|
Department of Rheumatology, Shandong Provincial Hospital Affliated to Shandong First Medical University, 324 Jingwuweiqi Road, Jinan, Shandong Province, 250021
Source of Support: None, Conflict of Interest: None
Background: Immunoglobulin G4-related disease (IgG4-RD) is an immune mediated fibro inflammatory condition characterized by abundant IgG4-positive (IgG4+) plasma cell infiltrated lesions and elevated serum IgG4 concentrations. Tubulointerstitial nephritis and glomerular lesions are the most common renal IgG4-RDs. However, solitary mass lesion is rarely observed in renal IgG4-RD.
Materials and Methods: We reported a 55-year-old male patient with a space-occupying lesion in the right kidney detected during a routine ultrasound medical examination. Computed tomography indicated a 20 mm × 15 mm × 18 mm mass located at the lower pole of the right kidney. Both T1-weighted imaging and T2-weighted imaging magnetic resonance imaging scans showed a hypointense mass. Diffusion-weighted imaging (b value = 800) showed slightly hyperintensity.
Results: The lesion was diagnosed as renal cell carcinoma clinically based on the laboratory and radiological findings and treated with laparoscopic resection. However, the postoperative histological examination results indicated the lesion IgG4-RD of the kidney.
Conclusion: We should consider pseudotumor-like IgG4-RD as a differential diagnosis for solitary renal lesion although the incidence is low.
Keywords: Immunoglobulin G4-related disease, inflammatory pseudotumor, kidney
|How to cite this article:|
Wu Q, Zhao N, Wang X, Sun H, Zhang L. Renal pseudotumor: A new challenge in the diagnosis of immunoglobulin G4-related disease. J Can Res Ther 2020;16:1148-50
| > Introduction|| |
Immunoglobulin G4-related disease (IgG4-RD) was first introduced in 2003 as the cause of Type 1 autoimmune pancreatitis, and was then considered to encompass multi-organ inflammatory conditions.,,, The lesions associated with IgG4-RD usually involve multiple organs, including the pancreas, biliary tracts, major salivary glands, retroperitoneum, and lymph nodes. The main clinical features include variable degrees of tissue fibrosis, tumor-like expansions, perivascular lymphocytic infiltration abounded with IgG4-positive plasma cells, and elevated serum IgG4. The diagnostic approach depends on clinical manifestations, IgG4 higher than the normal range, biopsy-confirmed lymphoplasmacytic perivascular infiltrated with storiform fibrosis, obliterative phlebitis, and an abundance of IgG4+ plasma cells. The most common renal manifestations of IgG4-RD are tubulointerstitial nephritis and glomerular lesions., In rare incidences, however, the disease can present as a solitary mass lesion. A lack of comprehensive understanding of this disease can easily lead to a missed diagnosis or misdiagnosis. Herein, we present a rare case of IgG4-RD manifested as a solitary inflammatory pseudotumor in the right renal parenchyma.
| > Case Report|| |
A 55-year-old male patient was referred to our hospital due to a space-occupying lesion in the right kidney detected during a routine ultrasound medical examination. The patient had no previous medical history or family history of kidney disease. The physical examination was normal and the immunoglobulin, complement, and serum IgG4 levels were also within normal range. An abdominal ultrasonography showed a low anechoic mass. Computed tomography (CT) indicated a 20 mm × 15 mm × 18 mm mass located at the lower pole of the right kidney. Contrast enhancement CT suggested a malignant tumor [Figure 1] and both T1-weighted imaging (T1WI) and T2-weighted imaging (T2WI) magnetic resonance imaging (MRI) scans showed a hypointense mass. Diffusion-weighted imaging (b value = 800) showed slightly hyperintensity [Figure 2]. However, no obvious enlarged lymph nodes were found in abdominal cavity and retroperitoneum. The lesion was diagnosed as renal cell carcinoma clinically based on the laboratory and radiological findings, and treated with laparoscopic resection.
|Figure 1: Abdominal computed tomography showing renal tumor was slightly enhanced during the arterial phase of enhancement|
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|Figure 2: On magnetic resonance imaging, the mass represent hypointensity on both T1-weighted imaging and T2-weighted imaging. Diffusion-weighted imaging (b value = 800) represent slight hyperintensity|
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A histologic examination revealed lymphoplasmacytic infiltration in renal cortex. Infiltrating plasma and lymphocytes cells had no significant cytological atypia. The IgG4-positive plasma cells infiltrated exceeded 10 cells per high-power field on immunohistochemical examination. Over 40% of IgG positive plasma cells were positive for IgG4 [Figure 3]. Based on these examination results, we diagnosed the lesion as IgG4-RD of the kidney. The patient did not undergo any additional therapy and the outcome was favorable. His renal function and IgG4 levels remained normal and there was no evidence of IgG4-RD during the following 10 months.
|Figure 3: (a) Histology showing the mass characterized by diffused lymphoplasmacytic infiltration (magnification, ×100) (b) anti immunoglobulin antibody staining showing immunoglobulin positive plasma cells (magnification, ×200) (c) anti immunoglobulin G4 antibody staining showing immunoglobulin G4 positive plasma cells (magnification, ×400). The immunoglobulin G4/immunoglobulin positive cell ratio was >40%|
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| > Discussion|| |
In 2003, Japanese scholars first introduced the concept of IgG4-RD. Since then, the disease has gradually gained wide recognition by medical communities in multiple countries. The main clinical features of this disease are masses or diffuse swelling of involved organs or tissues, infiltration of IgG4-positive plasma cells with fibrosis ± obliteration phlebitis, and significant elevation of serum IgG4.,, At present, the diagnosis of IgG4-RD is based on the comprehensive diagnosis standard established in 2011. It should be emphasized that even if the above diagnostic criteria were met, tumors (such as cancer and lymphoma) and similar diseases (such as Sjogren's syndrome, primary sclerosing cholangitis, retroperitoneal fibrosis, Castleman's disease, sarcoidosis, and allergic granulomatous vasculitis) must be excluded before diagnosis.
Clinically, about 15% of IgG4-RD involves the kidney, mainly manifested as tubulointerstitial nephritis, glomerulonephritis, multiple cortical nodules or lumpy lesions, which requires to be differentiated from lymphoma, renal infarction, or metastatic cancer., The isolated unilateral mass involving renal parenchyma was rarely observed in renal IgG4-RD. Shoji et al. reported a 56-year-old female patient with renal lesions detected by ultrasound. CT showed low-density masses while MRI T1WI showed iso-intense and T2WI showed low-intense nodules. The serum IgG4 level was within normal range. Laparoscopic radical nephrectomy was performed and the postoperative pathological examination indicated a IgG4-RD. Cai et al. reported an 80-year-old IgG4 RD female patient noted as a CT-enhanced renal mass located on the inferior portion of the left kidney. Retroperitoneoscopic left radical nephrectomy was performed after clinical diagnosis of renal cell carcinoma. However, the interpretation of histological and immunohistochemical findings suggested IgG4related inflammatory pseudotumor. Serum IgG4 level was normal 2 weeks after surgery and the patient did not receive additional treatment.
Clinically, IgG4-related disease involved multiple organs were more common. It was , reported that more than 90% IgG4-related disease simultaneously involved organs including kidney, pancreas, or salivary gland lesions. Kawano et al. reported 41 IgG4-related disease involving the kidney, while 39 (95.1%) of them were complicated by other organ diseases. In the present case, an isolated mass was found in the renal parenchyma. Such lesion posed a diagnostic challenge, as it may mimic renal malignant tumors, especially there was no other organ involved. We generally differentiated IgG4-RD with isolated mass lesion based on history, radiological imaging, IgG4 level, and pathological results. Evidence of other organs with related diseases is helpful for diagnosis. Elevated serum IgG4 is also helpful for the diagnosis and is related to the severity of the disease. The imaging findings of IgG4-RDs are nonspecific and mostly present as multiple low-density nodules by CT scan in one or both kidneys. The T2-weighted MRI scans of the lesions are typically hypointense. The laboratory findings including urine test and serum IgG4 levels were within normal range in our present case. Therefore, the patient underwent unnecessary nephrectomy.
Glucocorticoid treatment is effective for most IgG4-RD patients. In this case, nephrectomy was performed because radiological findings strongly suggested the lesion a malignant tumor. Postoperative glucocorticoid therapy was not applied as the patient had no additional clinical symptoms and the serum IgG4 level was normal. Over 10 months after surgery, the patient had no uncomfortable symptoms.
In conclusion, we present a rare case of IgG4related inflammatory pseudotumor of the kidney that mimics renal carcinoma. Diagnosis is difficult if solitary renal mass in single organ involved. IgG4-RD should be considered as a differential diagnosis and percutaneous biopsy is recommended to avoid unnecessary surgery.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]