Bilateral thickening of the pericapsular renal area in a patient with refractory oedema of the legs

Clara Rajemiarimoelisoa, Nicolas Quirin, Fréderic Thony, Nicole Pinel, Hubert Mann and Daniel J. Cordonnier

Centre Hospitalier Universitaire, Grenoble, France

Correspondence and offprint requests to: Professor D J Cordonnier, Service de Nephrologie, Centre Hospitalier Universitaire de Grenoble, BP 217, 38043 Grenoble Cedex 09, France.

A 77-year-old man was admitted in June 1997 with refractory oedema of both lower limbs and moderate chronic renal insufficiency. He had been treated for hypertension for 30 years. In addition he had had a thyroidectomy for goiter with intrathoracic expansion (1972), prostatic endoscopic resection (1979), Parkinson's disease since 1979, cardiac insufficiency partially stabilized since 1985, repair of a hernia of the abdominal white line (1988) and constrictive pericarditis in 1988 (at microscopic level: fibrosis and non-specific chronic inflammation). The patient had not received any drugs known to induce fibrosis.

Clinical examination was unremarkable except lower limbs oedema. Investigations showed serum creatinine concentration 145 µmol/l (45–115), sodium 144 mmol/l (13–145), potassium 3.7 mmol/l (3.5–5.0), calcium 2.24 mmol/l (2.10–2.65), phosphorus 1.09 mmol/l (0.80–1.45), cholesterol 6 mmol/l (4.6–6.4), triglycerides 1.38 mmol/l (0.6–1.6), serum protein electrophoresis normal, immunoglobulin A 2.73 g/l (1–2.60), serum cryoglobulin 0, anti-nuclear cytoplasm antibodies 0, anti-tissue antibody 0, global anti- nucleus antibodies 1/100, prostate specific antigen 4.5 ng/ml (less than 2.0), parathormone level 127.4 pg/ ml (less than 4.5), creatinine clearance 41 ml/min, proteinuria 0.160 g/24 h, urinary sodium 162 mmol/24 h, urinary potassium 72.6 mmol/24 h, glycosuria 0.76 mmol/24 h, urinary urea 27.2 mmol/24 h.

Imaging was carried out to look for venous or lymphatic obstruction. Computed tomographic images in the axial plane showed tissue of intermediate density within the low density of the perirenal fat extending to the renal hilum. Periaortic and pericaval regions were not involved by this process. There was no evidence of pyelo-ureteric obstruction (Figure 1Go).



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Fig. 1. Unenhanced CT scan. The perirenal space is heterogeneous, with mixed fat and soft density tissues.

 
Magnetic resonnance imaging (MRI) examination was obtained. T1 weighted images in the coronal plane demonstrated the presence of a non-fatty tissue in the perirenal space. This tissue was of low signal on images before opacification (Figure 2Go). After intravenous injection of 10 ml of Gadolinium the signal of this tissue remained almost the same whereas some areas presented with a signal enhancement. This tissue had also a low signal on T 2-weighted images (Figure 3Go).



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Fig. 2. MRI at 1.5 T.T1-weighted (TR 450, TE 12) images in coronal plane. Before Gadolinium enhancement. Tissue of low signal intensity is seen within the high intensity signal of perirenal fat.

 


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Fig. 3. After Gadolinium enhancement. The signal of the kidney and the perirenal space is enhanced except for a band of tissue surrounding the perirenal space.

 
A percutaneous kidney and pericapsular area biopsy under scanning control was performed (Figure 4Go). By light microscopy, the kidney showed interstitial fibrosis and glomerular ischaemia (Figure 6Go). The pericapsular area was composed of a mixture of adipose tissue and diffuse fibrosis (Figures 5, 7 and 8GoGoGo). Electron microscopy showed that the pericapsular tissue exhibited mature active fibroblasts and numerous histiocytes with membrane bound lipidic inclusions; no mononuclear inflammatory cells were found. Extracellular matrix contained collagen fibrils (not shown). Immunofluorescence was not performed.



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Fig. 4. Enlargement of MRI picture number 2. The white box corresponds to the approximative site of the renal biopsy.

 


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Fig. 6. Cortical renal area. Interstitial fibrosis is seen (Goldner's trichrome, x10).

 


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Fig. 5. Pericapsular and renal specimens (Goldner's trichrome, x2).

 


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Fig. 7. Pericapsular area with dense fibrous tissue (Goldner's trichrome, x10).

 


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Fig. 8. Pericapsular area: fibroblasts contain lipidic inclusions (Oil red O, x20).

 
Neither lymphoma nor carcinoma was seen. The 1988 pericarditis specimens were reviewed and confirmed chronic non-specific inflammation.

The patient was managed conservatively. Eighteen months later, in spite of persisting oedema of the lower limbs and diuretic resistance, only slight modifications of the renal function were observed (serum creatinine level: 158 µmol/l; creatinine clearance: 30 ml/mn). A second MRI was performed and did not show any change.

Discussion

We have not found a cause of this perirenal fibrosis nor the actual cause of renal insufficiency but this case allowed us to bring out radio-pathological correlations. Detecting perirenal fibrosis by MRI is very rare [1]. To our knowledge only one case has been reported [2]. Its localization was bilateral as in our patient; by contrast, in the case of Yancey and colleagues there was some retroperitoneal involvement and no pathological diagnosis. Imaging findings in perirenal lymphoma include localized or diffuse occupation of the perirenal space with confluent retroperitoneal mass [3].

References

  1. Bechtold RE, Dyer RB, Zagoria RJ, Chen MYM. The perirenal space: relationship of pathologic processes to normal retroperitoneal anatomy. Radiographics 1996; 16: 841–854[Abstract]
  2. Yancey JM, Kaude JV. Diagnosis of perirenal fibrosis by MR imaging. J Comput Assist Tomogr 1988; 12: 335–337[ISI][Medline]
  3. Nguyen-Tan T, Servois V, Salomon AV, Neuenschwander S. Lymphome renal. (Cas no 3). J Radiol 1997; 78 [Suppl 12]: 10–12[ISI]