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| CASE REPORT |
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| Year : 2018 | Volume
: 6
| Issue : 2 | Page : 247-250 |
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Renal cell carcinoma and xanthogranulomatous pyelonephritis: A diagnostic challenge
Mohammed Khalidur Rahman1, Safia Rana2, Zeeba S Jairajpuri2, Shaan Khetrapal2
1 Department of Surgery, Lions Kidney Hospital and Research Institute, New Delhi, India
2 Department of Pathology, HIMSR, New Delhi, India
| Date of Web Publication | 27-Dec-2018 |
Correspondence Address:
Dr. Safia Rana
Department of Pathology, Hamdard Institute of Medical Sciences and Research, Jamia Hamdard, New Delhi - 110 062
India
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/amhs.amhs_66_18
The presenting symptoms of RCC (renal cell carcinoma) overlap closely with those of XGP (Xanthogranulomatous pyelonephritis) and can clinically as well as pathologically be confused with XGP which is an unusual inflammatory disorder. Most of the patients present with varied symptoms from the constellation of flank pain, fever, malaise, weight loss, and hematuria. We hereby report here a case of 52 year old male who presented with right flank pain, diagnosed erroneously as XGP on preoperative CT guided biopsy from the renal mass, on two occasions which eventually turned out to be clear cell variant of renal cell carcinoma. Right radical nephrectomy was done where the final histopathological diagnosis was of clear cell variant of RCC.
Keywords: Clear, renal cell carcinoma, xanthogranulomatous
How to cite this article:
Rahman MK, Rana S, Jairajpuri ZS, Khetrapal S. Renal cell carcinoma and xanthogranulomatous pyelonephritis: A diagnostic challenge. Arch Med Health Sci 2018;6:247-50 |
How to cite this URL:
Rahman MK, Rana S, Jairajpuri ZS, Khetrapal S. Renal cell carcinoma and xanthogranulomatous pyelonephritis: A diagnostic challenge. Arch Med Health Sci [serial online] 2018 [cited 2023 Mar 29];6:247-50. Available from: https://www.amhsjournal.org/text.asp?2018/6/2/247/248669 |
| Introduction | |  |
Xanthogranulomatous pyelonephritis is a rare variant of chronic destructive pyelonephritis and to distinguish it from a renal cell carcinoma (RCC) preoperatively, is often a diagnostic challenge. In clinical practice, therefore false diagnoses are frequent.[1]
Xanthogranulomatous pyelonephritis (XGP) is an atypical form of chronic pyelonephritis characterized by the destruction of the renal parenchyma and replacement with a chronic inflammatory infiltrate of lipid-laden macrophages, known as xanthoma cells.[2],[3]
Clear cell RCC can also be puzzling on microscopy as the clear cells may be misconstrued as infiltrating of foamy histiocytes that is usually the predominant element in XGP. Most of the patients present with varied symptoms from the constellation of flank pain, fever, malaise, weight loss, and hematuria. We report here a case of 52-year-old male who presented with right flank pain. Imaging showed an irregularly marginated lobulated mass lesion, originating from the lower pole of the right kidney. It was twice erroneously diagnosed with XGP, on preoperative computerized tomography (CT)-guided biopsy from the renal mass. Subsequently, it was proved to be clear cell variant of RCC. Right radical nephrectomy was performed given tentative diagnosis of RCC, and the final histopathological diagnosis was clear cell variant of RCC. This case report emphasizes the fact that imaging and clinical overlaps in the diagnosis, assessment, and management of this entity may occur.
| Case Report | | |
A 52-year-old male patient presented in the surgical outpatient department with complaints of right renal colic for the past 4 days. No history of fever or hematuria was present. The patient was a known diabetic for the past 7 years and was on medication. He was on irregular treatment for hypertension. Hematological investigations showed a total leukocyte count, i.e., 8.2 × 109/L with a normal differential count. Erythrocyte sedimentation rate was 20 mm/h. Biochemical investigations revealed blood urea of 37.2 mg/dL, serum uric acid of 7.2 mg/dL, and a raised serum creatinine of 1.35 mg/dL. The serum electrolyte done revealed the following: sodium 150 mmol/L, potassium 4.3 mmol/L, calcium 8.7 mg/dL, and inorganic phosphorus 4.6 mg/dL. Urine for culture and sensitivity was sterile; no pathogenic organism growth was seen after 48 h of incubation. Routine microscopic examination of urine was also within normal limits. Cytological screening of urine sample was done consecutively for 3 days which did not yield any atypical or malignant cell.
Ultrasound of the whole abdomen revealed a right kidney of normal size and echotexture. However, a rounded hypoechoic lesion was seen arising from the lower pole measuring 32.4 × 28.4 mm, suggestive of a mass lesion [Figure 1]. A contrast-enhanced CT (CECT) was advised to further rule out right renal mass lesion. CECT kidney ureters and bladder with CT urogram showed a well-defined, irregularly marginated, lobulated mass lesion approximately 40 mm × 33 mm in size, originating exophytically from the lower pole of the right kidney. On injection of contrast, a heterogeneous enhancement was evident [Figure 2]. The adjacent renal cortex was involved, and the lesion was seen compressing and invading the right upper ureter around pelviureteric junction causing abrupt ureteric narrowing and proximal hydroureteronephrosis. The uptake of contrast was normal. However, excretion into the ureter was slightly delayed. The renal artery and veins were normal. | Figure 1: Ultrasonogram of right kidney showing rounded hypoechoic lesion arising from its lower pole
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 | Figure 2: Computerized tomography scan showing well defined irregularly marginated lobulated mass lesion originating from the lower pole of right kidney
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Since the presenting lesion was <4 cm, a CT-guided biopsy was done from the right renal mass. Multiple cores, aggregating to 6 mm were taken out and sent for histopathological evaluation. The microscopic examination showed mostly necrotic tissue and few large polygonal cells with granular cytoplasm. Immunohistochemistry (IHC) for cytokeratin was negative in these large cells [Figure 3]. Other IHC markers could not be done due to financial constraints. | Figure 3: Microphotograph showing xanthogranulomatous change, few large polygonal cells with granular cytoplasm in the first computerized tomography guided biopsy (H and E, ×40)
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A diagnosis of xanthogranulomatous inflammation was made though, the radiological picture did not correlate with histological findings, and therefore, the patient was subjected to another tru-cut biopsy which revealed 10 glomeruli with progressive sclerosis, marked tubular atrophy, interstitial fibrosis, and heavy mononuclear inflammation. However, no tumor area was identified [Figure 4]. A histological diagnosis of chronic interstitial nephritis was made, suggestive of a benign inflammatory etiology. | Figure 4: Sections from second tru-cut biopsy showing sclerosis, tubular atrophy, interstitial fibrosis, and heavy mononuclear inflammation suggesting chronic interstitial nephritis (H and E, ×40)
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The patient was planned for a radical nephrectomy since the radiological features were more in favor of a malignant neoplasm as evident on CECT and ultrasonography (USG). Postoperatively, the specimen was sent for histopathological evaluation. Grossly, the specimen measured 5.5 cm × 4.8 cm × 0.5 cm. Tumor was seen extending into the perinephric tissue and renal sinuses. On microscopy, a clear cell carcinoma was seen extending into perinephric tissue, beyond renal capsule and also in the renal sinus but not beyond Gerota's fascia. Furman's nuclear grade of G3 was made since nuclei were very irregular, approximately 20 μ with large and prominent nucleoli [Figure 5]. A single hilar lymph node was seen involved by the tumor. Lymphovascular invasion was present. Renal veins and ureteric margins were free of tumor. The final pathological stage of pT3aN1 M 0 was given in the histopathology report. | Figure 5: Section from tumor showing clear cells with irregular nuclei, large and prominent nucleoli (H and E, ×40)
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| Discussion | | |
XGPN has been described as a great imitator or a masquerading tumor in adults and pediatric age groups XGP is an uncommon form of chronic pyelonephritis due to from chronic obstruction usually from renal stones and also the formation of an inflammatory mass causing the destruction of renal parenchyma, mimicking malignancy.[4]
Preoperative diagnosis of focal XGP is difficult because of radiological similarities to RCC. High index of suspicion on various imaging modalities and biopsy is important in distinguishing the two entities.[4] Our case was more difficult to diagnose because clinically patient did not show signs of inflammation and had no history of urinary tract infection or stones.[5] Histologically, the kidney also revealed changes of XGP which can be confused clinically, grossly, and microscopically with RCC and both features were coexistent.[6] The coexistence of xanthogranulomatous pyelonephritis and RCC is extremely rare.[1]
Previous literature has reported a case where USG, CT, magnetic resonance imaging, and renal angiography revealed a cystic renal tumor in the upper pole of the left kidney invading the spleen, and paraaortic lymph node swelling. Left radical nephrectomy combined with splenectomy and partial diaphragmectomy was performed under a tentative diagnosis of RCC. However, histopathological findings revealed xanthogranulomatous pyelonephritis (XGP).[5]
The diagnostic accuracy of percutaneous core biopsy is improved when extensive sampling of the tumor is performed, i.e., at least three representative core biopsies are taken, with an overall sensitivity of 100% for differentiating malignant from benign tumors.[7] Looking at clear cell RCC versus histology that is not a clear cell type, the overall accuracy is in the order of 93%. Currently, the role of preoperative biopsies for pathological diagnosis and treatment planning is being renewed. The rationale behind most of the studies is to guide clinical decision-making, including avoidance of surgery for benign tumors, management of small renal masses (SRMs), and patient selection for surgery in high-risk populations. As the specificity of fine-needle aspiration, even in experienced hands, is low compared with histology, percutaneous core biopsy is now the most common approach. However, sampling issues such as the availability of tumor cells and limited architectural information have raised some concerns about their use and the potential of histological misdiagnosis.[8] Several recent studies demonstrated that a substantial proportion of SRMs are benign and the rate of malignancy increases with the tumor size.[9],[10]
| Conclusion | | |
This case report highlights the importance of keeping XGPN as a differential diagnosis of a renal mass. Preoperative diagnosis of focal XGP is difficult because of clinical and radiological similarities to RCC, especially when signs of inflammation are few and no associated history of urinary tract infection or stones. Renal biopsy has found recent acceptance in selected clinical situations and is now being increasingly used for the evaluation of SRM <4 cm in diameter.
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.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
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