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A Rare Case of Primitive Neuroectodermal Tumour (Pnet) of Kidney with Review of Literature

Narendra Kumar, Deepak Das, Vijai Simha, Vani Bharani, Uttam Kumar Mete

Narendra Kumar, Additional Professor, Department of radiotherapy Postgraduate; Department of Medical Education and Research (PGIMER) Chandigarh, Sector 12, 160012, Chandigarh, India
Deepak Das, Department of radiotherapy PGIMER Chandigarh, Sector 12, 160012, Chandigarh, India
Vijai Simha, Senior Registrar , Department of radiotherapy, PGIMER Chandigarh, Sector 12, 160012, Chandigarh, India
Vani Bharani, Senior Registrar, Department of Pathology, PGIMER Chandigarh, Sector 12, 160012 Chandigarh, India
Uttam Kumar Mete, Professor, Department of Urology, PGIMER Chandigarh, Sector 12, 160012, Chandigarh, India

Correspondence to: Narendra Kumar, Additional Professor, Department of radiotherapy Postgraduate Department of Medical Education and Research (PGIMER) Chandigarh, Sector 12, 160012, Chandigarh, India.
Email: drnarendra74@gmail.com
Telephone: +91-172-2756280
Received: March 8, 2016
Revised: April 28, 2016
Accepted: May 3, 2016
Published online: June 29, 2016

ABSTRACT

We report a case of primitive neuroectodermal tumour of the kidney in a middle aged male who presented as a large left sided renal mass similar to renal cell carcinoma. A cytoreductive nephrectome was done which showed primitive neuroectodermal tumour in the left kidney. A Positron Emission Tomography CT scan was done which showed metastasis in the lung and para-aortic lymph nodes. We describe the natural history, clinical and pathological features and management strategy of this rare variety of tumour.

Key words: Primitive Neurectodermal Tumour; PNET; Cytoreductive Nephrectomy; Ewings sarcoma family of tumours

© 2016 The Authors. Published by ACT Publishing Group Ltd.

Kumar N, Das D, Simha V, Bharani V, Mete UK. A Rare Case of Primitive Neuroectodermal Tumour (Pnet) of Kidney with Review of Literature. Journal of Tumor 2015; 4(3): 445-447 Available from: URL: http: //www. ghrnet. org/index. php/jt/article/view/1634

Introduction

Primitive neuroectodermal tumour (PNET) is presumed to be of neural crest origin, mostly presenting as bone or soft tissue masses. It usually occurs in children and young adults. PNET occurs rarely as primary renal neoplasm and exhibits highly aggressive biological behaviour. We report a case of a 54 year old male who presented with mass in the left side of abdomen. On computerised tomography (CT), he was found to have a large left renal mass. He underwent cytoreductive nephrectomy where the pathology report showed PNET of the kidney.Positron emission tomography (PET) CT done was suggestive of malignant left renal mass with metastasis to right lung and paraaortic lymph nodes.

CASE REPORT

A 54 year old male came to the radiotherapy OPD August 2015 with the complaint of swelling in left side of abdomen for 3 months which was gradually progressive in size. He had no other associated symptoms. On per abdominal examination, he was found to have arround 10×10 cm mass occupying most of left side of the abdomen which was firm, fixed and nontender.

A CT of the abdomen demonstrated a heterogenous mass lesion measuring 12 × 10.5 × 18.4 cm with enhancing solid component and non enhancing cystic component arising from left kidney involving mid and lower pole and part of upper pole. There was loss of fat plane between mass and left psoas muscle. Left renal vein was normal. Right kidney showed few cysts largest of size 3.8 × 3.3 cm. There was few small lymph nodes seen in paraaortic region and along renal vessels. There was no free fluid in peritoneal cavity and bilateral lung fields were normal.

PET-CT demonstrated intense2-[18F]flouro-2-deoxy-glucose (FDG) uptake (standardised uptake value[SUV] maximum 11.8) in the large heterogeneously enhancing soft tissue mass lesion measuring 13.5 × 11.5 × 20.6 cm involving the left kidney. The fat planes with the left psoas muscle were lost and the lesion was seen to infiltrate into the muscle. Intense FDG uptake (SUV maximum 7.5) was noted in two enlarged pleural based nodular lesions in upper lobe and middle lobe of right lung measuring 2 × 1.4 cm. Intense FDG uptake (SUV maximum 8.5) was noted in right lower paratracheal, AP window, subcarinal and bilateral hilar lymph nodes. Mild FDG uptake was noted in a few enlarged paraaortic and aortocaval lymph nodes. These features were suggested of primary left renal lesion with metastatic right lung lesions and paraaortic lymph nodes.

Then the patient underwent cytoreductive nephrectomy. Grossly the mass had a size of 19 × 13 × 12 cm. Capsule was intact with no areas of haemorrhage or necrosis. The cut surface showed a tumour mass, almost occupying whole of the renal parenchyma measuring 17 × 11 × 9 cm. It was tan-brown to tan-red in colour with large areas of necrosis and haemorrhage. Renal sinus could not be delineated.

Microscopically tumour arranged in nests and forming sheets.The tumour cells were round to oval with fine nuclear chromatin, occasional nucleoli and scanty to moderate cytoplasm. Frequent mitosis and large areas of necrosis were seen. On immunohistochemestry, tumour cell show strong positivity for vimentin, membranous positivity for cluster of differentiation (CD) 99 and cyptoplasmic positivity for neuron specific enolase (NSE). Immunostain for epithelial membrane antigen (EMA) and CD34 was negative. Perinephric fat was involved by tumour. Ureteric and vascular resection limit were free of tumour.

The patient was subsequently begun on systemic chemotherapy with 6 cycles of chemotherapy with cisplatin (30 mg/m2) and etoposide (100 mg/m2). Patient was reassessed with CT scan at the end of three cycles of chemotherapy on which showed partial response. The patient is presently asymptomatic and is on planned for further chemotherapy and palliative radiotherapy.

Discussion

Primitive neuroectodermaltumor is a malignant neoplasm of neural crest origin. It was first described by Arthur Pourdy Stout in 1918, where it occurred in the ulnar nerve. It belong to the Ewing sarcoma family of tumours and is one of the small blue round cell tumours. It is a very rare tumour representing about 1% of all sarcomas. It can occur in the trunk, extremities, brain, spinal cord and sympathetic nervous system as well as peripheral tissues, paraspinal region, and less commonly, genitourinary tract[1]. Renal PNET was first described by Seemayar et al[2,3].

Renal PNET usually occurs in children and young adults. The peak age at diagnosis of PNET in general is 10-15 years of age. Average age at diagnosis of renal PNET as seen in the literature has been 27.8 years, ranging from 4 to 62 years. In our patient the age at presentation was 54 years which is not the usual age at which PNET of the kidney can be suspected; rather it is closer to the median age of presentation of renal cell carcinoma which is 64 yrs. There is a slight male predominance seen in the literature for PNET in general as well as renal PNET. The tumours tend to be very large and maximum diameter of renal PNET is more than 10 cm (average 12.4 cm) with size ranging from 4 to 24 cm[4,5]. This difference in size may be a differentiating feature from renal carcinoma as the tumours of renal cell carcinoma can be smaller than 3cm and can be multi-focal in the setting of Von hippel Lindau syndrome. Multifocality is a feature that has never been described in PNET of the kidney.

The presenting symptoms of renal PNET are nonspecific and similar to other renal tumours[4]. Pain, palpable mass and hematuria are the most common symptoms[5]. Imaging of renal PNET often reveals large mass with large areas of haemorrhage and necrosis partially or completely replacing kidney. The mass often has multiple septum like structures. The haemorrhage is diffuse or central in case of PNET but it is central in case of renal cell carcinoma[6]. In several case series, tumour extension has been shown to cause thrombosis of the renal veins as well as the inferior venacava upto the right atrium[7].

To summarize, there is no single feature except a younger age at presentation which can lead to a preoperative suspicion of a PNET in a patient presenting as a renal mass (even this was not present in the index patient). The diagnosis of renal PNET is usually made postoperatively, based on morphology, immunohistochemical and cytogenetic analyses. Grossly, renal PNET looks greyish white with areas of necrosisand haemorrhage due to rapid tumour growth. Viable tumour is often found preserved around the blood vessels. Microscopically, the picture is that of a primitive, undifferentiated neoplasm. On hematoxylin and eosin-stained sections, there are monotonous sheets of small round blue cells with hyperchromatic nuclei and scant cytoplasm. The histological hallmark is formation of Homer-Wright rosettes or perivascular pseudorosettes involving small round hyperchromatic cells. Immunohistochemically the tumour cells are strongly positive for CD99 and Friend Leukemia Virus Integration (FLI)-1.Virtually all cases express one of several different reciprocal translocations, most of which involve breakpoints that are clustered within a single gene locus designated the EWSR1 gene on chromosome 22q12. In 85 to 90% cases of Ewings family tumours, a recurrent chromosomal translocation, t (11; 22) (q24; q12), fuses the 5' portion of the EWSR1 gene on chromosome 22 to the 3' portion of the FLI1 (friend leukemia integration locus-1) gene on chromosome 11wich can be detected by flouresceneinsitu hybridization. Using a large panel of immunohistochemical markers is often essential [cytokeratin, EMA, WT1 (Wilms tumour 1), synaptophysin, muscle specific actin, desmin, myogenin, leukocyte common antigen (LCA) and CD45] to exclude other round cell tumours because of their important similarities[1-6,8-14]. Differential diagnosis of renal PNET includes wilms tumour, neuroblastoma, clear cell carcinoma, lymphoma, rhabdomyosarcoma, small cell variant of osteosarcoma and small cell anaplastic neuroendocrine carcinoma.

Renal PNET is a highly aggressive tumour with high metastatic potential and almost 50% of patient present with distant metastases, most commonlyto regional lymph nodes, lungs liver and bones[1-3,11,12]. Prognostic factors are tumour stage, grade, patient’s age, extent of surgery, surgical margin status and treatment beginning time[2,11]. The 5-year disease-free survival rate is 45% to 55% and median relapse free survival is 2 years in patients with metastatic disease[1,9].

There are no standard guidelines for the treatment of renal PNET[11]. The primary treatment is surgery followed by chemotherapy[12]. Cisplatin based multi-agent chemotherapy can be considered the standard of care. PNET has shown sensitivity to chemotherapy regimens containing drugs- vincristine, adriamycin, ifosfamide, etoposide, cisplatin[11]. The index patient had partial response to cisplatin etoposide doublet chemotherapy. Additional multi-agent chemotherapy has not been shown to be effective in the setting of metastatic ewingfamily of tumours.

COMPETING INTERESTS

There are no conflicts of interest with regard to the present study.

REFERENCES

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Peer reviewer: Katsuyuki Aozasa, MD, PhD, Emeritus Professor, 1-37-16 Niwashirodai, Sakai, Osaka, Japan; Gulhane Research and Training Hospital, Department of Urology, Istanbul, Turkey.

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