Primary Ewing's sarcoma/primitive neuroectodermal tumor of the kidney: a clinicopathologic and immunohistochemical analysis of 11 cases

Primary Ewing sarcoma of the kidney mimicking cystic papillary renal cell carcinoma in an older patient: A case report

BACKGROUND

Ewing's sarcoma (ES) is a neuroectodermal tumor that typically occurs in the bones and soft tissues of children and young adults. Primary renal ES is rare; only a few cases and a small case series have been documented, and only four cases involved primary renal ES in older people (> 65 years old).

CASE SUMMARY

Herein, we describe the radiological and pathological features of primary renal ES in an older person. A 76-year-old man complained of poor oral intake and was found to have a large cystic renal mass with indistinct margins on computed tomography. Ultrasound-guided biopsy revealed that the tumor contained small round blue cells. The patient underwent a right radical nephrectomy. The tumor cells showed diffuse membranous CD99, and nuclear friend leukemia integration 1 transcription factor and NK2 Homeobox 2. Fluorescence in situ hybridization revealed EWSR1 translocation. Postoperatively, 18F-fluorodeoxyglucose positron emission tomography revealed no evidence of metastasis. The patient was diagnosed with primary renal ES. Six months following the surgery, local recurrence and distant metastasis were observed. Primary renal ES is rare and often lethal in older individuals. The specific imaging findings are unknown, and treatment protocols have not been standardized.

CONCLUSION

This case report describes the radiological and pathological features of primary renal ES in an older person.

Primary peripheral neuroectodermal tumor or Ewing's sarcoma of the kidney: A rare case and review of the literature

Peripheral neuroectodermal tumors (PNET), or Ewing sarcoma, are tumors that generally develop in bone; extraskeletal locations are rare. Renal PNETs are rare and are characterized by an aggressive clinical course and a poor prognosis. We report the case of a young patient who presented with abdominal and lumbar pain with a palpable abdominal mass. The imaging was in favor of a huge renal tumor, and the histological analysis allowed the diagnosis of a renal PNET. The therapeutic attitude was multimodal, including surgery and chemotherapy, allowing complete remission and a favorable outcome.

Gastrointestinal Ewing Sarcoma: A Clinicopathological and Molecular Genetic Analysis of 25 Cases

Occurrence of extraskeletal Ewing sarcoma (ES) in the gastrointestinal (GI) tract is extremely rare. Here, we report 25 cases of ES arising primarily in the GI tract with a focus on the clinicopathological and molecular features, differential diagnosis, and biological behavior. Thirteen patients (52%) were male, and 12 (48%) were female with age ranging from 9 to 59 years (mean: 36.2 years; median: 38 years). Twenty-one tumors (84%) occurred in the small intestine, 3 (12%) in the stomach, and 1 (4%) in the anal canal. At operation, 8/18 (44.4%) patients presented with abdominopelvic disseminated disease. Tumor size measured from 2 to 25 cm (mean: 8.2 cm; median: 6 cm) in maximum size. Microscopically, the tumors were composed of infiltrative small round, ovoid, or short spindle cells arranged mostly in lobular and solid sheet-like patterns with a rich capillary vasculature. Focal formation of Homer Wright-type rosettes and pseudoalveolar architecture was noted each in 2 (8%) cases and 3 (12%) cases. Besides CD99 (25/25; 100%), Fli-1 (15/15, 100%), and NKX2.2 (14/16; 87.5%), the tumor cells also showed variable staining of CD117 (14/17; 82.4%). Of 25 cases, 23 (92%) demonstrated EWSR1 rearrangement by fluorescence in situ hybridization analysis. The 2 cases with negative fluorescence in situ hybridization results were found to harbor EWSR1::ERG and EWSR1::FLI1 fusion by further RNA sequencing, respectively, with a median follow-up of 12 months (range: 1 to 42 months), 5/19 (26.3%) patients developed visceral metastasis and 12/19 (63.2%) patients died of the disease (range:1 to 33 months; median: 9 months). This study showed that GI ES had a predilection for the small intestine, although other sites of the GI tract could also be involved. GI ES had a poor prognosis with a high rate of mortality, particularly in patients with abdominopelvic disseminated disease. In light of appropriate therapeutic strategies and prognostic considerations, it is essential not to misdiagnose GI ES as gastrointestinal stromal tumor owing to the expression of aberrant CD117.

An Incidental Diagnosis of Extraosseous Ewing's Sarcoma in the Kidney

Ewing's sarcoma is generally observed in the skeletal and connective tissues of paediatric individuals. The occurrence of extraosseous neuroectodermal tumours is uncommon. Renal Ewing's sarcoma usually presents with flank pain, haematuria, or as an abdominal mass. Immunohistochemistry and fluorescence in situ hybridization (FISH) techniques are essential in its diagnosis and differentiation from other tumours. We present asymptomatic renal Ewing's sarcoma in a 19-year-old female patient who was diagnosed incidentally, and the CT scan confirmed a 2.8 cm left mid-pole renal mass suggestive of malignancy. She was managed with a robotic partial nephrectomy. Tumour immunohistochemistry and the FISH technique confirmed the diagnosis of Ewing's sarcoma. The patient made an uneventful recovery and was referred for chemotherapy. This case report illustrates that despite the aggressiveness of the tumour, it can be detected earlier despite an asymptomatic presentation and be successfully treated with nephron-sparing surgery and chemotherapy.

Primary Ewing’s sarcoma of the kidney: a rare masquerader of renal cell carcinoma on imaging

Background

The Ewing sarcoma family of tumors comprises a group of high-grade small round cell tumors, including Ewing sarcoma of bone, extra-skeletal Ewing sarcoma, peripheral primitive neuro-ectodermal tumor (PNET), and Askin tumor (thoraco-pulmonary PNET). They are more prevalent in young children and adolescents. Ewing's Sarcoma is an aggressive tumor majorly described in bones. Primary renal Ewing's sarcoma is an extremely rare entity, characterized by a very aggressive course, with very few reported cases in the literature.

Case presentation

We present an 18-year-old girl who presented with sudden onset left flank pain and hematuria. The patient had histopathology-proven primary renal Ewing's sarcoma, which was initially misdiagnosed as renal cell carcinoma on imaging.

Conclusions

Owing to its non-specific radiological appearance, a high index of suspicion and a systematic approach is essential for detection of renal Ewing’s Sarcoma.

Renal Primitive Neuroectodermal Tumor Mimicking Wilms' Tumor in a Young Boy: A Case Report of a Rare Entity with Review of the Literature

Primary renal primitive neuroectodermal tumors (PNET) are an extremely rare entity. The tumor is very aggressive presenting with metastasis and carries a dismal prognosis. We describe the case of renal PNET in an 11-year-old boy with a solid cystic lesion in the right kidney with a thrombus in the inferior vena cava and lung nodules, mimicking Wilms' tumor.

Renal primitive neuroectodermal tumor. The first case series from Syria

Primitive neuroectodermal tumor (PNET) mainly arises from soft tissues of the extremities such as humerus, femur, C tibia. It rarely arises from kidney; less than 200 cases have been reported in the literature. The clinical presentation and radiography findings are not specific. Here we first report two cases of renal primitive neuroectodermal tumor in Syria.

the first patient was 26-year-old- female that presented to urology clinic complaining of right flank pain. Ultrasonography of the abdomen showed a large mixed heterogeneous mass in the right kidney with no hemorrhage or calcification and MSCT of abdomen and pelvis demonstrate a mixed well-demarcated heterogeneous mass measuring (74*117) mm in the right kidney right radical nephrectomy was performed.

The second patient 19-year-old-male presented with left flank pain. Ultrasonography of the abdomen showed mixed large mass involving the left kidney, with unmarked border. The CT of the abdomen and pelvis demonstrating a (30*110*90) mm left renal mass and periaortic lymphadenopathy measuring (45*28) mm. The patient underwent Left radical nephrectomy with periaortic lymphadenectomy dissection. The final diagnosis for both cases was Renal PNET based on microscopic and immunohistochemistry examination.

In patient with suspected renal mass in the radiographic images, the diagnosis of renal primitive neuroectodermal tumor should be kept in the mind despite its rarity. The final diagnosis is done by histopathological study in association with immunohistochemical examination.

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Here we will first report two cases of renal PNET in Syria.

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The diagnosis of renal primitive neuroectodermal tumor should be kept in the mind despite its rarity.

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The final diagnosis is done by histopathological study in association with immunohistochemical examination.

Adult Wilms Tumor: Genetic Evidence of Origin of a Subset of Cases From Metanephric Adenoma

The genetics of nephroblastoma (Wilms tumor) occurring in adults is largely unknown, as studies have largely been limited to isolated case reports. We, therefore, studied 14 adult Wilms tumors for genetic alterations, using expanded targeted sequencing on 11 cases. The patients ranged from 17 to 46 years of age (mean and median, 31 y), and there were 8 males and 6 females. Five Wilms tumors harbored BRAF V600E mutations. All of these had better-differentiated areas identical to metanephric adenoma, as has previously been described. In 3 such cases, microdissection studies revealed that the BRAF V600E mutation was present in both the metanephric adenoma and Wilms tumor areas; however, additional genetic alterations (including TERT promoter mutations in 2 cases, ASLX1/ATR mutations in 1 other case) were limited to the Wilms tumor component. These findings suggest that the Wilms tumor developed from the metanephric adenoma. Other adult Wilms tumors harbored genetic alterations previously reported in the more common pediatric Wilms tumors, including WT1 mutations (2 cases), ASLX1 mutations (3 additional cases), NSD2 mutation (1 additional case), and 11p loss (3 cases). In summary, a significant subset of adult Wilms tumors (specifically those of epithelial type with differentiated areas) harbor targetable BRAF V600E mutations and appear to arise from metanephric adenomas as a consequence of additional acquired genetic alterations. Other adult Wilms tumors often harbor genetic alterations found in their more common pediatric counterparts, suggesting at least some similarities in their pathogenesis.

Primary Renal Sarcoma with SS18::POU5F1 Gene Fusion

We report the first case of a primary renal undifferentiated sarcoma harboring an SS18::POU5F1 gene fusion. The patient was a 38 year-old male diagnosed with a 5 cm renal tumor which invaded the adrenal gland and extended into the renal vein. Microscopically, the neoplasm had a predominantly undifferentiated round cell morphology, with areas of rhabdoid and spindle cell growth. Similar to the previously reported cases with this fusion, by immunohistochemistry the neoplasm expressed S100 protein and epithelial markers (diffuse EMA, focal cytokeratin), suggesting the possibility of a myoepithelial phenotype. This report documents another example of a fusion-positive undifferentiated soft tissue sarcoma occurring as a primary renal neoplasm, adding to the already broad list of such entities. It highlights the crucial role of molecular analysis in establishing a specific diagnosis given the overlapping morphology and immunophenotypes such entities may exhibit. This article is protected by copyright. All rights reserved.

Primary primitive neuroectodermal tumour of the kidney in adults: Experience of managing 12 cases with systematic review and pooled analysis of literature

INTRODUCTION

Primitive neuroectodermal tumor (PNET) of the kidney is unusual in adults. These tumours are diagnosed mainly on histopathology and that too sometimes has limitations. With this study, we aimed to review our clinical and histopathological data of patients with renal PNET and reviewing the world literature.

METHODS

In this retrospective study, we reviewed our database from January 2006 to July 2018 to include all the cases of primary PNET of the kidney. We also performed systematic literature search to identify all the relevant series on renal PNET.

RESULTS

A total of 12 patients including 5 men and 7 women were managed during the above mentioned period. Out of these 7 patients, 2 patients had metastasis at diagnosis, one had locally advanced disease, 6 underwent radical nephrectomy, 5 patients received adjuvant chemotherapy (two currently receiving) and only 1 patient received adjuvant radiotherapy (RT). On Immunohistochemistry (IHC), CD99 and FLI1 were positive in all the patients. Median survival was 10 months. In our review 10 studies were included, 38.6% of the patients had metastatic disease and 10.7% had locally advanced disease at diagnosis. Overall mean survival was 33.75 months. CD99 and FLI1 were positive in 94.3% and 78.5%, respectively.

CONCLUSION

PNET remains a pathological diagnosis and IHC has important place in diagnosis of PNET. Locally advanced and metastatic disease is common at diagnosis leading to overall poor survival.

Management of Abdominal Ewing's Sarcoma: A Single Institute Experience

Ewing’s sarcoma (ES)/primitive neuroectodermal tumors (PNETs) are a rare group of tumors commonly arising from bones, uncommonly from soft tissues, and rarely from abdomen. The aim of the study was to analyze the outcome (recurrence-free survival[RFS]), patient characteristics, role of FDG-PET (fluorodeoxyglucose positron emission tomography) computerized scan, chemotherapy and radiation, and prognostic factors. We retrospectively studied patients diagnosed with abdominal ES/PNET and treated surgically between June 2005 and November 2019. Ten patients were included in the study, with a median age of 36.5 years (19–46 years). The median follow-up was 25 months (3–178 months). The site of origin was the retroperitoneum, small bowel, and abdominal wall in six, two, and two patients, respectively. 70% of patients were treated with induction chemotherapy. R0 resection was achieved in 90% of patients. With chemotherapy, there was significant reduction in tumor size (p = 0.034) with non-significant reduction in SUV max (p = 0.31). The 1- and 2-year RFS were 88.90% and 76.20%, respectively. Pathological peritoneal metastasis and ability to achieve R0 resection were prognostic factors affecting RFS. These patients must be offered multimodality treatment. Induction chemotherapy significantly reduces the tumor size. Pathological peritoneal metastasis and ability to achieving R0 resection significantly affect survival.

Primitive neuroectodermal tumor of the pericardium: a case report and literature review

Background

The primitive neuroectodermal tumors (PNETs) are a family of highly malignant tumors with a multidirectional differential potential. The tumors are characterized by aggressive small round tumor cells that originate from the spinal cord of the central and sympathetic nervous systems. Cases involving the pericardium are extremely rare. Herein, we present a case of peripheral primitive neuroectodermal tumor (pPNET) that originated in the pericardium.

Case presentation

A 23-year-old woman presented with cough and progressive dyspnea for 1 month, followed by eyelid and facial edema for 10 days, without any apparent cause. Significantly elevated tumor markers were detected in her blood. A cardiac ultrasound revealed a 74 mm × 61 mm spherical mass that was attached to the left pericardium, as well as massive pericardial effusion. Positron emission tomography-CT (PET-CT) showed focal hypermetabolism in the left pericardium. Via histopathology and immunohistochemistry, the spherical mass was identified as PNETS. The patient was successfully treated with a combination of surgical resection via thoracotomy and postoperative chemotherapy, and she was disease-free for 7 years at follow-up. Unfortunately, at 7 years after the treatment, the patient’s pPNET recurred. Positron emission tomography-MRI (PET-MRI) and 64-slice coronary CTA revealed that the aorta and multiple coronary arteries were involved. Subsequently, the patient refused a heart transplant and voluntarily left the hospital.

Conclusions

This paper reports on a rare and recurrent case of PNET in the parietal pericardium. With respect to the different biologic characteristics and prognoses of pPNETs (compared to other known pericardium tumors), it is essential to consider this entity as a differential diagnosis in pericardium tumors.

Primary Ewing Sarcoma of Seminal Vesicle on PET/CT

ABSTRACT

Ewing sarcoma is an aggressive malignancy that most often presents as an undifferentiated primary bone tumor; less commonly, it arises in extraosseous soft tissues of mesenchymal cell origin. Primary extraosseous involvement of seminal vesicle is rarely reported. Herein, we describe FDG PET/CT and MRI findings of a 55-year-old man who presented with a pelvic mass, which was confirmed to be primary Ewing sarcoma/primitive neuroectodermal tumor arising from seminal vesicle by histopathologic findings.

Successful Radical Pneumonectomy for a Primitive Neuroendodermal Tumor in the Lung: A Case Report and Review of the Literature

Peripheral primitive neuroendodermal tumors (PNETs) and Ewing's sarcoma belong to the Ewing family of tumors and are small round-cell malignancies originating from spinal cord cells. These tumors account for 5% of all small round-cell malignant neoplasms. PNETs that arise from the lung parenchyma without pleural or chest wall involvement are very rare. We report a case of an adult female with a large pulmonary PNET who had given birth just 1 month prior to the diagnosis. She had cough and expectoration for 6 months, and the preoperative examination showed no metastases. Thus, we performed radical pneumonectomy and lymph node dissection. The patient recovered well without surgical complications and was discharged 7 days after the surgery. Postoperative pathology confirmed that the tumor was a small round-cell malignancy, and the tumor cells were positive for CD99, Friend leukemia virus integration 1 (FLI-1), and neuron-specific enolase (NSE), which was consistent with the diagnosis of a PNET. For primary large pulmonary PNETs, radical pneumonectomy may be a safe surgical method, worthy of further application in clinical practice.

Penis as a primary site of an extraskeletal Ewing sarcoma: A case report

RATIONALE

The Ewing sarcoma family of malignant tumors is a group of tumors characterized by morphologically similar round-cell neoplasms and by the presence of a common chromosomal translocation; Ewing sarcoma family of tumors typically occur in children and young adults between 4 to 15 years of age. The primary tumor usually originates in the bone, extraskeletal localization is rare.

PATIENT CONCERN

We present a case report concerning a 32-year-old male patient with a primary involvement of the penis.

DIAGNOSIS

The histopathology from the first penile biopsy showed a small-cell neuroendocrine carcinoma; however, that result was based on a sample obtained at a different facility than the Sarcoma Center, where the investigating pathologist did not have the adequate expertise. The patient then underwent a radical penectomy and a second reading of the histology was demanded after a radical penile amputation when Ewing sarcoma with R1 resection was confirmed.

INTERVENTIONS

The patient was referred to the national Sarcoma Center, where - using a multidisciplinary approach - the treatment was started with curative intent. However, it was preceded by a non-standard initiation of the therapy due to the poor primary diagnosis.

OUTCOMES

The non-standard therapy at the onset of the disease caused a poor prognosis of an otherwise curable diagnosis. Despite all that, the patient survived for a relatively long time.

LESSONS

The treatment of sarcomas with atypical localizations should be conducted by an experienced multidisciplinary team in a center with experience in sarcoma treatment.

Neuroendocrine differentiation in a large series of genetically-confirmed Ewing's sarcoma family tumor: Does it provide any diagnostic or prognostic information?

Given the potential for neuroendocrine differentiation in Ewing's sarcoma family of tumors (ESFT), we aimed to determine neuroendocrine expression in a large series of genetically-confirmed ESFT and its prognostic significance in clinically-localised neoplasms (n = 176). Slides prepared from tissue microarrays were stained for Insulinoma-associated protein 1 (INSM1), CD56, chromogranin-A and synaptophysin. INSM1 expression was present in 59% of ESFT, while synaptophysin, chromogranin-A and CD56 were expressed in only 13%, 8% and 5% of ESFT, respectively. Histological subtypes were only significantly correlated with INSM1 (p = 0.032) or CD56 (p = 0.016) immunoexpression. Regarding prognosis, no significant association was found between INSM1, synaptophysin or chromogranin-A immunoexpression and progression-free survival (PFS) or overall survival (OS). Despite the low proportion of tumors with CD56 immunoreactivity, CD56 expression was shown to correlate with both poor PFS (p < 0.001) and poor OS (p < 0.001) in the present series. In conclusion, neuroendocrine differentiation is often present in ESFT, and in the present study INSM1 expression in particular was found to be higher than previously described in Ewing's tumors. Nevertheless, this finding does not distinguish these tumors from other round cell tumors that may show focal or diffuse neuroendocrine differentiation. CD56 expression could be used as a prognostic factor in ESFT, although given the results herein obtained, we recommend a prospective validation in independent series including localized and disseminated tumors in ESFT.

Immunophenotypic Characterization of Germ Cell Tumor-Derived Primitive Neuroectodermal Tumors: Evidence for Frequent Neuronal and/or Glial Differentiation

CONTEXT.—

Primitive neuroectodermal tumors (PNETs) may arise as a somatic-type malignancy in germ cell tumors. In this setting, most PNETs resemble those of the central nervous system and lack chromosome 22 translocations. However, description of the morphologic and differentiation spectrum of PNETs arising from germ cell tumors is lacking.

OBJECTIVE.—

To investigate the morphologic and immunohistochemical features of these tumors, concentrating on neuronal and glial features.

DESIGN.—

We selected cases based on a morphologically identifiable glial and/or differentiated neuronal component in association with the undifferentiated PNET. Immunohistochemistry for glial fibrillary acidic protein, S100 protein, synaptophysin, chromogranin A, and SOX11 was performed on tumors with available material, with the scoring of both staining intensity (0-3) and extent (0-3). Thirteen qualifying PNETs of testicular origin with available immunohistochemical stains or stainable material were identified. The complete stain panel was performed in 10 tumors.

RESULTS.—

SOX11 demonstrated positive staining in the undifferentiated PNET component of all tumors (10 of 10) and was rarely positive in the differentiated (ie, neuronal/glial) component (1 of 10; focal and weak); synaptophysin was slightly less sensitive in the undifferentiated component (12 of 13; often focal and weak) and also showed positivity in the neuronal/glial component (5 of 13). Glial fibrillary acidic protein and S100 were more frequently positive in the differentiated areas (83% and 77%, respectively) compared with undifferentiated areas (25% and 17%, respectively).

CONCLUSIONS.—

SOX11 is a sensitive immunohistochemical marker for testicular PNET, particularly those lacking differentiation. Testicular PNETs often demonstrate glial and/or neuronal differentiation. Differentiation is marked by the acquisition of S100 and glial fibrillary acidic protein expression and SOX11 loss.

A rare entity of Primary Ewing sarcoma in kidney

Background

Ewing sarcoma (ES) or primitive neuroectodermal tumors (PNET) represents a spectrum of poorly differentiated and aggressive malignancies. It rarely arises from the kidney and accounts for less than 1% of renal mass. Given the uncharacteristic clinical symptoms and imaging features, renal Ewing sarcoma (RES) is often diagnosed by postoperative pathology.

Case presentation

Herein, we depicted a case of RES, which was administrated in our institution by chief complaints of intermittent left plank pain and palpable abdominal mass. We demonstrated the aggressive behavior of this renal malignancy and summarized its therapeutic modalities and outcomes.

Conclusion

The diagnosis of RES relies on integrated analysis including histomorphology, immunohistochemical staining and confirmation of molecular-genetic testing. Despite the surgery and adjuvant therapy, optimized and potent therapeutic regimes are still urgently needed to improve the poor prognosis of RES.

Primary Ewing Sarcoma/Primitive Neuroectodermal Tumor of the Kidney: The MD Anderson Cancer Center Experience

Limited information exists on the clinical behavior of the Ewing sarcoma family of tumors (ESFT) of the kidney. We reviewed the records of 30 patients (aged 8-69 years) with ESFT of the kidney seen at our institution between 1990 and 2013. We analyzed the event-free survival (EFS) and overall survival (OS) for associations with patient demographics, disease group, tumor size, tumor thrombus, and treatment. Six patients (20%) had tumors confined to the kidney (Group I), seven (23.3%) had local tumor extension beyond the kidney (Group II), and 17 (56.7%) had distant metastasis at diagnosis (Group III). Twenty-five (83.3%) patients underwent radical (19 upfront, five delayed) or partial (one upfront) nephrectomy, 25 (83.3%) chemotherapy and four (13.3%) radiotherapy. The 4-year EFS and OS were 43% (95% CI, 26-61%) and 63% (95% CI, 46-81%), respectively. EFS and OS were significantly associated with disease group and chemotherapy (p < 0.039). The presence of tumor thrombus in renal vein and/or inferior vena cava was associated with worse EFS (p = 0.053). Patients with disease confined to the kidney treated with nephrectomy and adjuvant chemotherapy have favorable outcomes. Local tumor extension beyond the kidney, tumor thrombus, and distant metastasis are unfavorable factors that warrant intensification or novel approaches of therapy.

Primitive neuroectodermal tumour (PNET) of the renal capsule mimicking solid adrenal tumour

Primitive neuroectodermal tumour (PNET) of renal capsule is a rare entity. We report a case of a 17-year-old girl, who presented with symptoms of epigastric and right hypochondrium pain since 1 year. She was afebrile and physical examination revealed a soft, non-tender, firm, bimanually palpable and ballotable mass along right flank. Ultrasound abdomen showed a large heteroechoic mass in right suprarenal region with indistinct planes with upper pole of right kidney. On CT, a large right suprarenal mass was noted with origin likely from right adrenal gland. Surgery was done and intraoperatively, the large mass in right suprarenal region showed involvement of the upper pole of the right kidney. The right adrenal gland was small in size, compressed and displaced by the lesion. Histopathology revealed the mass to be PNET of kidney. We report the relevant imaging findings of the case with review of literature of this entity.

Outcome of multidisciplinary treatment of peripheral primitive neuroectodermal tumor

Peripheral primitive neuroectodermal tumors (PNETs) constitute very rare and aggressive malignancies. To date, there are no standard guidelines for management of peripheral PNETs due to the paucity of cases arising in various body sites. Therapeutic approach is derived from Ewing sarcoma family, which currently remains multimodal. Our study retrospectively analyzed 86 PNET patients from February 1, 1998 to February 1, 2018 at Peking Union Medical College Hospital with an additional 75 patients from review of literature. The clinicopathologic and treatment plans associated with survival was investigated. Surgery, chemotherapy, female sex, small tumor size, no lymph node metastasis, R0 surgical resection, (vincristine + doxorubicin + cyclophosphamide)/(isophosphamide + etoposide) regimen, and more than 10 cycles of chemotherapy were associated with improved overall survival in univariate analysis. Surgery, more than 10 cycles of chemotherapy, and small tumor size were independent prognostic factors for higher overall survival. Our data indicates that multimodal therapy is the mainstay therapeutic approach for peripheral PNET.

Retroperitoneal Sarcomas: An Update on the Diagnostic Pathology Approach

Retroperitoneal sarcomas are a heterogenous group of rare tumors arising in the retroperitoneum. Retroperitoneal sarcomas comprise approximately 10% of all soft tissue sarcomas. Though any soft tissue sarcoma histologic types may arise in the retroperitoneal space, liposarcoma (especially well-differentiated and dedifferentiated types) and leiomyosarcoma do so most commonly. Retroperitoneal sarcomas are diagnostically challenging, owing to their diversity and morphological overlap with other tumors arising in the retroperitoneum. An accurate diagnosis is necessary for correct management and prognostication. Herein, we provide an update on the diagnostic approach to retroperitoneal sarcomas and review their key histologic findings and differential diagnoses.

Renal Tumors of Childhood-A Histopathologic Pattern-Based Diagnostic Approach

Renal tumors comprise approximately 7% of all malignant pediatric tumors. This is a highly heterogeneous group of tumors, each with its own therapeutic management, outcome, and association with germline predispositions. Histopathology is the key in establishing the correct diagnosis, and therefore pathologists with expertise in pediatric oncology are needed for dealing with these rare tumors. While each tumor shows different histologic features, they do have considerable overlap in cell type and histologic pattern, making the diagnosis difficult to establish, if based on routine histology alone. To this end, ancillary techniques, such as immunohistochemistry and molecular analysis, can be of great importance for the correct diagnosis, resulting in appropriate treatment. To use ancillary techniques cost-effectively, we propose a pattern-based approach and provide recommendations to aid in deciding which panel of antibodies, supplemented by molecular characterization of a subset of genes, are required.

Primitive neuroectodermal tumor of the kidney: A rare case report

Renal primitive neuroectodermal tumor (PNET) is a rare primary renal neoplasm. Morphologically, it may mimic small blue round-cell tumor. Hence, histopathology in conjunction with immunohistochemistry plays a significant role in correctly diagnosing this malignancy. We report a case of PNET of kidney in a 30-year-old female with an extension to inferior vena cava, who succumbed following an aggressive course of illness.

Danger is only skin deep: aggressive epidermal carcinomas. An overview of the diagnosis, demographics, molecular-genetics, staging, prognostic biomarkers, and therapeutic advances in Merkel cell carcinoma

Merkel cell carcinoma (MCC) is a high grade primary cutaneous neuroendocrine carcinoma and is among the most aggressive cutaneous malignancies. The rising incidence of MCC, together with its often rapidly aggressive course, underscore a critical need to recognize the histopathologic and the immunohistochemical features that inform its accurate diagnosis. In the current review, we summarize the current state of knowledge regarding the accurate diagnosis of MCC and the exclusion of other entities in the differential diagnosis. We provide a comprehensive review of genomic studies that identified the molecular-genetic drivers of MCC as well as a summary of studies identifying prognostic biomarkers that can facilitate risk stratification. Importantly, Merkel cell polyomavirus (MCPyV) appears to be causative in most cases of MCC and represents both a diagnostic and prognostic marker. Finally, as staging of MCC has undergone critical refinements with the introduction of the 8th Edition of the American Joint Committee on Cancer staging system, we provide an update on MCC staging. In particular, the prognostic significance of the sentinel lymph node (SLN) in MCC necessitates a systematic approach to its evaluation and diagnosis to ensure accurate and consistent risk stratification for patients, and we therefore provide a comprehensive overview of SLN evaluation in MCC. Finally, the intimate relationship between MCC and the integrity of the host immune system has led to paradigm-shifting therapeutic advances with the successful application of immune checkpoint blockade to treat patients with advanced disease, and we therefore summarize those studies and the correlative studies in which predictive biomarkers have been identified.

Ewing Sarcoma With Emphasis on Extra-skeletal Ewing Sarcoma: A Decade's Experience From a Single Centre in India

INTRODUCTION

The diagnosis of Ewing sarcoma family of tumours (ESFT) is challenging, especially in adults and in extra-skeletal or visceral location. Several morphologic mimics with varied treatment options and prognosis confer diagnostic dilemmas. Application of ancillary diagnostic modalities in surgical pathology in clinical routine has enabled accurate diagnosis of ESFT in bone, soft tissues, and viscera.

AIM

The study aims to assess the clinicopathological features including molecular test results of ESFT with emphasis on sex, age, and location, especially extra-skeletal soft tissue and visceral location.

MATERIAL AND METHODS

Data of clinicopathological, molecular tests (wherever performed), diagnosis rendered in 302 ESFT over a decade from our centre were reviewed. Statistical comparison of skeletal and extra-skeletal tumours with reference to age and sex was done using SPSS package. The P value of <.05 was considered significant.

RESULTS

The cohort included 302 ESFTs with 49% skeletal and 51% extra-skeletal tumours. Thigh was most common site among skeletal tumours; chest wall, paraspinal location, and retroperitoneum among soft tissues (39.4%); and kidney, ovary, and cervix among visceral tumours (11.3%). Fluorescence in situ hybridisation for EWSR1 gene rearrangement was positive in 54 patients and reverse-transcriptase polymerase chain reaction in 19 patients. Predominance of male sex, younger age and location in extremities among skeletal tumours and lack of gender predilection, higher age and axial location in extra-skeletal tumours were noted, which were statistically significant. Molecular tests were performed more frequently in extra-skeletal tumours, especially in visceral tumours to establish the diagnosis.

CONCLUSIONS

The study showed statistically significant differences in the age, sex, and location between skeletal and extra-skeletal ESFT. The increased percentage of extra-skeletal tumours especially in viscera was attributed to the increased awareness and availability of ancillary techniques.

Ewing sarcoma and Ewing-like tumors

Ewing sarcoma (ES) and Ewing-like sarcomas are highly aggressive round cell mesenchymal neoplasms, most often occurring in children and young adults. The identification of novel molecular alterations has greatly contributed to a profound reappraisal of classification, to the extent that the category of undifferentiated round cell sarcoma has significantly shrunk. In fact, in addition to Ewing sarcoma, we currently recognize three main categories: round cell sarcomas with EWSR1 gene fusion with non-ETS family members, CIC-rearranged sarcomas, and BCOR-rearranged sarcomas. Interestingly, despite significant morphologic overlap, most of these entities tend to exhibit morphologic features predictive of the underlying molecular alteration. Ewing sarcoma is the prototype of round cell sarcoma whereas in CIC sarcomas, focal pleomorphism and epithelioid morphology can predominate. BCOR sarcomas often exhibit a spindled neoplastic cell population. NFATC2 sarcoma may exhibit remarkable epithelioid features, and PATZ1 sarcomas often feature a sclerotic background. The differential diagnosis for these tumors is rather broad, and among round cell sarcomas includes alveolar rhabdomyosarcoma, desmoplastic small round cell tumor, poorly differentiated round cell synovial sarcoma, small cell osteosarcoma, and mesenchymal chondrosarcoma. A combination of morphologic, immunohistochemical, and molecular findings allows accurate classification in most cases. A granular diagnostic approach to Ewing sarcoma and Ewing-like sarcomas is justified by significant differences in terms of both response to chemotherapy and overall survival. As all these entities are in part defined by specific fusion genes, a molecular diagnostic approach based on NGS technology should be considered. In consideration of the extreme rarity of many of these tumor entities, referral to expert rare cancer centers or to rare cancer networks represents the best strategy in order to minimize diagnostic inaccuracy, and allow proper patient management.

Primary renal Ewing's sarcoma in a young male treated completely by surgical excision without chemotherapeutic agents: Case report

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Primary renal Ewing sarcoma is a rare tumor in adults.

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Proper surgical resection is the most important treatment step.

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Further studies needed to establish treatment for this tumor.

Introduction

Primary renal Ewing’s sarcoma is a rare tumor with dismal prognosis. The main treatment modality of treatment is surgical excision with adjuvant or neoadjuvant chemotherapy.

Case presentation

We present a case of primary renal EWS in 27-year-old male. He presented to our center complaining of three days history of severe left flank pain associated with nausea and vomiting. Computerized tomography (CT) revealed a 10 × 7 × 6.5 cm left lower pole renal mass. Left radical nephrectomy was performed and revealed a tumor with uniform round to oval nuclei cells. The cells stained strongly positive for CD 99. The diagnosis was established as primary renal Ewing’s sarcoma. The patient refused the chemotherapy. Fortunately, he was free of the disease on regular clinical and radiological follow-up, the last follow up was 30 months post-nephrectomy.

Conclusion

This case highlights the importance of proper surgical treatment and its role in the managing this type of malignancy especially in localized disease at presentation.

Novel MEIS1-NCOA2 Gene Fusions Define a Distinct Primitive Spindle Cell Sarcoma of the Kidney

We describe 2 cases of a distinct sarcoma characterized by a novel MEIS1-NCOA2 gene fusion. This gene fusion was identified in the renal neoplasms of 2 adults (21-y-old male, 72-y-old female). Histologically, the resected renal neoplasms had a distinctively nodular appearance, and while one renal neoplasm was predominantly cystic, the other demonstrated solid architecture, invasion of perirenal fat, and renal sinus vasculature invasion. The neoplasms were characterized predominantly by monomorphic plump spindle cells arranged in vague fascicles with a whorling pattern; however, a more primitive small round cell component was also noted. Both neoplasms were mitotically active and one case showed necrosis. The neoplasms did not have a distinctive immunohistochemical profile, though both labeled for TLE1. The morphologic features are distinct from other sarcomas associated with NCOA2 gene fusions, including mesenchymal chondrosarcoma, congenital/infantile spindle cell rhabdomyosarcoma, and soft tissue angiofibroma. While we have minimal clinical follow-up, the aggressive histologic features of these neoplasms indicate malignant potential, thus warranting classification as a novel subtype of sarcoma.

Comprehensive Genomic Profiling of Adult Renal Sarcomas Provides Insight into Disease Biology and Opportunities for Targeted Therapies

BACKGROUND

Primary adult renal sarcomas (RSs) are rare aggressive neoplasms. Clinical outcomes are extremely poor, and optimal treatment remains challenging.

OBJECTIVE

To identify genomic alterations (GAs) in patients with RSs.

DESIGN, SETTING, AND PARTICIPANTS

Comprehensive genomic profiling (CGP) was conducted on DNA/RNA extracted from formalin-fixed paraffin-embedded tissue using the FoundationOne Heme/Sarcoma assay in 13 adult, locally advanced or metastatic RSs of various histologic types.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

All classes of GAs, including base substitutions, small indels, rearrangements, copy number alterations, tumor mutational burden (TMB), and microsatellite instability (MSI), were analyzed.

RESULTS AND LIMITATIONS

CGP revealed 55 GAs (4.2 per tumor), 29 of which were clinically relevant genomic alterations (CRGAs; 2.2 per tumor). At least one CRGA was detected in nine (69%) cases. High-level amplifications (more than six copies) involving 4q12 amplicon of the KIT and PDGFRA genes were identified in four (31%) cases (two undifferentiated pleomorphic sarcomas [UPSs], one sarcomatoid renal cell carcinoma, and one myxofibrosarcoma). Both UPSs also had KDR gene amplification in addition to KIT and PDGFRA. Additional CRGAs were found in CDKN2A/B (23%), NF1 (23%), and MET (8%). All RSs were MSI stable, the mean TMB was 3.5 mutations/megabase (Mb), and none (0%) featured TMB >10 mutations/Mb. Limitations include the small sample size.

CONCLUSIONS

RSs are characterized by diverse histology and genomic profiles including 31% of cases with 4q12 amplification harboring the KIT/PDGFRA/KDR genes. Of the tumors, 69% carry CRGAs, which could lead to potential benefit from targeted therapies; however, a low TMB also suggests that these cases are unlikely to respond to checkpoint inhibitors.

PATIENT SUMMARY

This study provides insights into molecular biology of renal sarcoma, a rare aggressive subtype of kidney tumors. We demonstrated that renal sarcomas harbor unique, recurrent, clinically relevant molecular abnormalities that provide new opportunities for targeted therapies.

Primitive neuroectodermal tumor of kidney with Level III inferior vena cava thrombus

Primitive neuroectodermal tumor (PNET) of the kidney is an extremely rare renal neoplasm with only about 50 reported cases in the literature. These tumors behave aggressively and carry a poor prognosis. A 22 years female patient presented with right lumber and right hypochondrium lump of 4 months duration. Commutated tomography revealed large right renal mass with renal vein and inferior vena cava (IVC) thrombus. Magnetic resonance imaging abdomen demonstrated the extension of tumor thrombus up to the junction of hepatic vein and IVC. Preoperative percutaneous needle biopsy was performed. Histopathology demonstrated small round to oval cells with scanty cytoplasm and cells are arranged in clusters. Immunohistochemical staining demonstrated a highly specific cluster of differentiation 99, confirming the diagnosis of a PNET.

Primitive neuroectodermal tumour with synchronous ipsilateral clear cell carcinoma of the kidney

We report the first case of a synchronous ipsilateral primitive neuroectodermal tumour (PNET) and clear cell renal cell carcinoma of the kidney. A 37-year-old man presented to the emergency department with a 24-hour history of colicky abdominal pain and visible haematuria. He had no relevant surgical or medical history. Physical examination was unremarkable apart from mild left flank tenderness. Triphasic CT of the abdomen and pelvis showed two solid lesions in the left kidney. Further staging CT of the chest showed no evidence of local or distal metastasis. He subsequently underwent laparoscopic radical nephrectomy. Pathological analysis of the kidney showed two synchronous renal tumours, a clear cell carcinoma and PNET of the kidney. The patient received adjuvant chemotherapy according to Ewing's sarcoma chemotherapy protocol. Surveillance CT scans at 3, 6 and 12 months showed no evidence of disease recurrence or metastasis.

Qualitative and quantitative CECT features for differentiating renal primitive neuroectodermal tumor from the renal cell carcinoma and its subtypes

OBJECTIVE:

To identify important qualitative and quantitative clinical and imaging features that could potentially differentiate renal primitiveneuroectodermal tumor (PNET) from various subtypes of renalcell carcinoma (RCC).

METHODS:

We retrospectively reviewed 164 patients, 143 with pathologically proven RCC and 21 with pathologically proven renal PNET. Univariate analysis of each parameter was performed. In order to differentiate renal PNET from RCC subtypes and overall RCC as a group, we generated ROC curves and determined cutoff values for mean attenuation of the lesion, mass to aorta attenuation ratio and mass to renal parenchyma attenuation ratio in the nephrographic phase.

RESULTS:

Univariate analysis revealed 11 significant parameters for differentiating renal PNET from clear cell RCC (age, p = <0.001; size, p =< 0.001; endophytic growth pattern, p < 0.001;margin of lesion, p =< 0.001; septa within the lesion, p =< 0.001; renal vein invasion, p =< 0.001; inferior vena cava involvement, p = 0.014; enhancement of lesion less than the renal parenchyma, p = 0.008; attenuation of the lesion, p = 0.002; mass to aorta attenuation ratio, p =< 0.001; and mass to renal parenchyma attenuation ratio, p =< 0.001). Univariate analysis also revealed seven significant parameters for differentiating renal PNET from papillary RCC. For differentiating renal PNET from overall RCCs as a group, when 77.3 Hounsfield unit was used as cutoff value in nephrographic phase, the sensitivity and specificity were 71.83 and 76.92 % respectively. For differentiating renal PNET from overall RCCs as a group, when 0.57 was used as cutoff for mass to aorta enhancement ratio in nephrographic phase, the sensitivity and specificity were 80.28 and 84.62 % respectively.

CONCLUSION:

Specific qualitative and quantitative features can potentially differentiate renal PNET from various subtypes of RCC.

ADVANCES IN KNOWLEDGE:

The study underscores the utility of combined demographic and CT findings to potentially differentiate renal PNET from the much commoner renal neoplasm, i.e. RCC. It has management implications as if RCC is suspected, surgeons proceed with resection without need for confirmatory biopsy. On the contrary, a suspected renal PNET should proceed with biopsy followed by chemoradiotherapy, thus obviating the unnecessary morbidity and mortality.

Metachronous renal Ewing sarcoma/primitive neuroectodermal tumour in a survivor of Burkitt lymphoma

We present a case of a 14-year-old girl who was diagnosed with Burkitt lymphoma in 2014. She was managed with chemotherapy and remained in remission for 3 years. On her surveillance imaging in 2017, a left-sided renal neoplastic mass was incidentally discovered. She underwent nephrectomy and pathology of the resected specimen revealed small cell tumour of the kidney with features favouring renal Ewing sarcoma/primitive neuroectodermal tumour. Molecular genetic analysis by fluorescence in situ hybridisation was performed which showed translocation of 22q12, thereby confirming the diagnosis. This is a rare secondary malignancy and an unusual association. This case highlights the importance and diagnostic dilemmas of rare secondary tumours in patients with such haematological malignancies and discusses its possible pathogenetic aspects.

Cytologic diagnosis of round cell sarcomas in the era of ancillary testing: an updated review

Round cell sarcomas constitute a large proportion of "small round blue cell tumors," which encompass a broad differential diagnosis and can be difficult to distinguish on cytomorphologic grounds alone. Numerous pathogenetic insights and advances in ancillary testing in soft tissue pathology over the last several decades have made accurate classification of soft tissue neoplasms increasingly feasible. Immunohistochemistry and genetic/molecular testing can now be performed on all cytologic preparations, including unstained smears, needle rinses, cell blocks, and liquid-based preparations, and this has greatly increased our diagnostic abilities. Nevertheless, there remain numerous diagnostic challenges, including variable sensitivity and specificity of available immunohistochemical markers, overlapping immunophenotypes between entities, and "promiscuity" of genetic alterations such as EWSR1 rearrangements, present in a multitude of tumor types. Herein we provide a review on the cytologic, immunohistochemical, and genetic features of the more frequently encountered round cell sarcomas, as well as recently described entities, with an emphasis on diagnostic pitfalls and judicious use of ancillary studies.

Primitive neuroectodermal tumors of the kidney

Ewing's sarcoma/primitive neuroectodermal tumor (ES/PNET) rarely occurs as a primary renal tumor. The disease affects young adults and children and has an aggressive course. The clinical presentation and imaging of these tumors are nonspecific, and they often present at an advanced stage. We present the clinical features, imaging, diagnosis, and treatment of 7 cases of renal PNET (4 men, 3 women; median age, 32 years). Common presenting symptoms were flank or abdominal pain and a mass in the abdomen. On imaging, a large heterogenous infiltrating renal mass with areas of calcification, hemorrhage, and necrosis and tumor thrombus can give a clue to the diagnosis of renal PNET. Immunohistochemistry and molecular studies are essential to confirm the diagnosis. The prognosis of renal ES/PNET is generally poor. Radical nephrectomy combined with chemotherapy and radiotherapy is the standard treatment for renal PNET. An early and accurate diagnosis is crucial for the proper management of these aggressive tumors.

Antiangiogenic therapy for primitive neuroectodermal tumor with thalidomide: A case report and review of literature

RATIONALE

Peripheral primitive neuroectodermal tumor (PNET) is a kind of small round cell tumor derived from primitive neuroectodermal tumor.

PATIENT CONCERNS

PNET is a highly malignant tumor that is subordinated to Ewing sarcoma. It occurs predominantly in soft tissue and bone and rarely in the bronchi and lung. Traditional surgery, radiotherapy, and chemotherapy are used for the treatment of PNET, but are usually ineffective.

DIAGNOSES

There was a rare case of a 17 year-old man diagnoses with primary pulmonary PNET.

INTERVENTIONS

The patient was treated by the remedy treatment with thalidomide after the poor effect of conventional radiotherapy and chemotherapy.

OUTCOMES

The patient survived without disease progression for 15 months and was in stable condition.

LESSONS

Thalidomide provides a choice for maintenance therapy in PNET.

Late onset of primary pulmonary primitive neuroectodermal tumor: a case report

Lungs are one of most metastatic areas for primitive neuroectodermal tumor (PNET), however primary pulmonary PNET is extremely rare. Here we present a case of a 58-year-old male patient with a tumor in the right lung that originated from the lung but not from chest wall. Patient was diagnosed with PNET following histological and immunohistochemical examination of CT-guided percutaneous tru-cut needle biopsy and no distant metastasis were detected in PET-CT scan. As advised recently in published literature, surgical resection following neoadjuvant chemotherapy protocol is preferred in the treatment of our patient as it has better success of complete resection leading to higher 5-year survival rates. Although primary pulmonary PNET is uncommon, it should be taken into account and complete surgical resection should be aimed as treatment to achieve higher survival rates.

Primary Ewing's sarcoma/primitive neuroectodermal tumor of the ileum: case report of a 16-year-old Chinese female and literature review

Background

Ewing’s sarcoma (ES) and primitive neuroectodermal tumors (PNET) are closely related tumors. Although soft tissue ES/PNET are common in clinical practice, they are rare in the small intestine. Because of the absence of characteristic clinical symptoms, they are easily misdiagnosed as other benign or malignant diseases.

Case presentation

Here, we present the case of a 16-year-old female who complained of anemia and interval hematochezia. Her serum test results showed only a slight elevation of CA-125 and a low level of hemoglobin. Computer tomography and magnetic resonance imaging revealed a cystic and solid mass in the lower abdominal quadrant and pelvic region, which prompted suspicion of a malignant gastrointestinal stromal tumor of the small intestine. After resection, the tumor’s histology and immunohistochemistry (positive for CD99, vimentin and synaptophysin) results suggested ES/PNET. Fluorescent in situ hybridization tests proved the breakpoint rearrangement of the EWSR1 gene in chr 22.Ultrastructural analysis revealed neurosecretory and glycogen granules in the tumor cell cytoplasm.

Conclusions

Together, these data supported the diagnosis of a rare case of localized ES/PNET in the small intestine without adjuvant chemo- or radiotherapy. To our knowledge, this is the first report from China of a primary small bowel ES/PNET in the English-language literature. In addition, on the basis of findings from previous publications and the current case, the optimal treatment for localized gastrointestinal ES/PNET is discussed.

Neuroendocrine neoplasms of the genitourinary tract in adults: cross-sectional imaging spectrum

Neuroendocrine (NE) neoplasms of the genitourinary (GU) tract in adults are rare tumors with distinct histopathology and variable biological behavior and imaging findings. They may be primary or metastatic in origin. The spectrum of primary GU tract NE neoplasms includes carcinoid, small cell carcinoma, large cell NE carcinoma, and paraganglioma. The tumors commonly show positivity to specific immunohistochemical markers and characteristic dense-core granules at the ultra-structural level. Although imaging findings are nonspecific and accurate differentiation from the more common malignancies of the individual organs is not possible, cross-sectional imaging modalities play an important role in the diagnosis, staging, and surveillance of these tumors. Somatostatin receptor scintigraphy (octreotide scan) may be useful in the detection and treatment of metastatic disease in select patients. Knowledge of the various NE tumors of the adult GU tract and familiarity with their pathological and imaging findings permit optimal patient management.

Primary Ewing Sarcoma / Primitive Neuroectodermal Tumor of the Kidney: A Clinicopathologic Study of 23 Cases

Primary Ewing sarcoma / primitive neuroectodermal tumor (ES) of the kidney is a rare neoplasm with limited clinicopathologic data. We report 23 such cases with no history of ES elsewhere in the body. The patients included 13 male and 10 female, aged 8-70 years (mean, 31 years). The average tumor size was 11.7 cm (range, 5-20 cm). Microscopic analysis showed predominantly lobular growth (n = 14), with focal papillary (n = 3), alveolar (n = 1), and hemangiopericytoma-like (n = 1) patterns. Several tumors (n = 11) exhibited robust mitotic activity (>10 mitoses/10 high-power fields). Necrosis (n = 13) and lymphovascular invasion (n = 14) were common. Homer Wright rosettes (n = 6) and perivascular pseudorosettes (n = 1) were also identified. The tumors invaded the renal sinus or perinephric fat (n = 11), renal vein (n = 13), and adrenal gland (n = 2). Molecular and fluorescence in situ hybridization analysis showed rearrangement of EWSR1 gene (10/10), associated with EWSR1-FLI1 gene fusion (7/10). All patients with follow-up information (n = 18) had metastasis, commonly in the lungs (n = 12) and bone (n = 6). Twelve patients died of disease in a mean of 21 months; 6 patients were alive at a mean of 49 months after diagnosis. Primary kidney ES usually present at an advanced stage with extrarenal spread and metastasis. Although renal ES share histologic, immunohistochemical, and molecular features with their bone and soft tissue counterparts, they appear to be more aggressive tumors with poorer clinical outcome.

Primitive neuroectodermal tumour of kidney with thrombosis of the inferior vena cava and good responsive to surgical and medical treatment: description of a case and revision of literature

Primitive neuroectodermal tumour (PNET) of kidney is a rare cancer typical of young adults with few cases described in the literature. We report a case of renal PNET in a 31-year-old man who presented to our department with a computed tomographic (CT)-scan revealing a large renal mass of 20 cm, massive thrombosis of the inferior vena cava (IVC). The patient underwent radical nephrectomy with contextual retroperitoneal lymphadenectomy and resection of IVC needing Dacron prosthesis substitution. Definitive histopathological examination showed PNET of kidney infiltrating ipsilateral adrenal gland, massive cava thrombosis with infiltration of vena cava wall and one lymph nodal metastasis. Postoperative PET-scan showed metastatic lesions in bilateral adrenal glands and pancreas. The patient received chemotherapy, and currently, he is in follow-up after 26 months from first diagnosis without any sign of recurrence of disease. Kidney PNET usually is associated with poor prognosis, so, it needs an early identification and differentiation from other similar small cells tumours in order to obtain a good response to the treatments.

CT Features and Pathological Correlation of Primitive Neuroectodermal Tumor of the Kidney

The purpose of the study was to analyze the computed tomography (CT) findings of primitive neuroectodermal tumor (PNET) of the kidney and correlate them pathologically. Ten cases of pathologically confirmed renal PNET were collected and retrospectively reviewed. The CT features that were analyzed include tumor size, shape, margins, density, nature of enhancement, presence of thrombosis, and metastasis, etc. These parameters were correlated with pathological findings and combined with literature review. The median age of the patients was 30 years. CT images showed solitary, large, ill-defined, irregular, or lobulated heterogeneous mass. Invasive growth toward the renal cortex and pelvis with renal cortical interruptions were seen in eight cases with one case exhibiting invasion that extended beyond the renal capsule with soft tissue seen in the perirenal fat pace. The tumors were confined to the kidney contour with enlargement of kidney in six of the cases. Cystic changes with mural nodules were detected in three cases. Eight cases showed persistent moderate enhancement during the nephrographic phase. Irregular septum-like structures were seen in four cases. Thrombosis was detected in eight cases. Lymph node metastasis was detected in eight cases with bilateral lung metastasis in two and bone metastasis in one. Renal PNET is a rare highly aggressive disease affecting younger people. It should be considered as a strong differential when well confined, yet large tumors that cause enlargement of the kidney are seen and also when tumors expressing cystic changes along with mural nodules are seen. Although renal PNET has certain other characteristic CT features, pathological and immunohistochemistry report must also be sought for definitive diagnosis.

Primary Renal Primitive Neuroectodermal Tumor/Ewing's Sarcoma Imaging and Pathologic Findings of a Patient with a Nine Year, Eight Month Disease Free Period: Case Report and Review of Literature

Introduction

Primitive neuroectodermal tumor (PNET)/Ewing’s sarcoma (EWS) belongs to a family of neoplasms that are presumed to originate from the neuroectodermal crest. PNET/EWSs are highly aggressive malignancies that usually present in the form of bone or soft tissue masses and usually affect adolescents and young adults. Primary PNET/EWS of the kidney is very rare.

Case Presentation

We present the case of a 32-year-old female patient with primary renal PNET/EWS diagnosed nine years and eight months earlier. The patient presented with acute flank pain in the left lumbar region, hematuria, and episodes of high body temperature of 40°C. Abdominal ultrasound (US) and subsequently performed computed tomography (CT) revealed a large renal mass of heterogenous structure. The kidney tumor had central necrotic hypodense areas and strongly peripherally enhanced solid parts on postcontrast CT images. Immunohistochemistry revealed positivity for CD99 and neuron-specific enolase (NSE). Tumor cells were negative for CD3, CD 20, chromogranin, synaptophysin, vimentin, and neurofilament. Reverse transcription polymerase change reaction (RT-PCR) revealed EWS/FL1 translocation type 2. The patient underwent nephrectomy and polychemotherapy. The follow-up nine years and eight months after the diagnosis showed no evidence of tumor.

Conclusions

PNET/EWS should be included in the differential diagnosis of renal tumors in symptomatic young adults. Patients with localised PNET/EWS treated with a combination of surgery and chemotherapy have an excellent chance of long-term survival, as in the case we have presented.