Imaging Findings of Primitive Neuroectodermal Tumors of the Kidney:

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.

Experience of CT diagnosis and management of primary renal Ewing's sarcoma: A retrospective analysis of 6 cases and a literature review

To present the clinical experience of primary renal Ewing's sarcoma/primitive neuroectodermal tumors (rEWs/PNET) admitted to our hospital and systematically review the published literature. A retrospective analysis was performed on patients with pathologically confirmed renal EWs/PNET (rEWs) in our hospital, and the literature on rEWs published in PubMed and Embase databases before March 1, 2022 was searched for analysis. A total of 337 rEWs were included in the statistical analysis, including 6 cases of our patients and 331 cases published in the literature. The common clinical symptoms of rEWs are abdominal pain, hematuria, abdominal mass and so on. computed tomography (CT) plays an important role in the diagnosis of rEWs, and the typical manifestation is a large heterogeneous soft tissue density mass, with a specific "septum-like" enhancement in contrast-enhanced scan. The 2-year overall survival rate of rEWs was 48%, with a median survival time of 18 months. "Septum-like" enhancement on CT can be used as a relatively specific sign for the differential diagnosis of rEWs from Wilms tumor and neuroblastoma. The maximum diameter of the rEWs was usually greater than 10 cm, the clinical symptoms of weight loss, metastasis at diagnosis, tumor thrombogenesis of renal vein or/and inferior vena cava tumor, and the failure to undergo radical nephrectomy were the factors of poor prognosis. The incidence of primary rEWs is low and the prognosis is poor. Early diagnosis and radical nephrectomy combined with chemotherapy is the key to improve the prognosis of patients, and CT plays an important role in early diagnosis.

Atypical CT findings of renal neuroblastoma: a case report

BACKGROUND

The neuroblastoma (NB) is a highly malignant tumor of the ectoderm of sympathetic nerve cells and one of the most common malignant tumors in children, which can occur in any part of the sympathetic nerve plexus distribution, however it is less common in the kidney.

CASE DESCRIPTION

Here we present a case of a 4-year-old boy who came to our hospital for medical help because of "abdominal distension for 1 day". Abdominal computed tomography (CT) revealed a huge retroperitoneal soft tissue mass with unclear boundaries with kidneys and adrenal glands, and low-density cystic necrosis areas were seen in the tumor. Contrast-enhanced scan showed that the mass showed mild heterogeneous enhancement. Based on these findings in the patient, he was initially considered to have Wilms tumor, but was finally pathologically confirmed as renal NB. The purpose of this article is to provide the clinicopathological features and CT manifestations of renal NB, and to discuss its differential diagnosis with other renal tumors, in order to better provide clinicians with a better understanding of the rare solid tumor. The renal NB is usually a large lobulated soft tissue mass with unclear boundary and incomplete capsule, which is prone to hemorrhage, necrosis, cystic degeneration and calcification. On CT, the mass is usually isodensity or slightly hypodense, and the cystic degeneration and necrosis area is hypodense, and on contrast-enhanced scan, it can be mildly to significantly enhanced, but the cystic degeneration and necrosis area have no enhancement.

CONCLUSIONS

The CT findings of our case were atypical and overlapped with those of Wilms, so our case suggests that renal NB should be considered as one of the differential diagnoses of Wilms, the most common malignancy of the kidney in children.

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.

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.

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.

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.

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.

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.

Sonography and Transthoracic Echocardiography for Diagnosis of Systemic Cardiovascular Metastatic Tumor Thrombi

Sonography and transthoracic echocardiography (TTE) are seldom used for assessment of metastatic tumor thrombi in the cardiovascular system in routine clinical practice. We performed this retrospective study to evaluate the combination of sonography with TTE for diagnosis of metastatic tumor thrombi in heart and systemic vessels. Vascular, abdominal, pelvic, and small-part sonography was applied in 18 patients, and TTE was conducted simultaneously in 14 patients. Tumor thrombi invaded into the inferior vena cava system in 12 patients, superior vena cava system in 5 patients, and aorta in 1 patient; they extended to the right cardiac chambers in 11 patients. Six patients had diagnoses by pathologic examination. The primary neoplasms were identified by conventional imaging in 17 patients. The morphologic and echogenic characteristics of the tumor thrombi were diverse and depended on their original tumors. The thrombi were either contiguous or discrete from the original tumors. The neoplastic vascularity of the thrombi and the invasive extension were the primary characteristics that distinguished them from bland thrombi. Simultaneous application of sonography and TTE is a feasible way to comprehensively evaluate cardiovascular metastatic tumor thrombi in most patients.

CT and MRI Findings in a Rare Case of Renal Primitive Neuroectodermal Tumor

BACKGROUND

Primary renal primitive neuroectodermal tumor/extraskeletal Ewing's sarcoma (PNET/EES) is a very rare renal tumor.

CASE REPORT

We report a case of primary renal PNET/EES of the kidney in an adult patient and describe its computed tomography and magnetic resonance imaging findings, including diffusion weighted images along with a review of the current medical literature.

CONCLUSIONS

Although very rare, a relatively large renal mass which shows very infiltrative growth pattern on CT and MR imaging and striking diffusion restriction should raise the suspicion of a renal primitive neuroectodermal tumor, in a young adult.

[Primitive neuroendocrine/ectodermal kidney tumor]

PNET of the kidney are rare, aggressive tumors that occur mainly in adolescents. The diagnosis of PNET is difficult, but is possible with pathognomonic radiological findings. Since a radical nephrectomy is generally not sufficient for PNET of the kidney, early diagnosis and treatment is essential for successful recovery.

Renal Primitive Neuroectodermal Tumor: A Case Report

Primitive neuroectodermal tumor (PNET) is a malignant small round cell tumor and typically arises from bone or soft tissue in adolescents and young adults. Renal PNET is extraordinarily rare and exhibits highly aggressive biological behavior with poor prognosis.We present here a new case of renal PNET in a 31-year-old female. The patients were referred to our hospital because of left flank pain with nausea and vomiting for 1 week. A computed tomography scan revealed a 14.7 × 12.7 cm well-defined, unevenly mass lesion with both solid and cystic components and the tumor was not enhanced uniformly.A preoperative diagnosis of cystic renal cell carcinoma and urinary tract infection was made. The patient undergone anti-inflammatory therapy followed by a left radical nephrectomy. Taken with morphological pattern and immunohistochemical markers, a diagnosis of renal PNET was made. Two cycles of combined chemotherapy were executed. At the 14-month follow-up, no evidence of metastasis or recurrence was indicated.This case reminds clinicians that for adolescents and young adults with a suspicious renal mass, a diagnosis of renal PNET should be always considered. An initial surgery followed by radiotherapy and chemotherapy is suggested for the therapeutic management.

Unusual Malignant Solid Neoplasms of the Kidney: Cross-Sectional Imaging Findings

Malignant kidney neoplasms are the most frequently encountered solid kidney masses. Although renal cell carcinoma is the major renal malignancy, other solid malignant renal masses should be considered in the differential diagnosis of solid renal masses that do not contain a macroscopic fatty component. In this pictorial essay, we present the imaging findings of a primitive neuroectodermal tumor, primary liposarcoma of the kidney, primary neuroendocrine tumor, leiomyosarcoma, synovial sarcoma, malignant fibrous histiocytoma, sclerosing fibrosarcoma and renal metastasis of osteosarcoma.

Appearance of extraosseous pelvic Ewing sarcoma on triphasic bone scan

A 24-year-old man with extraosseous Ewing sarcoma in the pelvis underwent a triphasic bone scintigraphy to rule out bone metastases and local bone infiltration before chemotherapy. The bone scintigraphy showed tracer uptake in the tumor in all 3 phases.

Primitive neuroectodermal tumor of the kidney: a single-institute series of six patients from China

OBJECTIVE

Renal primitive neuroectodermal tumor (PNET) is a rare and highly malignant neoplasm. Our study aims to present the clinical findings and prognosis of 6 patients with renal PNET from China.

MATERIAL AND METHODS

From January 2003 to February 2012, 6 patients with renal PNET confirmed by immunohistochemical staining and fluorescence in situ hybridization (FISH) treated in our institution were reviewed retrospectively and our data compared with the literature.

RESULTS

There were 4 male and 2 female patients with a mean age of 35.0 years. The mean diameter was 13.3 cm. Five of the masses had renal vein thrombosis, and 3 extended into the inferior vena cava. A lymph node metastasis was detected in 1 patient and a liver metastasis in another patient. Radical nephrectomy was performed in all cases, with 5 patients following chemotherapy and 1 receiving Sutent treatment. Within a median follow-up of 7.5 months (range 1-71), median overall survival was 22.1 months.

CONCLUSIONS

The diagnosis of renal PNET should be considered in young patients presenting with renal mass and venous thrombosis. It seems that Asian renal PNET patients had a higher rate of venous thrombosis than Caucasian populations. CD99 positivity on immunohistochemistry and EWS-FL1 chimera gene detected by FISH support the diagnosis. The prognosis is poor despite multimodal treatment.

Common and less-common renal masses and masslike conditions

As an increasing number of imaging examinations are performed, a greater number of incidental renal lesions are detected. Apart from the usual cysts and solid renal cell carcinomas, a variety of unusual benign and malignant renal lesions exist. Imaging is invaluable in characterizing these lesions and is confirmatory in some benign lesions. Renal cell carcinoma remains the diagnosis of exclusion; however, assessment of the imaging pattern in the appropriate clinical context can improve diagnostic accuracy. The objective of this article is to familiarize the radiologist with the imaging appearance of unusual non-neoplastic and neoplastic lesions and correlate with histopathologic studies when available.

Sarcomas of abdominal organs: computed tomography and magnetic resonance imaging findings

Sarcomas originating from abdominal organs are extremely rare, and literature in which investigators focus on their imaging features is scarce. This article aims to review the computed tomography and magnetic resonance imaging features of these rare tumors and to help in clinical diagnosis. Various sarcomas (eg, angiosarcoma, undifferentiated embryonal sarcoma, leiomyosarcoma, carcinosarcoma, rhabdomyosarcoma) originating, respectively, from different abdominal visceral organs (liver, pancreas, spleen, kidney, adrenal gland, uterus, and prostate gland) are reviewed along with cases we encountered.

Primitive neuroectodermal tumor/Ewing's sarcoma in adult uro-oncology: A case series from a developing country

Peripheral primitive neuroectodermal tumor/Ewing's sarcoma (PNET/EWS) is primarily a tumor of soft tissues and bones. Primary localization of PNET/EWS in genitourinary organs is rare. No data on this localization of PNET/EWS are available in literature from Pakistan. We searched our adult uro-oncology records from 1994 till date and identified all cases of adult genitourinary and adrenal PNET/EWS diagnosed on histology and immunohistochemistry. Their case records were reviewed to obtain data on demographics, presentation, pathologic features, management and outcome. Six cases were found; all were young and had aggressive disease at presentation. Four had renal PNET/EWS. One case each of prostate and adrenal PNET/EWS was seen. Surgery and chemotherapy formed the mainstay of management. Three patients (50%) died during treatment, two were lost to follow-up and one case with renal PNET/EWS showed good initial response to chemotherapy but was later on lost to follow-up. In conclusion, PNET/EWS should be considered in the differential diagnosis of genitourinary malignant tumors in young patients. These tumors are aggressive with poor outcome.