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Non-invasive differentiation of paediatric kidney tumours is particularly important in the SIOP-RTSG protocols, which recommend pre-operative chemotherapy without histological confirmation. The identification of clinical and tumour-related parameters may enhance diagnostic accuracy. Age, metastases, and tumour volume (TV) were retrospectively analysed in 3306 patients enrolled in SIOP/GPOH 9, 93-01, and 2001 including Wilms tumour (WT), congenital mesoblastic nephroma (CMN), clear cell sarcoma (CCSK), malignant rhabdoid tumour of the kidney (MRTK), and renal cell carcinoma (RCC). WT was diagnosed in 2927 (88.5%) patients followed by CMN 138 (4.2%), CCSK 126 (3.8%), MRTK 58 (1.8%) and RCC 57 (1.7%). CMN, the most common localized tumour (71.6%) in patients younger than 3 months of age, was diagnosed earliest and RCC the latest (median age [months]: 0 and 154, respectively) both associated with significantly smaller TV (median TV [mL]: 67.2 and 45.0, respectively). RCC occurred in >14% of patients older than 120 months or older than 84 months with TV <100 mL. Receiver operating characteristic analyses discriminated WT from CMN, RCC and MRTK regarding age (AUC = 0.976, 0.929 and 0.791) and TV (AUC = 0.768, 0.813 and 0.622). MRTK had the highest risk of metastasis (37.9%) despite young age, whereas the risk of metastasis increased significantly with age in WT. Age and TV at diagnosis can differentiate WT from CMN and RCC. MRTK must be considered for metastatic tumours at young age. Identification of CCSK without histology remains challenging. Combined with MRI-characteristics, including diffusion-weighted imaging, and radiomics and liquid biopsies in the future, our approach allows optimization of biopsy recommendations and prevention of misdiagnosis-based neoadjuvant treatment., (© 2024 The Authors. International Journal of Cancer published by John Wiley & Sons Ltd on behalf of UICC.)

Background: Tumors are rare in neonatal age. Congenital mesoblastic nephroma (CMN) is a usually benign renal tumor observed at birth, or in the first months of life. It may also be identified prenatally and associated with polyhydramnios leading to preterm delivery. Effective treatment is surgical in most cases, consisting in total nephrectomy. In literature, very few studies report on the neonatal management of such a rare disease, and even less are those describing its uncommon complications., Cases Presentation: We report on two single-center newborns affected with CMN. The first patient is a preterm female baby, born at 30 + 1 weeks of gestation (WG) due to premature labor, with prenatal (25 WG) identification of an intra-abdominal fetal mass associated with polyhydramnios. Once obtained the clinical stability, weight gain, instrumental (computed tomography, CT, showing a 4.8 × 3.3 cm left renal neoformation) and histological/molecular characterization of the lesion (renal needle biopsy picture of classic CMN with ETV6-NTRK3 translocation), a left nephrectomy was performed at 5 weeks of chronological age. The following clinical course was complicated by intestinal obstruction due to bowel adherences formation, then by an enterocutaneous fistula, requiring multiple surgical approaches including transitory ileo- and colostomy, before the conclusive anastomoses intervention. The second patient is a 17-day-old male term baby, coming to our observation due to postnatal evidence of palpable left abdominal mass (soon defined through CT, showing a 7.5 × 6.5 cm neoformation in the left renal lodge), feeding difficulties and poor weight gain. An intravenous diuretic treatment was needed due to the developed hypertension and hypercalcemia, which regressed after the nephrectomy (histological diagnosis of cellular CMN with ETV6-NTRK3 fusion) performed at day 26. In neither case was chemotherapy added. Both patients have been included in multidisciplinary follow-up, they presently show regular growth and neuromotor development, normal renal function and no local/systemic recurrences or other gastrointestinal/urinary disorders., Conclusions: The finding of a fetal abdominal mass should prompt suspicion of CMN, especially if it is associated with polyhydramnios; it should also alert obstetricians and neonatologists to the risk of preterm delivery. Although being a usually benign condition, CMN may be associated with neonatal systemic-metabolic or postoperative complications. High-level surgical expertise, careful neonatological intensive care and histopathological/cytogenetic-molecular definition are the cornerstones for the optimal management of patients. This should also include an individualized follow-up, oriented to the early detection of any possible recurrences or associated anomalies and to a better quality of life of children and their families., (© 2023. Società Italiana di Pediatria.)

Background: Congenital mesoblastic nephroma (CMN) is a rare tumour of the kidney with an overall excellent prognosis. Once considered a benign tumour, it is now recognized to carry a risk of recurrence and metastases with subsequent poor outcomes. The potential for genetic aberrations such as ETV6-NTRK3 fusion raises the potential for targeted treatments in certain patients. The optimum mode and frequency of surveillance is unclear. This study aims to assess this institution's experience with CMN and long-term outcomes., Methods: A single centre retrospective review was performed of all confirmed cases of CMN between October 2001 and January 2021., Results: Nine cases of CMN in patients under 12 months of age were identified. The histopathology, management and outcomes of these patients are discussed., Conclusion: CMN overall has a very good prognosis, but a subgroup does exist that will have poor outcomes. It is difficult to accurately identify this group to target adjuvant therapy., (© 2022 Royal Australasian College of Surgeons.)

Congenital mesoblastic nephromas are rare renal tumours that are encountered in paediatric age group. A term female neonate at the end of first week of life presented with bilateral lower limb swelling. On radiological evaluation, ultrasonography revealed an intra-abdominal mass which was managed with radical nephroureterectomy. Histopathological examination confirmed a diagnosis of congenital mesoblastic nephroma of mixed subtype., Keywords: case reports; congenital mesoblastic nephroma; kidney neoplasms; nephrectomy.

Background: Pediatric non-Wilms renal tumors (NWRTs), which comprise a small proportion of renal tumors, are a heterogeneous group of neoplasms with variable malignant potential, mortality, and response to treatment. We performed this study to determine the clinical characteristics, management and prognosis of children with Pediatric NWRTs., Methods: Medical records of all patients (n = 139) treated for NWRTs over a 12-year period (2008.01-2019.10) at a single center were reviewed retrospectively., Results: The histopathological groups of NWRTs included malignant rhabdoid tumor of the kidney (MRTK) (n: 30, 21.6%), renal cell cancer (RCC) (n: 26,18.7%), clear cell sarcoma of the kidney (CCSK) (n: 24,17.3%), congenital mesoblastic nephroma (CMN) (n: 21,15.1%), cystic nephroma (CN) (n: 16,11.5%), metanephric tumors (n: 12, 8.6%), renal angiomyoliporma (RAML) (n: 3, 2.2%), renal primitive neuroectodermal tumor (n: 2, 1.4%), renal hemangioma (n: 2, 1.4%), inflammatory myofibroblastic tumor (n: 2, 1.4%), ossifying renal tumor of infancy (ORTI) (n: 1, 0.7%). The distribution of all malignant NWRTs, including MRTK, CCSK, RCC and PNET, according to stage was as follows: stages I (n = 26), II (n = 16), III (n = 29), and IV (n = 11). The summary table shows the treatment offered to children with NWRTs. A total of 123 children were followed up for an average of 42 months. Sixteen children were lost to follow-up. Tumor-free survival was observed in 94 children. One patient who suffered from RCC is currently receiving targeted therapy and survives with the tumor. Twenty-eight children (22.8%) died., Conclusions: Pediatric NWRTs comprise 19.1% of all renal tumors in our single center. Most NWRTs can readily be distinguished using a range of immunohistochemical markers. Molecular genetic profiling has allowed much progress in the understanding of this group of tumors, making diagnosis and classification less difficult. The mainstay treatment of malignant NWRTs, including MRTK, CCSK, RCC and PNET, is comprehensive treatment. The mainstay treatment of benign NWRTs, including RAML, CN, ORTI, CMN, metanephric tumors, and renal hemangioma, is surgical resection alone and when the tumor diameter is smaller than 7 cm and the tumor locates in one pole, NSS can be performed., (© 2022. The Author(s).)

Background: Congenital mesoblastic nephromas mainly present as asymptomatic abdominal masses, but some present hematuria, hypertension or hypercalcemia. Neonatal dyspnea in an early-birth neonate due to rapid tumor growth is reported here for the first time., Case Presentation: A renal tumor and polyhydramnios were detected by ultrasonography of a male fetus at 32 weeks and 3 days of gestation. The mother had abdominal distension due to the polyhydramnios and signs of imminent premature birth. Amniocentesis was performed and the signs of imminent preterm birth subsided, but growth of the renal tumor was noted as a potential cause of respiratory dysfunction. Cesarean section was performed at 36 weeks and 2 days of gestation. His birthweight was 2638 g and his 1 and 5 min APGAR scores were 2 and 4 points, respectively. There was no spontaneous breathing at birth and he had remarkable abdominal distention. He underwent cardiopulmonary resuscitation. After circulation stabilized, emergency surgery was performed because of progressive hypoxemia and respiratory acidosis. Laparotomy revealed a huge tumor arising from the right kidney and right nephrectomy was performed. Histopathological examination led to diagnosis of congenital mesoblastic nephroma. The respiratory condition and circulatory dynamics stabilized after the pressure on the thorax from the tumor was relieved by surgery. The postoperative course was uneventful. No recurrence or complications have been observed in the 36 months since the surgery., Conclusions: Congenital mesoblastic nephroma can rapidly increase in size from the fetal period and may cause respiratory oncologic emergency, although there is relatively good prognosis., (© 2022. The Author(s).)

Purpose of Review: Our goal was to summarize current literature related to imaging of intra-abdominal genitourinary tumors diagnosed in the prenatal or neonatal period. Our specific interests included modalities used, diagnoses made, changing incidence of tumor detection, and proposed future uses of these imaging modalities., Recent Findings: Fetal and neonatal MRI have been used as an adjunct to ultrasound for better characterization and assessment of congenital mesoblastic nephroma, juvenile granulosa cell tumor, and other tumors. Despite recent literature describing fetal and neonatal MRI, it is not yet possible to determine whether its use is changing the incidence of tumor detection. Improvements in imaging technology, specifically the use of fetal MRI, have allowed for earlier identification of genitourinary masses with improved capability for diagnosis, surveillance, surgical planning, and sometimes prenatal treatment of the malignancy and related diagnoses, with a goal of preventing pregnancy and delivery complications., (© 2022. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Congenital mesoblastic nephroma is a rare pediatric renal tumor and has been reported in patients presenting with palpable abdominal mass, arterial hypertension, hematuria, polyuria, or hypercalcemia. Here we present the case of a 1-month-old neonate with suspected parathyroid hormone (PTH)-related peptide (PTH-rp)-mediated severe hypercalcemia revealing congenital mesoblastic nephroma. Preoperatively, hypercalcemia was corrected with hydration, furosemide, pamidronate, and low-calcium infant formula. Unilateral nephrectomy led to the resolution of hypercalcemia, transient hyperparathyroidism, and transient vitamin D and mineral supplementation. We conclude that congenital mesoblastic nephroma can secrete PTH-rp that can cause severe hypercalcemia., Competing Interests: Declaration of Competing Interest The authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest, or non-financial interest, in the subject matter or materials discussed in this manuscript., (Copyright © 2021 French Society of Pediatrics. Published by Elsevier Masson SAS. All rights reserved.)

Rationale: Fetal congenital mesoblastic nephroma (CMN) is a rare renal tumor, characterized by polyhydramnios, premature birth, and neonatal hypertension. In the prenatal stage, it is particularly difficult to diagnose CMN either by ultrasonography or magnetic resonance imaging (MRI). Thus, CMN is frequently detected in the third trimester in the clinical scenario., Patient Concerns: A 29-year-old G2P0 pregnant woman took routine prenatal examinations in our hospital. The fetal right kidney abnormality was not observed after 2 systematical ultrasonic examinations (at 24 and 31 weeks of gestation respectively), and only an increase was noticed in the amniotic fluid index (from 19.3 to 20.8 cm)., Diagnosis: CMN was detected by antenatal ultrasonography and MRI as a fetal right renal mass at 35 weeks of gestation in our hospital., Interventions: The pregnant woman was admitted at a gestational age of 38 weeks and 5 days due to alterations in renal function. Further, the pregnant woman was administered with "oxytocin" to promote delivery, and the neonate underwent a right nephrectomy on the 9th day after birth., Outcomes: The pathological examination confirmed a cellular type of right CMN. The neonate recovered well after operation without adjuvant treatment. During 6 months of follow-up, the neonate grew well and showed no signs of recurrence or metastasis., Conclusion: Polyhydramnios detected during prenatal examination required attention due to the risk of malformation of fetal urinary system. Prenatal ultrasonography combined with MRI could not only clearly identify the origin of the tumor, but also distinguish the correlation between the tumor and adjacent structures, thereby leading to early diagnosis and favorable prognosis., Competing Interests: The authors have no conflicts of interest to disclose., (Copyright © 2021 the Author(s). Published by Wolters Kluwer Health, Inc.)

Congenital mesoblastic nephroma (CMN) is a rare tumor of infancy. CMNs can be histologically divided into classic, cellular, and mixed subtypes. Cellular CMNs are difficult to differentiate from Wilms tumors. Herein, a neonate with cellular CMN accompanied by macroscopic hematuria, is described. The clinical, pathological, and imaging features of the disease are discussed.

Soyaltın E, Alaygut D, Alparslan C, Özdemir T, Arslansoyu-Çamlar S, Mutlubaş F, Kasap-Demir B, Yavaşcan Ö. A rare cause of neonatal hypertension: Congenital mesoblastic nephroma. Turk J Pediatr 2018; 60: 198-200. A rare cause of neonatal hypertension: Congenital Mesoblastic Nephroma (CMN) is a rare renal tumor in childhood and has been reported with palpable abdominal mass, hypertension, hematuria, polyuria and hypercalcemia. Histopathologically it has been classified into two histological types: classic and cellular. We present a 32-week gestation infant and his histopathology reports of cellular CMN presented with refractory hypertension.

Wilms tumor (WT) is the most prevalent pediatric renal tumor and most commonly occurs between ages 1 and 5 years. Data are lacking on children younger than 12 months with renal tumors. The cancer registry at the authors' institution was queried to identify patients 12 months and younger with renal masses. Demographics, clinical presentation, histopathology, stage, and survival outcomes were reviewed. The most common presenting symptoms included an asymptomatic abdominal mass (73%) and hematuria (9%). Histopathology revealed WT in 73% of patients, mesoblastic nephroma in 20%. Of those infants younger than 1 month of age, mesoblastic nephroma was the most common histopathology (68%). The 5-year overall survival (OS) was 93%, and 5-year event-free survival (EFS) was 93% for the entire group. For patients with WT, 5-year OS was 88% and 5-year EFS was 83%. Outcomes for congenital mesoblastic nephroma were excellent with 5-year OS and EFS of 100%. Reasons for good prognosis may be multifactorial and may include frequent well child checks in the first year of life and favorable histology. Patients in this age group are more likely to be classified as very low risk and may be treated with surgical resection alone.

Introduction  Children with unilateral renal tumor (URT) and preoperative renal dysfunction (PRD) may benefit from nephron-sparing surgery (NSS). To test this hypothesis, we studied the outcome of baseline renal function after nephrectomy or NSS among children with URT. Materials and Methods  Retrospective records review of children with URT who underwent nephrectomy (25 children) or NSS (11 children) at our institution. We analyzed the estimated glomerular filtration rate (eGFR) changes over time among patients, stratified by both preoperative renal function (with or without PRD) and surgical extent (NSS vs. nephrectomy). The primary end point was evaluation of compensatory recovery of preoperative eGFR after surgery. Only children older than 2 years at surgery were included in the study. Renal dysfunction was defined as an eGFR < 90 mL/min/1.73 m 2 . Results  After nephrectomy or NSS, patients with PRD presented, on average during adolescence, a significant increase in eGFR, whereas patients without PRD presented, on average during adolescence, a stable eGFR. However, after nephrectomy, 5 of 17 (29%) and 7 of 8 (87%) adolescent patients with baseline eGFR ≤ or > 100 mL/min/1.73 m 2 , respectively, achieved or maintained two-kidney eGFR values (T-KEV) ( p  = 0.01). After NSS, four adolescent patients with PRD and seven without PRD achieved or maintained T-KEV. Conclusion  The majority of children with URT and low baseline eGFR present with an impaired renal function recovery after nephrectomy and may benefit from NSS. Collaborative studies are needed to support present findings., (Georg Thieme Verlag KG Stuttgart · New York.)

Congenital mesoblastic nephroma (CMN) is the most common renal tumor of infancy; however, it occurs infrequently with an incidence of 1 : 125,000. The cellular and classical variants are the most common subtypes of tumors, with a mixed variant occurring infrequently. We describe two cases of mixed variant CMN, which presented within days of each other differing in their clinical behavior. The first case followed a typical course, previously described in the literature, while the other deviated significantly. Traditionally, CMN presents as large abdominal mass in the neonatal period associated with a paraneoplastic syndrome, which can result in hypertension or hypercalcemia. Surgical resection is curative in most cases and long-term prognosis is excellent. Hypertension rarely persists after removal of the tumor, but remained in one of our two patients.

Mesoblastic nephroma is an uncommon renal tumor of infancy and rarely occurs in adults. We report a case of mesoblastic nephroma in adult. A 22-year-old woman, who presented with left flank pain, was found to have a left renal mass by abdominal ultrasonography. Computed tomography revealed a heterogeneous tumor. Left radical nephrectomy was performed. The tumor was a creamy white solid mass. Microscopically, the tumor was composed of spindle cell proliferation. Atypia and mitoses were not identified. Among the tumor cells, there were tubular arranged epithelial elements. The patient was free of recurrence 18 months postoperatively. Mesoblastic nephroma is classified as a benign tumor but recurrence and malignant transformation of this tumor have been reported, so regular postoperative follow up is required.

Renal masses in children may be discovered during routine clinical examination or incidentally during the course of diagnostic or therapeutic procedures for other causes. Renal cancers are rare in the pediatric population and include a spectrum of pathologies that may challenge the clinician in choosing the optimal treatment. Correct identification of the lesion may be difficult, and the appropriate surgical procedure is paramount for lesions suspected to be malignant. The purpose of this article is to provide a comprehensive overview regarding the spectrum of renal tumors in the pediatric population, both benign and malignant, and their surgical management., (Copyright © 2015 by the American Academy of Pediatrics.)

Various fetal or placental disorders cause Ballantyne's (mirror) syndrome. For the first time, we report a maternal manifestation of Ballantyne's syndrome occurring concomitantly with the development of fetal congenital mesoblastic nephroma (CMN). In a pregnant woman with a CMN fetus, lung edema, hypertension, hyperthyroidism, and high serum human chorionic gonadotrophin level occurred, all of which characterize maternal manifestation of Ballantyne's syndrome. The fetus and placenta were devoid of 'edema', lacking 'triple edema', and thus this condition was not diagnosed as Ballantyne's syndrome; however, we considered this condition as the maternal manifestation of Ballantyne's syndrome. We performed emergent cesarean section at 28 weeks. Delivery acutely ameliorated maternal symptoms. Tumor was resected and was confirmed as CMN. Maternal manifestations of Ballantyne's syndrome, such as lung edema and hypertension, can occur in a mother with fetal CMN even without fetal and/or placental edema. The clinical course of this patient may suggest an etiology of Ballantyne's syndrome., (© 2014 The Authors. Journal of Obstetrics and Gynaecology Research © 2014 Japan Society of Obstetrics and Gynecology.)

Congenital renal tumours are rare and usually benign. Polyhydramnios is the most common mode of presentation. Although most cases have been diagnosed postnatally, with advances in imaging technology, an increasing number of cases are being detected on antenatal scans. We describe a case of solid tumour of kidney detected in the second trimester of pregnancy and managed by surgery in the postnatal period.

A 10-year-old Thai boy with a metanephric stromal tumor (MST) with unusual adipose differentiation is reported. It has been described that the heterologous tissue element including fat is exceptionally demonstrated in MST cases. Multifocal grossly detected intratumoral adipose tissue as shown in this present case has not been elucidated and illustrated before. The presence of the fatty component may perhaps make it difficult in distinguishing the MST from its differential diagnoses such as Wilms tumor metanephric adenofibroma, mixed epithelial stromal tumor, and lipomatous renal tumors including angiomyolipoma. The recognition of this rare entity is important and can prevent the patients from complications and unnecessary treatment.

A 44-year-old woman who underwent radical nephrectomy due to a left renal mass presented to our clinic. Results of the histopathological examination showed a mixed epithelial and stromal tumor of the kidney, a rare benign lesion of the kidney. The epidemiology, histopathological features, imaging features, possible pathogeneses, and treatment alternatives are discussed, and the relevant literature is reviewed. The postoperative course was uneventful, and the patient was free of local recurrence or metastasis until the last follow-up (12 months)., (Copyright © 2012. Published by Elsevier B.V.)

Congenital mesoblastic nephroma is a stromal neoplasm of infancy. It has been referred to as mesenchymal, cystic or leiomyomatous hamartoma. These tumors are centered around the hilus of the kidney. Mesoblastic nephromas need to be distinguished from other pediatric renal neoplasms as these lesions are treated by complete surgical excision without chemotherapy unless gross residual tumor remains. Here, we describe the gross and microscopic features of mesoblastic nephroma in a twenty-day old infant.

An 18-month-old male basset hound was presented with vomiting, diarrhoea and depression. Abdominal ultrasonography revealed a mass in the left kidney. An ultrasound-guided core-biopsy indicated aggregates of spindle cells, but did not allow a definitive diagnosis. Nephrectomy was performed after a period of six months, when ultrasound examination revealed a slight increase in mass dimensions. Histologically the mass was composed of neoplastic spindle cells forming interlacing fascicles, bundles and whorls, within a loose myxoid to dense collagenous stroma. Immunohistochemically neoplastic cells were positive for vimentin and smooth muscle actin. Based on these findings the tumour was diagnosed as a congenital mesoblastic nephroma, classical variant. After a two-and-a-half-year follow-up the dog was clinically healthy, indicating a benign behaviour. To the authors' knowledge, this report describes the first case of canine congenital mesoblastic nephroma successfully treated surgically, with a reasonable postsurgical follow-up., (© 2012 British Small Animal Veterinary Association.)

The congenital mesoblastic nephroma (CMN) described by Bolande et al. in 1967 is a renal tumor often discovered in neonatal period and early childhood. It's usually considered as a benign tumor with good prognostic for which nephrectomy is the reference treatment. But some cases of local recidives and metastatic sites had been described in the literature. For these reasons histologic analysis and quality of follow up are very important. In this observation we describe a neonatal kind of CMN and we discuss this pathology., (Copyright © 2011 Elsevier Masson SAS. All rights reserved.)

Background: Pediatric non-Wilms' renal tumors (NWRT) are poorly understood owing to their heterogeneity and relative rarity. This study aimed at auditing the outcome of the management of NWRT in a tertiary hospital in the Third World., Methods: Records of all patients (n = 68) treated for NWRT over a 32-year period (1978-2010) were reviewed retrospectively., Results: The major histological groups included clear cell sarcoma of the kidney (CCSK) (33.8%), mesoblastic nephroma (17.6%), cystic partially differentiated nephroblastoma (CPDN) (17.6%), intrarenal neuroblastoma (8.8%), malignant rhabdoid tumor (MRT) (7.4%), and renal cell carcinoma (RCC) (5.9%). Sixteen (69.7%) patients with CCSK and 11 (91.7%) with CPDN were aged 1-4 years. Ten (83.3%) patients with mesoblastic nephroma were aged <1 year and three (60.0%) with RCC were aged 10-14 years. Ten (43.5%) patients with CCSK and four (80.0%) with RCC had metastases at diagnosis. The sensitivity of a pretreatment Tru-Cut biopsy was 100% for MRT. All the patients with CCSK, mesoblastic nephroma, CPDN, and RCC had radical nephrectomy. Only eight (34.8%) patients with CCSK received radiotherapy. The overall 1-10-year survival rates were 52.2%, 91.7%, 75.0%, 40.0% and 0.0% for CCSK, mesoblastic nephroma, CPDN, RCC, and MRT, respectively. The overall 1-10-year survival for the entire cohort was 51.5%., Conclusions: The demography and clinical presentation of pediatric NWRT, which comprises 13.6% of pediatric renal tumors in the Third World, were similar to those in the Developed World. The overall 1-10-year survival for pediatric NWRT was low.

A 9-month-old boy underwent nephrectomy for a renal mass. Congenital mesoblastic nephroma was diagnosed, and the patient received postoperative chemotherapy. Tumor recurred 6 months later as a scrotal mass. After orchiectomy, diagnosis of metanephric stromal tumor (MST) was made; review of the nephrectomy specimens confirmed this diagnosis. No additional treatment was given, and the child is alive and well 31 months later. Taking into account the histopathological entity of MST in the differential diagnosis of stromal renal tumors in childhood can spare the patient further, potentially toxic, treatment even in the case of relapse, as reported here for the first time., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Background: Mesoblastic nephroma (MN) is a rare tumour which occurs mainly in early infancy and for which primary nephrectomy is the treatment of choice. This study aimed to assess surgical complications and outcomes in this patient group and to re-evaluate the age threshold of 6 months for recommending primary nephrectomy., Procedure: A retrospective file review of all cases of MN registered in UK Children's Cancer and Leukaemia Group renal tumour trials between October 1991 and March 2008. Data from the trials were compared with data held by the National Registry of Childhood Tumours, Oxford., Results: Forty-seven (3.5%) confirmed cases of MN were found among 1346 registered renal tumours. Median age at diagnosis was 30 days (range birth-3.8 years). MN was significantly more common in the first 3 months of life compared to between 3 and 6 months (33 vs. 2 cases). Seven cases occurred between 6 months and 1 year and only five cases occurred beyond 1 year of age. There was a significant difference in the age of diagnosis by histological subtype. There were 11 complications in the series; no registered patient developed a recurrent tumour; and all were alive at last follow-up., Conclusions: Outcome for children with MN is excellent at all ages, with little indication for adjuvant chemotherapy. Children presenting at <3 months of age, should be treated by primary nephrectomy. In those presenting aged >3 months, alternative diagnoses should be considered, especially in the presence of surgical risk factors., (Copyright © 2011 Wiley-Liss, Inc.)

Parathyroid hormone-related protein (PTHrP) mediated hypercalcemia of malignancy is rare in children, and even more so in the setting of a benign tumor. We report two infants with PTHrP-mediated hypercalcemia secondary to congenital mesoblastic nephroma and their outcome after removal of the benign tumor. Pre-operatively hypercalcemia was corrected with saline hydration, furosemide, calcitonin and/ or pamidronate. Following resection of the tumor serum PTHrP normalized. Immunohistochemical staining of tumor cells was positive for PTHrP. Post-operatively the infants developed elevated serum parathyroid hormone with low- normal serum Ca and P, and undetectable urinary Ca and P, probably due to their movement into bone. Children needed treatment with calcitriol, Ca and P supplementation for 6-12 weeks until PTH normalized and urinary Ca and P were detected, suggesting bone replenishment. We conclude that benign congenital mesoblastic nephroma can secrete PTHrP that can cause severe hypercalcemia; and following excision one should anticipate the development of a transient modified "hungry bone"-like condition requiring Ca, P and calcitriol therapy for several weeks accompanied by careful monitoring of mineral homeostasis.

Mixed epithelial and stromal tumor of the kidney is a newly categorized lesion, with few reported cases. We report a rare case of a 45-year-old woman with a palpable abdominal mass and elevated serum level of serum cancer antigen 125, who was not receiving hormones or contraceptive agents. Abdominal magnetic resonance imaging revealed a large multilocular cystic tumor that arose in the left central kidney. Nephrectomy was performed under the initial impression of cystic renal cell carcinoma; however, a diagnosis of mixed epithelial and stromal tumor was confirmed according to pathological and immunohistochemical findings. Serum level of cancer antigen 125 returned to normal after 1 month postoperatively and no recurrence was found in the following 18 months., (Copyright © 2011 Formosan Medical Association & Elsevier. Published by Elsevier B.V. All rights reserved.)

Cystic nephroma (CN) is a rare benign neoplasm of kidney with excellent prognosis. An accurate pre-operative diagnosis differentiating CN from other cystic renal malignancies may be impossible by clinical and radiological examination, and histopathological examination provides the final diagnosis. This report describes two adult patients with large multi-locular cystic renal masses on imaging and the diagnosis of CN was clinched post-operatively by the honeycomb appearance of the cut specimen and the finding of multiple, non-communicating fluid filled cysts lined by cuboidal or flattened epithelial cells and absence of blastemal cells on microscopy. Tumor diameter on cross sectional imaging remains the key parameter for treatment decisions in renal neoplasms, with nephrectomy being preferred for larger lesions.

Background: Renal tumors are rare in infants less than 6 months of age, being congenital mesoblastic nephroma the most frecuent in this age group. We reported 4 cases treated in our hospital in the last years., Methods: We analyze age, sex, the clinical presentation as well as diagnosis and treatment., Results: Range of age at diagnosis was 0-6 months. In our study the predominant sex was female. Clinical presentation was abdominal mass in all of cases with hypertension (HTA) in two of them. Scan ultrasound has been the method of dignostic, that was completed with Magnetic Resonance Imaging (MRI). The tretament was open surgery in three cases and laparoscopic on the last. All patients are alive with no evidence of disease., Conclusions: Low frecuency of this tumor limit the experience on diagnostic and treatment. Standard treatment is nephroureterectomy radical with free margins. Adjuvant therapy should be considered in recurrent disease although exists few studies. Laparoscopic surgery should be an alternative to clasical treatment since permits excision with good security margins.

The prenatal diagnosis of abdominal mass poses the problem of its origin. Renal tumors are rarer than neuroblastoma but they are most often congenital mesoblastic nephroma. The congenital mesoblastic nephroma has a good forecast in spite of a sonographic impressive aspect. MRI can help to locate tumor but cannot tell difference between the different kinds of renal tumor. Prenatal forecast is especially linked with hydramnios and hydrops fetalis. Histolological study of the tumor is important for the prognosis. Two morphological subtypes are currently distinguished: the classic type with a good forecast and the atypical or cellular type. Distant metastases have been related only to the cellular form but especially in infants aged more than 3 months and never in the newborns. The diagnosis of the tumor does not change the mode of delivery except in case of an important volume. Complications are searched during the first days of life: hypertension, hypercalcemia, vomiting, hyperreninemia. Radical nephrectomy is performed after the end of the first week. In case of a classic form, the healing is always obtained. In case of cellular form, distant metastases are searched. In any rate, the follow-up is recommended until the end of the growth.

Congenital mesoblastic nephroma (CMN) is a rare paediatric renal neoplasm. It is a diagnostic challenge to the pathologists due to its close differentials having ominous prognosis. We present three cases of CMN with unusual morphology including evidence of renal dysplasia in one of them.

The following is a report of the unusual case of a multilocular cystic nephroma in an 8-year-old boy who was transferred to our unit with a palpable abdominal tumor. The patient suffered from thoracic pain and night sweating. The laboratory values were normal. Abdominal sonography showed a huge kidney tumor on the right side consisting of numerous small cysts transversed by irregular septa of variable thickness. The cysts had a diameter of 1 -5 mm; larger cysts of more than 1 cm in diameter were not able to be shown. In the center of the tumor a normal renal parenchyma was able to be shown. The tumor arose like a mushroom from the kidney. Color Doppler sonography showed good vascularity of the normal renal parenchyma while the tumor had only a few internal vessels. The tumor was surgically removed. The histologic diagnosis was cystic nephroma. Unusual features of this tumor were the small size of the numerous cysts similar to polycystic kidney disease and the mushroom-like growth of the tumor.

Recently, various childhood tumors such as leukemia, neuroblastoma, hepatoblastoma, retinoblastoma, and central nervous system tumors in patients born after assisted conception have been reported. Although involvement of in vitro fertilization in the tumor pathogenesis was not established, the likely effect of assisted reproductive technology has been increasingly considered in these tumors in the last decade. Congenital mesoblastic nephroma is the most common renal tumor of infancy younger than 6 months associated with an overall good prognosis. The cellular variant of congenital mesoblastic nephroma, which occurs primarily in infants older than 3 months, confers a less favorable prognosis. We present a case of an atypical congenital mesoblastic nephroma with cellular elements in a 2-month-old infant who was born after in vitro fertilization. To our knowledge, this is the second congenital mesoblastic nephroma case and the first one with cellular variant reported to date in the English literature after a pregnancy induced by an assisted reproductive technology.

Wilms' Tumour (WT) is the most common kidney tumour in childhood, this fact and the embryonic complexity of WT create, whenever one of its three classical components predominates in cytologic smears, difficulties in the differential diagnoses with other less common entities. In the present study, we review the cytological and immunohistochemical characteristics of three children renal tumours, a Clear Cell Sarcoma of the Kidney (CCSK-case1), a Cellular Mesoblastic Nephroma (CMN-case2) and a Metanephric Adenoma (MA-case3) and compare them, for differential diagnostic purposes, with smears of blastematous, mesenchymal and epithelial predominant WTs, previously diagnosed in our Department. In all cases a mass was detected in the abdomen (2 and 8 year old children-cases 1 and 3, respectively), and pre-birth in case 2 (the tumour was detected during pregnancy). Fine needle biopsy was performed followed by routine cytologic examination. The presence of moderate amount of blue pale cytoplasm in neoplastic cells (case1), the presence of tightly cohesive, bland, spindle tumour cells (case2) and the identification of small, well differentiated epithelial tubules with psammoma bodies in case 3, were the main morphologic characteristics that we think represent the most important elements for distinguishing our cases from a WT. Immunoreactivity was only helpful in case 1 as we found a characteristic dot-like pattern positivity for vimentin, in the absence of immunoreactivity for the other markers that are usually positive in WT. Summing up, these three cases demonstrate that cytopathologists should be aware of the occurrence of uncommon renal neoplasms in childhood and should be acquainted with their characteristics, in order to avoid false diagnoses.

The authors present an atypical case of MEST uncovered in 12-year-old girl diagnosed with recurrent pyuria and persistent albuminuria with concomitant hypertension. Urine changes persisted despite the antibiotics therapy and they were accompanied with aseptic urine cultures. While investigating these changes, USG, urography, CT and MRI were performed and these manifested tumor-like change in the right kidney. Right-side nefrectomy was performed. Microscopically MEST was found while infection was found in parenchyma. Mixed epithelial and stromal tumor is a very rare kidney tumor that occurs almost exclusively in perimenopausal women or women after a long-term estrogen replacement. There are only few cases of this tumor in premenarcheal girls described in literature.

Congenital mesoblastic nephroma (CMN) is a rare tumour of infancy having an overall good prognosis. The less common, atypical CMNs have cellular elements in them and tend to have an unpredictable course. Occurrence in the perinatal period may further change the outcome. By reporting three patients presenting in the perinatal period with atypical CMN, an attempt is made in this paper to characterize the clinical behaviour of these variant tumours. Though one of our patients had an uneventful course, the other two had several complications including polyhydramnios, prematurity, hypertension, haemodynamic instability and tumour spillage. The course was complicated by recurrence in the latter two and refractoriness to chemotherapy and death in one. That the atypical subset of CMNs occurring in the perinatal period can have a stormy course is well illustrated by this report. Possible prognostic factors are evaluated and the sparse reports of similar cases in the literature are reviewed and compared.

The genetics of renal tumors in children is widely recognized. However, most of the studies published to date emphasize the association between Wilms tumor and the WT-1 gene. Recently, a unique translocation between the X chromosome and chromosome 1 or t(X;1) has been described in several reports of renal cell carcinomas (RCCs) diagnosed in children and adolescents that results in PRCC-TFE3 gene fusion. We report here a 9-year old African-American boy with a history of a right congenital mesoblastic nephroma treated with nephrectomy and followed by annual checkups. After 9 years, he was diagnosed with a mass at the hilum of the left kidney during the work-up of new-onset hypertension. A limited biopsy revealed densely hyalinized connective tissue that was initially interpreted to be a hyalinized contralateral mesoblastic nephroma. The child received chemotherapy, but the mass continued to grow. He underwent a left nephrectomy, and the pathology was diagnostic for a clear cell RCC. Chromosomal analysis disclosed a t(X;1)(p11.2;q21) translocation, which is known to result in a PRCC-TFE3 gene fusion. The tumor showed nuclear labeling for TFE3 protein by immunohistochemistry, supporting the above diagnosis. He has been on hemodialysis, is tumor free, and has not been receiving chemotherapy for 24 months. This is the first report of a RCC as a second malignant neoplasm in a child treated for a congenital mesoblastic nephroma.

Congenital mesoblastic nephroma (CMN) accounts for approximately 5% of paediatric renal tumours with the highest peak of incidence during the first 3 postnatal months. CMN almost always has a favourable prognosis. Therefore, CMN needs to be correctly diagnosed and differentiated, principally histologically, from other pediatric neoplasms. We present a clinicopathologic study of 5 cases of CMN.

A 51-year-old, perimenopausal, female patient with 1-month history of right flank pain who was diagnosed with a renal mass and underwent nephron-sparing partial nephrectomy is presented. The renal mass was found to be a benign, biphasic tumor composed of an epithelial component, consisting of ducts of variable size scattered within a mesenchymal component, composed of spindle cells arranged in sheets and fascicles. No atypia, mitosis, or necrosis was found. The spindle component shows desmin, smooth muscle actin, and estrogen and progesterone receptor positivity immunohistochemically. The diagnosis of benign mixed epithelial and stromal tumor of the kidney is rendered. No recurrent disease has been detected during 2 years of follow up.