Therapy and outcome in 51 children with mesoblastic nephroma: a report of the National Wilms' Tumor Study

A novel reciprocal translocation (14;15)(q11;q24) in a congenital mesoblastic nephroma

We describe a novel reciprocal translocation, t(14;15)(q11;q24), as the sole cytogenetic aberration in a congenital mesoblastic nephroma. The tumor was predominantly of "classic" morphology, but with small cellular islands of larger cells indicating early transformation to the cellular type. This is the first report of a reciprocal translocation as the sole anomaly in a congenital mesoblastic nephroma.

The presence of hydrops fetalis in a fetus with congenital mesoblastic nephroma

We report the first prenatal diagnosis of a case of congenital mesoblastic nephroma complicated by hydrops fetalis. Congenital mesoblastic nephroma is generally thought to be a benign disease but when complicated by hydrops fetalis it may be a potentially lethal condition.

Preoperative chemotherapy for mesoblastic nephroma

A neonate with extensive stage III mesoblastic nephroma was confirmed at operation to have a tumor that was too infiltrative and too advanced for primary excision. The abdomen was closed after multiple biopsies. Vincristine (1.1 mg/m2) was given intravenously once a week for a total of eight doses. Repeat CT scan confirmed shrinkage of the tumor and a nephrectomy could be performed safely and the tumor removed at the second laparotomy. CT scan repeated 1 year later showed no recurrence. This case illustrates the effective use of a single drug pre-excision chemotherapy which allowed a nephrectomy for extensive stage III mesoblastic nephroma to be carried out safely.

Congenital mesoblastic nephroma presenting with hemoperitoneum and shock

We describe an unusual presentation of a congenital mesoblastic nephroma in a 5-month-old boy. He was in hemodynamic shock in admission. Sonography revealed an echogenic right kidney and hemoperitoneum. Right nephrectomy was performed, and he is well one year later without any further treatment.

A further diagnostic test in neonatal/infant solid renal mass: two cases of mesoblastic nephroma showing uptake of Tc99mDMSA

During the first 6 months of life, mesoblastic nephroma is the most common cause for a solid renal tumour. We describe two cases showing uptake of Tc99mDMSA by mesoblastic nephroma. Tc99mDMSA scanning may suggest the correct diagnosis and so allow nephrectomy without biopsy, rendering the latter unnecessary in mesoblastic nephroma.

Mesoblastic nephroma metastatic to the lungs and heart--another face of this peculiar lesion: case report and review of the literature

A case of mesoblastic nephroma in a 14-month-old girl who developed consecutive metastases in the lung and the heart is presented. This tumor is considered to be benign and cured by surgery only. Recurrent cases are extremely rare and usually related to unclear surgical margins. Metastatic mesoblastic nephroma has been previously described in only two cases. The present case highlights a new, previously undescribed feature--the ability to metastasize to sites other than lung.

Position paper: imaging methods for primary renal tumors of childhood: costs versus benefits

The patterns of disease distribution at diagnosis and during follow-up were cataloged for the primary renal tumors of childhood. These data, derived from more than 1,500 patients, were used to define the most rewarding and cost-effective imaging methods required for patient management. The basic information needed prior to surgery includes whether there is a functioning kidney on the opposite side, and whether there are lung metastases or inferior vena cava thrombi. Simple X-ray examinations and ultrasonography (US) will provide the necessary data. Postoperatively, when the histology is known, examination of the brain (MRI or CT scan) is needed for patients with the rhabdoid tumor and clear cell sarcoma of the kidney (CCSK) who are prone to develop brain lesions; and the skeletal system (bone scan, X-ray skeletal survey) for CCSK and for renal cell carcinoma patients who tend to develop bone metastases. Continuing examination of the lung (chest films) is required for all histologies except perhaps for mesoblastic nephroma, which seldom metastasizes. The opposite kidney needs follow-up (US) for 5 or more years to exclude metachronous involvement if nephrogenic rests are present in either kidney. Sophisticated imaging studies, which cost five times or more than simple X-ray examinations or US, are not warranted routinely, and should be reserved for those cases where simpler, less expensive studies do not suffice for reaching patient management decisions.

Molecular characterization of congenital mesoblastic nephroma and its distinction from Wilms tumor

BACKGROUND

Congenital mesoblastic nephroma (CMN) is a rare tumor of the neonatal kidney. It was once thought to be a variant of Wilms tumor that also arises from primitive renal cells.

METHODS

Molecular characteristics of two CMN were studied to clarify their potential relationship to Wilms tumors. Patterns of gene expression were assayed by Northern blot hybridization analysis. Tumors were tested for loss of heterozygosity (LOH) at chromosomes 11p13 and 11p15 using Southern blot analysis.

RESULTS

The CMN, like Wilms tumors, demonstrated high-level expression of insulin-like growth factor II. Unlike Wilms tumors, however, the CMN expressed neither the N-myc oncogene nor the putative Wilms tumor suppressor gene, WT1. Using a panel of probes spanning 11p13 and 11p15, no LOH was detected in the CMN, nor was there evidence of deletion or rearrangements of WT1.

CONCLUSIONS

Although Wilms tumor and CMN both arise from the developing kidney, molecular characterization suggests that different factors are involved in the pathogenesis of these two tumors.

Nucleolar organizer regions in congenital mesoblastic nephroma

A review of 78 renal tumors in patients under 6 months of age revealed 35 congenital mesoblastic nephromas (CMNs). Based on cellular criteria, 14 were classified as classical, 4 as partly cellular, and 17 as cellular CMN. The mean ages were 24, 11, and 70 days, respectively. There were 13 intrarenal tumors (stage I) but 9 classical, 3 partly cellular, and 5 cellular CMNs extended to the perirenal fat (stage II) and 5 cellular tumors ruptured (stage III). In order to assess cellular proliferative activity, silver staining of nucleolar organizer region (Ag-NOR) proteins was performed on 19 CMNs. The number of Ag-NOR dots per cell was significantly lower in classical and partly cellular CMN than in cellular CMN, whatever the stage (P < .01). Within the cellular CMNs, the mean number of Ag-NOR dots was statistically higher in the single case that recurred with fatal outcome (P < .02). Counting of Ag-NOR dots appears to be a reproducible method for evaluating the biologic potential of CMNs. The number of Ag-NOR dots, DNA content measurements, the histological subclassification, and the presence or absence of tumor at the surgical margins may be useful features in selecting those patients who will benefit from further treatment after nephrectomy.

Preoperative chemotherapy of cellular congenital mesoblastic nephroma in a 5-month-old infant

Cellular (or atypical) congenital mesoblastic nephroma (CMN) is a potentially aggressive form of the benign classical congenital mesoblastic nephroma. We report here a case of cellular CMN in a 5-month-old boy treated preoperatively with chemotherapy with an excellent response allowing a complete surgical resection.

renal tumors and tumor-like lesions in pediatric patients

Renal enlargement presenting as an abdominal mass(es) is attended by a lengthly differential diagnosis of non-neoplastic and neoplastic lesions with a range in serious connotations and consequences. Simple compensatory hypertrophy and unilateral multicystic dysplasia are relatively innocuous and easily recognized with appropriate imaging studies; they are also related in the sense that the normal contralateral kidney hypertrophies in the absence of a non-functioning dysplastic kidney. Bilateral nephromegaly in a neonate is generally a sign of autosomal recessive polycystic kidney disease or multicystic dysplasia secondary to distal obstructive uropathy. Primary neoplasms of kidney in the pediatric population in the past were traditionally classified as Wilms' tumors, but that erroneous practice has been eliminated with the recognition of several distinctive neoplasms in addition to classic Wilms' tumor. Separating a typical Wilms' tumor from mesoblastic nephroma, clear cell sarcoma of the kidney and the malignant rhabdoid tumor, for treatment and prognostic purposes, has become the accepted norm in the past 12-13 years. Another important advance at the cellular level is the recognition of a deletion in the short arm of chromosome 11 in the cultured cells of Wilms' tumor and in the germ cell line in certain clinical settings of Wilms' tumors. A dramatic expansion in the understanding and management of childhood renal neoplasms has occurred through the multimodality approach of laboratory investigation and applied clinical research.

Preoperative care of infants with nephroblastoma. The International Society of Pediatric Oncology 6 experience

The International Society of Pediatric Oncology (SIOP) recommends preoperative treatment in the management of eligible patients with Wilms' tumor. Until 1980, children younger than 12 months of age (infants) at diagnosis had been excluded from the SIOP trials. SIOP 6, conducted from 1980 to 1987, was the first SIOP study to include infants older than 6 months of age. This retrospective analysis of 145 infants registered to SIOP 6 demonstrates that in infants older than 6 months and having favorable histology (FH), a two-drug preoperative chemotherapy (CT) regimen of 4 weeks significantly ameliorated stage distribution as determined at delayed surgery but did not affect a good outcome. However, the CT dose utilized in SIOP 6 resulted in an unacceptable toxicity in this age group, and SIOP 9, the new SIOP study of Wilms' tumor, recommends a reduced dose of CT in infants. Preoperative CT is not recommended in infants younger than 6 months of age. Specifically, the high incidence (29%) of mesoblastic nephroma in this age group does not justify such an approach. Histopathologic diagnosis should be obtained in these patients before any treatment.

Congenital cystic mesoblastic nephroma: a rare cystic renal tumour of childhood. Case report

A 3-month-old baby boy presented with a right-sided abdominal mass that was shown on radiographic and ultrasonographic examination to be cystic and within the kidney. Histological examination of the right nephrectomy specimen showed it to be a congenital cystic mesoblastic nephroma. The patient made an uneventful recovery and there were no signs of recurrence eight years later. Though this tumour is extremely rare it should be considered as a differential diagnosis in infancy as its prognosis and treatment are different from those of other tumours.

Congenital mesoblastic nephroma, nephrocalcinosis, and hypertrophic pyloric stenosis

A cellular variant of congenital mesoblastic nephroma (CMN) occurring in a newborn is presented. Coincidental findings were congenital hypertrophic pyloric stenosis (CHPS) and nephrocalcinotic hypercalcemia that reverted after nephrectomy. As of the day of writing, this multiple association has not been reported. The authors believe that both CMN and CHPS could be interpreted as fibroblastic proliferative-related entities. Transient hypercalcemia seems to be a paraneoplastic phenomenon.

Congenital mesoblastic nephroma: possible prognostic and management value of assessing DNA content

The case records and pathology of all children with kidney tumours treated in the West Midlands Health Authority Region (WMHAR) from 1957 to 1986 were reviewed. The histology was reviewed by a panel of three paediatric pathologists. Thirteen (6%) out of 211 cases were considered to have congenital mesoblastic nephroma (CMN). Nine were of the conventional type, three of the atypical cellular type, and one mixed. DNA ploidy was investigated and showed two of the tumours to be aneuploid and nine diploid (tissue was not available in the two other cases). The two aneuploid tumours were of atypical cellular and mixed histology, respectively; the diploid tumours were of the conventional type in eight cases and atypical cellular in one. The atypical cellular type has been reported to behave more aggressively, but the benefit of additional treatment after surgery to prevent recurrence remains unclear. Measurement of DNA content by flow cytometry, together with histological subclassification, may be useful in selecting patients who will benefit from further treatment after surgery.

Congenital mesoblastic nephroma occurring in a solitary kidney

Congenital mesoblastic nephroma (CMN) is a rare tumour arising in early infancy. This is the first reported case of CMN arising in a solitary kidney. The literature and radiological features of CMN are reviewed.

Cellular congenital mesoblastic nephroma: what are the options

Cellular congenital mesoblastic nephroma is a potentially aggressive variant of the usually benign congenital mesoblastic nephroma. Our recent experience with 3 patients with cellular congenital mesoblastic nephroma prompted a critical review of the literature to evaluate risk factors for recurrence and present treatment programs. A total of 38 patients, including our 3 patients, with cellular congenital mesoblastic nephroma were divided into 2 groups: those with recurrent (7) and those with nonrecurrent (31) tumors. A statistical comparison of clinical and pathological data was performed. Of the 7 patients with local recurrence and/or pulmonary metastasis, 3 died. The average time to first recurrence was 5.4 months. Histological differences were not predictive of recurrent disease. Pathologically positive surgical margins (p less than or equal to 0.02) were the only statistically significant variable suggesting recurrent disease. While the presenting age was not predictive of recurrence (p equals 0.27), the relative risk of recurrence doubles in the first 3 months of life and quadruples after 6 months of life. Treatment programs also were evaluated. An infant with cellular congenital mesoblastic nephroma, regardless of age, is cured with surgery alone given clear pathological margins. In 4 of 5 children with recurrent tumors Wilms tumor treatment agents (vincristine and actinomycin D) failed to control local or distant disease. Of these cases 2 subsequently were treated with sarcomatous chemotherapy (vincristine, cyclophosphamide and doxorubicin) and both are in remission. These agents may prove to be more efficacious in the treatment of local or metastatic disease.

Classical and cellular (atypical) congenital mesoblastic nephroma: a clinicopathologic, ultrastructural, immunohistochemical, and flow cytometric study

Sixteen cases of congenital mesoblastic nephroma (CMN) were studied. The tumors showed variable patterns of growth, degrees of cellularity, and mitotic activity. Six tumors had the classical pattern of CMN, seven were of the cellular or atypical variant and three showed combined features. The mean ages at presentation were 16 days, 5.3 months, and 2.3 months, respectively. Average size and weight were 5.1 cm and 94 g for classical CMN, 9.1 cm and 620 g for cellular CMN and 10.5 cm and 150 g for combined tumors. Cyst formation, hemorrhage and necrosis were confined to cellular CMNs and to cellular areas of combined CMNs. Mitotic activity ranged from 0 to 1/10 high-power fields (HPFs) in classical tumors to 25 to 30/10 HPFs in cellular tumors. Clear cell sarcoma-like areas were observed in three neoplasms. In ten cases there was invasion of perirenal fat; in one case each, invasion of the psoas muscle, renal vein wall, and renal vein lumen was observed. Ultrastructural and immunohistochemical studies showed features consistent with myofibroblastic differentiation. Flow cytometric analysis revealed euploidy in one classic CMN, one cellular CMN and in classic areas of a combined CMN; cellular areas of the latter tumor were aneuploid. All patients with follow-up were alive without evidence of disease after a mean period of 5 years following nephrectomy alone. No correlation was observed between the pathologic features assessed and the biologic behavior of these neoplasms.

Congenital mesoblastic nephroma, renin production, and hypertension

Between 1964 and 1987, 12 patients with mesoblastic nephroma were treated. The BP was measured preoperatively in five patients, four of whom were hypertensive. Following nephrectomy, the BP returned to normal. Plasma renin levels were measured in one patient; they were markedly elevated pre-operatively, but returned to normal following tumour excision. Immunoreactive renin staining, using a polyclonal antibody to human renin, was performed in the 12 patients. Staining was positive in ten patients. The most intense staining was noted in the areas of cortex entrapped within the tumour, and in perivascular spaces not associated with entrapped cortex. These findings suggest that hypertension secondary to increased tumour associated renin production is a feature of congenital mesoblastic nephroma.

A mesoblastic nephroma with hypercalcaemia

A 14 week old female infant who presented with a mesoblastic nephroma was found to be hypercalcaemic. This was corrected prior to removal of the tumour and serum calcium concentrations remained within the normal range postoperatively. Hypercalcaemia is a life threatening complication of mesoblastic nephromas and should be investigated in all cases.

Selecting initial therapy for pediatric genitourinary cancers

A few decades ago, there were few choices in the initial management of children with genitourinary tumors. Radical surgical removal was the only line of attack that promised any chance of survival. Improvement in the results of multimodal therapy in the last 15 years have radically altered the outlook for these children, hence the choice of therapy. As with other childhood cancers, the choice of therapy is based on risk-benefit evaluations of the roles of surgery, irradiation, and chemotherapy, since all three modalities have their associated morbidities. Current emphases are on preservation of function without compromising cure. The large cooperative clinical trials have emphasized this aspect of pediatric oncology. They have demonstrated, for example, that radiation therapy can be omitted from primary management of early stage Wilms' tumor patients who are given adequate adjuvant chemotherapy as can both radiation therapy and ablative surgery in certain cases of early stage rhabdomyosarcoma. Routine retroperitoneal node dissections have been shown to be of dubious diagnostic or therapeutic value in boys with testicular cancers. The need for bilateral oophorectomy in girls with dysgerminoma can similarly be questioned. Choices of initial therapy, therefore, are not static. They are becoming wider with each advance in multimodal therapy. Clinicians must keep abreast of the results of clinical trials so they can offer their patients the combination of treatments that will preserve function, and produce the smallest number of late complications without jeopardizing survival chances.

Congenital mesoblastic nephroma: a clinicoradiologic study of 17 cases representing the pathologic spectrum of the disease

Congenital mesoblastic nephroma (CMN) is a rare infantile renal tumor with a generally excellent prognosis. We describe 17 tumors that fit into the pathologic spectrum of CMN proposed by Beckwith, which ranges from benign renal tumors, through atypical "gray zone" lesions of more aggressive potential, to "crossover" tumors akin to clear cell sarcoma of kidney. Nine patients with histologically typical CMN were significantly younger and had smaller tumors than did eight patients with atypical CMN. Clinical features did not differ in the two groups of patients. A distinctive "ring sign" on renal sonography was commonly seen in patients with typical intrarenal CMN. All 17 patients were alive with no evidence of disease at a mean follow-up of 10 years. Nephrectomy was adequate therapy for younger infants and for those with typical CMN. Nephrectomy was probably also adequate therapy for infants 3 months of age or younger with atypical CMN, even if the tumor extended to the surgical resection margins and into the perinephric connective tissues. Adjuvant chemotherapy or radiation or both should be reserved for patients older than 3 months who have grossly unresected tumors and for those patients whose tumors have an unequivocally malignant histologic appearance or evidence of aggressive biologic behavior.

Advances in the care of the child with cancer. The importance of histologic subclassification of tumors

The importance of histologic subclassification of tumors lies principally in the correlation between nosology and tumor biology, including response to therapy. Subclassifications that are practically achieved, reproducible and uniquely predictive are of great value. As new methods are engaged and new clinical data are reported, classifications may be changed. Subclassifications of solid tumors with proven therapeutic application are exemplified by renal tumors and lymphomas that are commonly referred to as "favorable" or "unfavorable histology." Subclassification of soft tissue sarcomas, neuroblastoma and tumors of the central nervous system are being investigated, but are presently of undetermined relevance. Classifications and subclassifications of solid tumors of children are presented in the context of prognostic relevance.

Wilms' tumor in the neonate: a report from the National Wilms' Tumor Study

Renal neoplasms in the neonate are quite uncommon. Twenty-seven of the 3,340 patients (0.8%) registered on the National Wilms' Tumor Studies from 1969 through April 1984, were 30 days old or less. Of these 27 patients, 18 had mesoblastic nephroma, 1 had a malignant rhabdoid tumor of the kidney, and 4 others had nonneoplastic lesions. The remaining four infants were reviewed in detail. All had favorable histology Wilms' tumors; none had distant metastasis at diagnosis. Treatment ranged from surgery alone to excision plus three-drug therapy for 15 months. All fared well. The patient with Stage I rhabdoid tumor died at eight weeks of age in spite of aggressive four-drug therapy. This review supports the view that Wilms' tumor in the neonate is extremely rare.

Hypercalcemia in association with mesoblastic nephroma: report of a case and review of the literature

Hypercalcemia, often associated with certain types of adult tumors, has also been described in pediatric neoplasms. In childhood, the more common associations include lymphoma, leukemia, rhabdomyosarcoma and rarely neuroblastoma. However, recently, several infants with hypercalcemia were described having renal tumors without bone metastases. The following is a case report of a 2-month-old infant who presented with severe hypercalcemia and a large right-sided abdominal mass, which at surgery was diagnosed as a cellular mesoblastic nephroma.

Calcification and ossification in a congenital mesoblastic nephroma

Calcification is uncommon in any of the intrarenal tumors of childhood. A 6-month-old girl with multiple dense intrarenal calcifications was found to have congenital mesoblastic nephroma.

Mesoblastic nephromas: a study of 29 tumours from the SIOP nephroblastoma file

In a series of 889 Wilms' tumours we found 29 pure mesoblastic nephromas. The age of the patients varied from newborn to 22 months, but only five were older than four months. Two histologic types were recognized--leiomyomatous (9) and cellular (20) with a fibrohistiocytic appearance. The leiomyomatous type was almost invariably in stage I, smaller and present in younger infants. At operation half of the cellular type has ruptured or infiltrated the renal pelvis or perirenal tissue. Two patients died of postoperative complications. All others are alive after four years and free from disease.

Developmental cystic renal neoplasms in children. Diagnostic imaging characteristics

We report diagnostic imaging and histopathologic findings in four children with different cystic renal neoplasms. The features discerned with computed tomography (CT), as well as ultrasound, correlated well with gross histologic findings, although a definitive diagnosis could not be made on the basis of CT and ultrasound alone. Because the most malignant variants of these lesions cannot be excluded preoperatively, we advocate complete diagnostic imaging studies, followed by nephrectomy, for all cases of cystic renal neoplasms in infants and children.