Cystic partially differentiated nephroblastoma: a clinicopathologic entity in the spectrum of infantile renal neoplasia

Development of renal adenocarcinoma in a ferret with renal cortical cysts (Mustela putorius furo)

CASE DESCRIPTION

A 5.5-year-old 0.929-kg spayed female domestic ferret (Mustela putorius furo) underwent serial abdominal ultrasonographic and clinicopathologic examinations after multiple renal cysts were detected bilaterally during a routine examination.

CLINICAL FINDINGS

The ferret was apparently healthy at the start of the monitoring period and had no clinical signs for > 20 months. Four months after the initial examination, the largest cyst became increasingly mineralized; 17 months after detection, it had increased in size and become amorphous, and the ferret's plasma BUN concentration was mildly high. Within 21 months after the first visit, a nodule was detectable, and hydronephrosis developed in the kidney with the largest cyst. Findings for fine-needle aspirates from the nodule were consistent with renal carcinoma.

TREATMENT AND OUTCOME

Contrast-enhanced CT revealed severe unilateral nephromegaly with no contrast uptake in the affected ureter. Following surgical removal of the affected kidney, histologic examination identified renal adenocarcinoma replacing the entire renal cortex and medulla. The ferret was euthanized postoperatively because of declining condition. On necropsy, metastasis to a mesenteric lymph node was identified; comorbidities included 2 other neoplasms and acute, severe injury of the contralateral kidney.

CLINICAL RELEVANCE

Neoplastic transformation of a renal cyst was suspected in the ferret of this report on the basis of observed ultrasonographic changes over time and extensive infiltration of the neoplasm throughout the affected kidney. Renal cysts are linked to renal neoplasia in other species, and the findings for this patient supported the need for periodic monitoring of renal cysts in ferrets.

Cystic partially differentiated nephroblastoma: a rare pediatric renal tumor-case report

Cystic partially differentiated nephroblastoma is a rare renal tumor of childhood. It is part of a spectrum of multicystic renal tumors that also includes cystic nephroma and cystic Wilms’ tumor. We present a case of cystic partially differentiated nephroblastoma, highlighting the clinical and imaging diagnostic challenge. Although the histological diagnostic criteria for all these 3 entities are well established, they are clinically and radiologically indistinguishable. Cystic partially differentiated nephroblastoma is often observed in male children under 2 years old. Typical clinical presentations include abdominal masses, abdominal pain and/or hematuria. Patients should be treated according to tumor histology and stage.

An organoid biobank for childhood kidney cancers that captures disease and tissue heterogeneity

Kidney tumours are among the most common solid tumours in children, comprising distinct subtypes differing in many aspects, including cell-of-origin, genetics, and pathology. Pre-clinical cell models capturing the disease heterogeneity are currently lacking. Here, we describe the first paediatric cancer organoid biobank. It contains tumour and matching normal kidney organoids from over 50 children with different subtypes of kidney cancer, including Wilms tumours, malignant rhabdoid tumours, renal cell carcinomas, and congenital mesoblastic nephromas. Paediatric kidney tumour organoids retain key properties of native tumours, useful for revealing patient-specific drug sensitivities. Using single cell RNA-sequencing and high resolution 3D imaging, we further demonstrate that organoid cultures derived from Wilms tumours consist of multiple different cell types, including epithelial, stromal and blastemal-like cells. Our organoid biobank captures the heterogeneity of paediatric kidney tumours, providing a representative collection of well-characterised models for basic cancer research, drug-screening and personalised medicine.

Pre-clinical cell culture models capturing the heterogeneity of childhood kidney tumours are limited. Here, the authors establish and characterise an organoid biobank of tumour and matched normal organoid cultures from over 50 children with different subtypes of kidney cancer.

DICER1 mutations in childhood cystic nephroma and its relationship to DICER1-renal sarcoma

The pathogenesis of cystic nephroma of the kidney has interested pathologists for over 50 years. Emerging from its initial designation as a type of unilateral multilocular cyst, cystic nephroma has been considered as either a developmental abnormality or a neoplasm or both. Many have viewed cystic nephroma as the benign end of the pathologic spectrum with cystic partially differentiated nephroblastoma and Wilms tumor, whereas others have considered it a mixed epithelial and stromal tumor. We hypothesize that cystic nephroma, like the pleuropulmonary blastoma in the lung, represents a spectrum of abnormal renal organogenesis with risk for malignant transformation. Here we studied DICER1 mutations in a cohort of 20 cystic nephromas and 6 cystic partially differentiated nephroblastomas, selected independently of a familial association with pleuropulmonary blastoma and describe four cases of sarcoma arising in cystic nephroma, which have a similarity to the solid areas of type II or III pleuropulmonary blastoma. The genetic analyses presented here confirm that DICER1 mutations are the major genetic event in the development of cystic nephroma. Further, cystic nephroma and pleuropulmonary blastoma have similar DICER1 loss of function and 'hotspot' missense mutation rates, which involve specific amino acids in the RNase IIIb domain. We propose an alternative pathway with the genetic pathogenesis of cystic nephroma and DICER1-renal sarcoma paralleling that of type I to type II/III malignant progression of pleuropulmonary blastoma.

Cystic nephroma and mixed epithelial and stromal tumour of the kidney: opposite ends of the spectrum of the same entity?

OBJECTIVES

The term "renal epithelial and stromal tumour" (REST) was proposed recently to encompass the spectrum of findings observed in cystic nephroma (CN) and mixed epithelial and stromal tumour (MEST) of the kidney. Our aim was to review the broad spectrum of usual and unusual clinical and morphologic findings observed in CN and MEST.

METHODS

Based on Medline database searches, all aspects of CN and MEST were assessed.

RESULTS

CN and MEST have a remarkable similarity in sex predilection, age distribution, and morphologic attributes of both the epithelial and stromal components and immunohistochemical profile, albeit with variation in individual categories, with higher prevalence of stromal-to-epithelial ratio, prominent ovarian-like stroma, smaller cysts, and stromal luteinisation in MEST, and large cysts, thin septa, and low stromal-to-epithelial ratio in CN. The stromal component in both lesions expresses estrogen and progesterone receptors. Rare and unusual morphologic features, such as endometrioid, cervical, and intestinal differentiation, and luteinised ovarian-like stroma, have been described in MEST. The epithelial element occasionally shows estrogen and progesterone receptors. Rare aggressive behaviour has been reported for both neoplasms.

CONCLUSIONS

Considerable overlap is apparent between the two lesions, which suggests that they may represent opposite ends of the spectrum of the same process. Even though an aggressive behaviour has been reported in very few cases, in general both neoplasms are considered benign and surgical excision is curative.

Treatment of cystic nephroma and cystic partially differentiated nephroblastoma--a report from the SIOP/GPOH study group

PURPOSE

Cystic partially differentiated nephroblastoma is a rare variant of Wilms tumor, and might be confused with cystic nephroma. Definitive diagnosis can only be made by histological examination. Therefore, initiation of therapy, either primary nephrectomy or preoperative chemotherapy, might create a dilemma when radiological diagnosis is doubtful.

MATERIALS AND METHODS

To define treatment strategies for these entities, we reviewed the records of 1,245 patients enrolled in SIOP (International Society of Pediatric Oncology) trials 93-01 and 2001 GPOH (German Society of Pediatric Oncology and Hematology) between July 1993 and August 2004. Data were collected retrospectively. Therapy, outcome and preoperative management were evaluated. To confirm diagnosis of cystic nephroma/partially differentiated nephroblastoma, all patients underwent review by the Reference Pathology Center of SIOP/GPOH.

RESULTS

A total of 14 patients with diagnoses of cystic nephroma (7) and cystic partially differentiated nephroblastoma (7) were identified. Median patient age at diagnosis was 1 year (0.46 to 3). Two patients received preoperative chemotherapy. Primary nephrectomy was performed in 12 patients. Two patients underwent partial nephrectomy. In 1 child postoperative chemotherapy was administered. None of the patients had progression of disease or recurrence. Overall survival was 100%. Median followup was 2.41 years (0.3 to 9).

CONCLUSIONS

In cystic renal tumors radiological findings should always be reviewed by the reference radiologist of the treatment protocol study group. Irrespective of the chosen therapy, outcome of cystic nephroma and cystic partially differentiated nephroblastoma is favorable. Even in large international trials the number of patients with cystic nephroma or cystic partially differentiated nephroblastoma is too small for statistical analysis.

Cystic partially differentiated nephroblastoma

Cystic partially differentiated nephroblastoma is a relatively rare tumour of the kidney usually affecting infants. Cystic Wilms' tumour and multilocular cystic nephroma should be distinguished from cystic partially differentiated nephroblastoma. Multilocular cystic nephroma is a benign tumour whereas cystic Wilms' tumour is at the malignant end of the range of classification of such tumours. Cystic partially differentiated nephroblastoma may undergo local recurrence but there is no report of metastasis.

Nephroblastic Neoplasms

Nephroblastoma, or Wilms tumor, is a malignant embryonal neoplasm that is derived from nephrogenic blastemal cells, with variable recapitulation of renal embryogenesis. The pathogenesis of nephroblastoma is complex and has been linked to alterations of several genomic loci, including WT1, WT2, FWT1, and FWT2. Generally, nephroblastoma is composed of variable proportions of blastema, epithelium, and stroma, each of which may exhibit a wide spectrum of morphologic variations. Distinguishing nephroblastoma with favorable histology from tumors that exhibit anaplasia is an integral component of histologic assessment because of its prognostic and therapeutic implications. Nephrogenic rests and a special variant of nephroblastoma, cystic partially differentiated nephroblastoma, also are discussed.

Cystic Tumors of the Kidney. Revision of the Literature and Authors'Cases

The authors report the clinico-pathological features of the so-called “cystic tumors of the kidney”, discussing data of the English literature and providing grossly and histologically illustrations. The following tumor entities will be discussed in detail: “cystic multilocular renal cell carcinoma”, “cystic nephroma”, “cystic partially differentiated nephroblastoma” and mixed (benign or malignant) epithelial/stromal tumor. The awareness of these clinico-pathologic entities by Urologist is important to assure patient a correct treatment and prognostic informations.

Renal cystic neoplasms and renal neoplasms associated with cystic renal diseases: pathogenetic and molecular links

Cystic renal neoplasms represent an isolated cystic mass not accompanied by cystic change of the renal parenchyma. Although cystic change may be seen in any type of renal neoplasm, a few (i.e., cystic renal cell carcinoma, cystic nephroma, cystic partially differentiated nephroblastoma, mixed epithelial and stromal tumor) are characterized by constant cystic change that may involve the entire tumor. Cystic kidney disease is characterized by cystic change, which usually involves the kidneys in a bilateral and diffuse pattern, does not create a discreet mass, and is due to hereditary or developmental conditions. Some of the cystic kidney diseases are not known to give rise to renal neoplasm; others such as autosomal polycystic kidney disease or multicystic dysplastic kidney may fortuitously coexist with renal neoplasms. Three conditions (acquired cystic kidney disease, tuberous sclerosis, and von Hippel-Lindau disease) are associated with renal neoplasms with such a high frequency that they are considered preneoplastic. This article reviews the differential diagnoses among cystic neoplasms. It also focuses on the underlying genetic and molecular mechanisms for the relationship between cystic renal diseases and renal neoplasms.

Association of cystic nephroma with angiomyolipoma in the same kidney

The synchronous occurrence of two different renal tumors in a patient is a rare event. Here we report an incidentally discovered coexistence of cystic nephroma with angiomyolipoma in the right kidney. The patient was a 68-year-old woman without the tuberous sclerosis complex. To the best of our knowledge, this combination of neoplasms has not yet been described before. This rare situation emphasizes the need for careful diagnosis and the correct management of coincident renal neoplasms.

Partial nephrectomy in cystic partially differentiated nephroblastoma

Cystic partially differentiated nephroblastoma (CPDN) is an uncommon renal neoplasm in children. It is now recognized as a tumor with low but definite malignant potential. The authors report a patient that was treated with partial nephrectomy and chemotherapy with successful outcome. The literature on CPDN is briefly discussed.

Cystic partially differentiated nephroblastoma in an adult: an immunohistochemical, lectin histochemical and ultrastructural study

AIMS

Cystic partially differentiated nephroblastoma (CPDN) is an uncommon renal multicystic tumour, usually affecting early infants. To our knowledge, this report describes the first case of CPDN occurring in an adult.

METHODS AND RESULTS

A 45-year-old man was found incidentally to have a left renal cystic tumour, measuring 20 mm in diameter, at the lower pole far from the pelvis. The tumour was composed of multilocular cystic spaces of variable size and intervening septa without solid nodular areas. The cysts were lined by a single layer of flattened, hobnail, or columnar epithelium. The septa were made of mesenchymal cells, which were admixed with small numbers of loosely aggregated blastemal cells, occasional tubular structures in various stages of development, and a few glomeruloid structures. The tumour cells had no anaplasia, and mitoses were rare. Immunohistochemical and lectin histochemical studies revealed that the cyst lining epithelium and the tubular structures in the septa expressed predominantly the markers for distal tubules and collecting ducts. Ultrastructurally, the cyst lining cells closely resembled collecting duct cells while some tubular structures showed an immature nephrogenic morphology. The patient was alive and well without evidence of recurrence 11 months after surgery.

CONCLUSIONS

CPDN does occur in adults, as experienced in Wilms' tumour, though its incidence is extremely low. This study suggests that CPDN may show maturation intermediate between cystic nephroma and Wilms' tumour, even in adult cases.

Partial nephrectomy in a cystic partially differentiated nephroblastoma

Cystic partially differentiated nephroblastoma (CPDN) is a rare neoplastic disorder consisting of a well-demarcated cystic lesion of the kidney where blastemal or other embryonic cells are present in the septa of the cysts. Magnetic resonance imaging can detect the cystic character of the lesion and will produce imaging features that are highly suggestive of either CPDN or cystic nephroma (CN) (synonym: multilocular cyst of the kidney), a benign entity. Although malignant potential exists in CPDN, all cases reported to date have had a favorable prognosis after surgery alone. Partial nephrectomy is considered safe, and the treatment of choice in the newborn period. We report a case of CPDN in a newborn that was successfully treated with partial nephrectomy. More than five years after nephron sparing surgery, the involved kidney shows normal anatomical structure except for a diminished upper pole, no evidence of tumor recurrence and good renal function.

Deletion of WT1 and WIT1 genes and loss of heterozygosity on chromosome 11p in Wilms tumors in Japan

Six of 39 sporadic Wilms tumors had gross homozygous or hemizygous WT1 and WIT1 deletions. Two Wilms tumor-aniridia-genitourinary abnormalities-mental retardation syndrome patients had total hemizygous WT1 and WIT1 deletions in both constitutional and nonsporadic type tumor cells. Four of the 8 tumors with WT1 and WIT1 deletions showed loss of constitutional heterozygosity (LOH) for markers limited to the 11p13 region. Seven of 19 Wilms tumors with neither WT1 nor WIT1 deletions also had LOH on 11p; 4 in the 11p15-11p13 region, one in the 11p15 and possibly also 11p13 regions, and two solely in the 11p15 region. Thus, 15 of the 41 Wilms tumors (37%) had WT1 and WIT1 deletions or LOH on 11p, and only 2 of the 27 tumors whose nonneoplastic normal tissues were available for study showed LOH limited to the 11p15 region. None of the 7 non-Wilms childhood renal tumors showed WT1 or WIT1 deletions, or LOH on 11p. These data suggest that Japanese Wilms tumors may be characterized by a higher incidence of the gross WT1 deletion and a lower incidence of LOH limited to the 11p15 region than the Caucasian counterparts. These molecular-genetic features may be contributing to the lower incidence of Wilms tumors in Japanese children than in Caucasian ones.

Fine-needle aspiration of cystic nephroma (multilocular cyst of the kidney)

Cystic nephromas are rare tumors of the kidney most commonly affecting boys or adult females. The fine-needle aspiration cytomorphology has not yet been described. A renal cystic mass in a 56 year old female was aspirated under ultrasound guidance. Papanicolaou stained smears of the cyst fluid revealed markedly atypical cells forming papillary clusters. Subsequent nephrectomy showed a typical cystic nephroma with lining epithelium resembling that seen in the aspirate. The cytomorphology of cystic nephroma has been misdiagnosed as renal cell carcinoma in the literature. Low cellularity, absence of necrosis, and paucity of single cells are features that should raise the possibility of cystic nephroma in a cystic renal mass.

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.

Cystic renal neoplasms of infancy and childhood: a light microscopical, lectin histochemical and immunohistochemical study

Cystic renal neoplasms of infancy and childhood, represented largely by cystic variants of nephroblastoma, form a spectrum of clinicopathological entities with differing behaviours. Cystic nephroma and cystic partially differentiated nephroblastoma occupy the benign end of the tumour spectrum, while polycystic Wilms' tumour forms the malignant end. A wide variety of names, reflecting different theories on aetiology, has been applied to the lesions comprising this spectrum, and this has undoubtedly caused confusion in their recognition and classification. We examined five cases of cystic renal tumours in young children which illustrate the entire spectrum, and lectin histochemical and immunohistochemical analysis of these cases showed a close similarity in the pattern of staining of the three variants of cystic tumours. This finding, which has not previously been reported to our knowledge, supports the concept of a close pathogenetic relationship between these tumours.

Wilms' tumour associated with deep cystic nephroma-like changes: three cases of a putative Wilms' tumour precursor

We describe three cases of Wilms' tumour accompanied by central pericalyceal multicystic lesions closely resembling those seen in cystic nephroma. In continuity with these lesions or elsewhere in the kidney were areas of dysplastic renal tissue of the type sometimes referred to as intralobar nephroblastomatosis. A close homology of tissue differentiation was observed between the dysplastic lesions and the interstitial components of the cystic lesions. These findings support the hypothesis that, in some cases at least, cystic nephroma has more in common with the group of dysplastic lesions referred to as the nephroblastomatosis complex than with the true renal tumours of childhood.

Multilocular cysts of kidney. A study of 29 patients and review of literature

Multilocular renal cyst is a distinct renal tumor whose gross external appearance and absence of normal renal tissue within the septa of loculi distinguish it clearly from other renal cystic lesions. Interlocular septa may contain either (1) fibrous tissue alone or (2) embryonic tissue separating adjacent loculi. Of 29 patients with multilocular renal cysts, 24 underwent a renal-sparing procedure, and only 5 had radical nephrectomy. None of the histologic specimens showed evidence of immature renal tissue or neoplasia. Patients were followed from three months to eight years (mean, 39 months), and no evidence of local recurrence or metastatic disease was found. Because it is difficult to distinguish multilocular renal cyst from cystic Wilms tumor and multicystic clear cell carcinoma on the basis of imaging studies alone, surgical intervention is the only effective method to differentiate multilocular renal cyst from a malignant lesion of the kidney.

Magnetic resonance imaging of cystic, partially differentiated nephroblastoma

The magnetic resonance imaging (MRI) appearance of a cystic, partially differentiated nephroblastoma is described, together with pathologic correlation. The difficulty in reaching a correct preoperative diagnosis even with multimodal imaging techniques is emphasized. MRI is an adjunct to ultrasonography and may be superior to computerized tomography (CT) scan in the evaluation of a child with multiloculated cystic renal mass.

Panlobar nephroblastomatosis: a distinctive form of renal dysplasia associated with Wilms' tumour

An increasing variety of dysplastic lesions of metanephric origin ('the nephroblastomatosis complex') have been recognized as precursors of Wilms' tumour. We describe here four cases of a hitherto unrecognized renal dysplasia associated with Wilms' tumour and having a panlobar distribution. It has many features in common with the intralobar form of nephroblastomatosis, but differs in extending through the full thickness of the renal substance from calyx to capsule. These cases are also characterized by an increased proportion of well-differentiated tissue elements and by the presence, in some cases, of anomalous metanephric differentiation in the pericalyceal tissues or renal capsule. The presence of Wilms' tissue arising deep in the renal substance should alert the pathologist to make a thorough search for associated dysplastic elements in the kidney.

A case of adult mesoblastic nephroma: ultrastructure and discussion of histogenesis

A benign fibromyomatous kidney tumor with deep seated tubular structures in a 20-year-old woman is reported as a case of adult mesoblastic nephroma. Ultrastructural examination confirmed the fibromyomatous nature of the stroma and the tubules appeared to be an integral part of the tumor. The histogenetic relationship to congenital mesoblastic nephroma, Wilms tumor and other tumors is discussed. Radical nephrectomy was performed and the patient remained well 1 year later.

Hyperdiploidy including trisomy 8 in a cystic partially differentiated nephroblastoma

Cystic partially differentiated nephroblastoma (CPDN), a rare, cystic, renal lesion of childhood, has not been previously karyotyped. It is distinguished histologically from multilocular renal cyst by the presence of blastemal cells, and from Wilms' tumor by lack of expansile, solid growth and by indolent clinical behavior. In the present case, ten of 20 analyzed cells from a 3-week culture obtained from the tumor had a clonal, hyperdiploid karyotype. The modal chromosome number was 51, with chromosomes 8, 12, 17, 19, and 20 usually being present in three copies. Trisomy 8 was present in every hyperdiploid cell examined. A normal 46,XY constitutional karyotype was also observed. In degree and significance, the hyperdiploidy of CPDN is thus distinct from that reported in the prognostically unfavorable, anaplastic Wilms' tumor, where the DNA index is typically near-tetraploid. Trisomy 8, as a constitutional mosaicism, has been previously reported in children with bilateral CPDN and/or undifferentiated sarcomas, although none of their tumors were karyotyped. The present findings support a neoplastic nature for CPDN, while emphasizing its pathogenetic distinctiveness from Wilms' tumor, and provide further evidence for significance of trisomy 8 in the pathobiology of this tumor.

Multilocular cyst of the kidney (cystic nephroma) and cystic, partially differentiated nephroblastoma. Terminology and criteria for diagnosis

The entities commonly known as multi-locular cyst of the kidney (MLC) and cystic partially differentiated nephroblastoma (CPDN) were reviewed, based on material in the National Wilms' Tumor Study Pathology Center. The authors recommend several modifications of existing terminology and definitional criteria for these lesions. Because MLC probably represents a neoplastic lesion, the designation "cystic nephroma" (CN) is preferred. This term should be used only for predominantly cystic tumors composed entirely of differentiated tissues, without blastema or other embryonal elements. The designation CPDN should be applied to predominantly cystic lesions, lacking nodular solid regions, in which blastemal or other embryonal cells are present in the septa of the cysts. Solid Wilms' tumor with multifocal cystic change should be distinguished from CPDN. Five cases of CN and 18 cases of CPDN were reviewed. No CN, for which follow-up data was available, showed aggressive behavior. Only one case of CPDN underwent local recurrence, and there were no metastases. In general, nephrectomy alone appears to be adequate therapy for CPDN, but regular monitoring by noninvasive techniques would seem advisable.

Multilocular renal cyst. Scanning and transmission electron microscopic observations

A multilocular renal cyst in a boy aged one year and four months is presented, with particular attention being paid to the nature of the epithelial lining cells. Light and transmission electron microscopy showed the cyst to be lined by a single layer of flattened or cuboidal epithelial cells of relatively uniform morphology. Neither embryonic elements nor nephroblastomatous foci were noted in the intervening stroma. The scanning electron microscopy showed hitherto undescribed surface morphological features of the epithelial lining cells: They were characterized by the presence of one or, occasionally two centrally positioned long cilia and by variably oriented microvilli. The observations presented here suggested that the lining cells of the cyst most closely resembled the principal cells of the collecting ducts, especially those located in the inner medulla of the kidney. An unexpected finding was the additional occurrence of a giant bullous lesion in the right lung of this patient.

Flow cytometric analysis of nephroblastomas and related neoplasms

A total of 59 cases of nephroblastoma and related neoplasms were studied by flow cytometry of paraffin-embedded tissue. According to clinical prognosis, cases were subdivided into three groups: Group 1 (low risk) consisted of congenital mesoblastic nephroma (n = 13) and cystic, partially differentiated nephroblastoma (n = 2). Group 2 (intermediate risk) comprised the various subtypes of "typical" nephroblastoma (n = 24) including cases of fetal rhabdomyomatous nephroblastoma (n = 4). In group 3 (high risk) there were cases of anaplastic nephroblastoma (n = 3), clear cell sarcoma of the kidney or "bone metastasizing renal tumor of childhood" (n = 7), and malignant rhabdoid tumor of the kidney (n = 6). The three clinically different groups of tumors also varied in the proportion of cases with aneuploid tumor DNA stemlines, in S-phase fractions, and in proliferation indices (PI = S + G2 + M). Group 1 was generally characterized by a small number of cases with aneuploid tumor DNA stemlines and low values for S-phase fractions and PI, whereas Group 3 showed the largest number of cases with aneuploid tumor DNA stemlines and high values for S-phase fractions and PI. Group 2 was in between. It is concluded that flow cytometry on paraffin-embedded tissue from pediatric tumors may be a useful adjunct in determining prognosis, and that the subdivision of nephroblastomas and related neoplasms into three prognostically different groups is warranted.

Cystic Nephroma in Children. Report of a Case

A case of cystic nephroma is described in a 20-month-old female. The diagnosis of this rare renal pathologic lesion is essentially based on its pathologic features. The treatment consisted of nephrectomy followed by a brief course of chemotherapy. The literature is reviewed with regard to the pathologic features and treatment of this lesion, which has a favorable prognosis.

Multilocular renal cyst

A case of multilocular renal cyst histologically consistent with clear cell carcinoma is reported. This case is unusual in that the cyst had features indicative of a developmental malformation superimposed by a neoplasm. The controversy over the pathogenesis of multilocular cyst--neoplasm versus developmental anomaly--is unsettled. This case illustrates the possibility that multilocular cysts can be developmental defects which subsequently become the origin of neoplastic transformation of the dysgenetic tissue.

Multicystic nephroblastoma: ultrasound diagnosis (with a pathologic-anatomic commentary)

Multicystic nephroblastoma is a cystic variant of the Wilms' tumor. As such, pathologic identification of blastemal elements in multilocular cystic disease is important in the long term care of patients. A case of this unusual Wilms' tumor is described.

Bilateral cystic nephroblastomas and botryoid sarcoma involving vagina and urinary bladder in a child with microcephaly, arhinencephaly, and bilateral cataracts

The case of a 1-year-old infant with bilateral cystic nephroblastomas, a botryoid sarcoma involving the vagina and urinary bladder, microcephaly, arhinencephaly and bilateral cataracts is reported. The unusual association of these lesions suggests a syndrome due to genetic abnormalities.

Multilocular cyst of kidney with embryonic tissue

A case of a multilocular cyst in a child is documented, and a brief review of reported cases of multilocular cysts in pediatric age groups is presented. These cases can be divided into two subgroups based on the presence or absence of embryonic tissue within the cysts. The significance of this embryonic tissue with regard to histogenesis and prognosis of the multilocular cysts is discussed.

Multilocular renal cyst. Case report, ultrastructure and review of the literature

Multilocular renal cyst is an uncommon focal, unilateral, cystic, epithelial lesion of uncertain pathogenesis. Because nephroblastomatous foci have been found on microscopic examination of several of the reported cases, some authors have proposed that multilocular cysts are differentiated and cystic forms of Wilms' tumour. This proposition is analysed and it is concluded that three possibly interrelated lesions may be defined: (1) Wilms' tumours showing cystic differentiation. (2) Lesions macroscopically indistinguishable from multilocular cyst containing variably differentiated nephroblastomatous foci. All such cases have been described in infants. (3) Typical multilocular renal cysts, which have described in children and adults. Review of the literature shows that several cases have been included in the second category solely because of the presence of small intraseptal tubules. Consequent anomalies of interpretation are highlighted and a further case of multilocular cyst in an adult female is reported in which ultrastructural examination, recorded for the first time, confirms the epithelial nature of the cyst lining cells which resemble simplified renal tubular epithelium.

Adenocarcinoma in multilocular renal cyst

The fifth case of a patient with a multilocular cystic nephroma with an associated adenocarcinoma is reported. The histology of the tumor and biochemical analysis of the cyst fluid are presented and the literature summarized.

Multilocular cyst of the kidney

Five cases of multilocular cyst of the kidney are presented with a follow-up of 8 mo to 13 yr. Two children were treated with partial nephrectomy and three with nephrectomy. Radiation therapy and chemotherapy were not given pre- or postoperatively. Ultrasonography is helpful in preoperative diagnosis of this lesion. A brief review of the literature, differential diagnosis, possible etiology, preoperative evaluation and treatment are discussed.

Benign cystic nephroblastoma

A benign cystic nephroblastoma in a 6-month-old boy is presented. Erroneous interpretation as malignant nephroblastoma led to unnecessarily aggressive therapy. There is no evidence of recurrence or metastatic disease 12 years after the initial resection. As shown in our case and in the others previously reported in the literature, benign cystic nephroblastoma represents a distinct clinicopathological entity which does not show malignant behavior.

Cystic partially differentiated nephroblastoma and multilocular cyst of the kidney. Report of two cases of so-called multilocular cyst of the kidney

Two cases of so-called multilocular cyst of the kidney are presented. Although both cases satisfied all of the criteria which characterize the multilocular cyst of the kidney, one had cystic lesions and neoplastic lesions (nephroblastoma-like lesions) and the other had only cystic lesions and was complicated with hamartoma. We prefer the term "cystic partially differentiated nephroblastoma" as the diagnostic term for the former and "multilocular cyst of the kidney" for the latter. A study of 40 reported cases of multilocular cystic lesions of the kidney revealed that cases having only cystic lesions were distributed in all ages from 4.5 months to 71 years and that cases having neoplastic lesions were seen in infants from 4 months to 2 years.

Case report: cystic partially differentiated nephroblastoma (Wilms tumor)

A case of a cystic partially differentiated nephroblastoma treated with combined chemotherapy after removal in a 2-month old newborn is reported. Cystic partially differentiated nephroblastoma is a newly described clinicopathologic entity, involving elements of a nephroblastoma and cystic disease, and it is believed to be a pathologic derivative of the metanephric blastema and not related to renal dysplasia. Cystic partially differentiated nephroblastoma is distinguished from multilocular cysts of the kidney by the presence of partially differentiated renal elements in the septa of cysts. The aggressive appearance of the cells led to the treatment of this tumor as potentially malignant.