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.     

Renal cystic diseases: a review

This review aims to assist in the categorization of inherited, developmental, and acquired cystic disease of the kidney as well as to provide a pertinent, up-to-date bibliography. The conditions included are autosomal-dominant polycystic kidney disease, autosomal-recessive polycystic kidney disease, unilateral renal cystic disease (localized cystic disease), renal simple cysts, multicystic dysplastic kidney, pluricystic kidney of the multiple malformation syndromes, juvenile nephronophthisis and medullary cystic disease, medullary sponge kidney, primary glomerulocystic kidney disease, and glomerulocystic kidney associated with several systemic disorders mainly of genetic or chromosomal etiology, cystic kidney in tuberous sclerosis, and in von Hippel-Lindau syndrome, cystic nephroma, cystic variant of congenital mesoblastic nephroma, mixed epithelial stromal tumor of the kidney, renal lymphangioma, pyelocalyceal cyst, peripylic cyst and perinephric pseudocyst, acquired renal cystic disease of long-term dialysis, and cystic renal cell carcinoma and sarcoma. Whereas the gross and histologic appearance of some of these conditions may be diagnostic, clinical and sometimes molecular studies may be necessary to define other types.     

Benign multilocular cystic nephroma versus cystic nephroblastoma. A review and classification of cystic metanephric neoplasms (author's transl)]

A review of reported cases of cystic metanephric tumors is given. It is shown that among these neoplasms two distinct pathologic entities exist: the cystic nephroblastoma and the benign multilocular cystic nephroma. The former, a benign variant of Wilms' tumor, is found in children of younger age. Its possible precursor is the infantile form of nephroblastomatosis. The second neoplasm, a clinically and biologically benign tumor, occurs in older children and in half of the cases it is also encountered in adults. It derives from metanephric hamartomas which have their origin in the huvenile form of nephroblastomatosis.     

Clinico-pathological profile of 22 cases of cystic renal dysplasia

Renal dysplasia is one of the major renal developmental anomaly characterized by abnormal structural organization and development of metanephric elements. It is usually detected antenatally or in early childhood. The kidney may be multicystic, aplastic, hypoplastic or duplex. We studied 22 cases of cystic renal dysplasia diagnosed over a period often years to identify the spectrum of morphological changes in dysplastic kidney, with special emphasis on mesenchymal changes. Clinical, radiological and gross morphologicalfeatures were noted. Microscopic features were studied in detail, including the epithelial and mesenchymal changes. Twenty-one of the 22 cases studied were children. One case was a 21-year-old adult, which is a rare age at presentation. Male to female ratio was 1.1:1. One of our patients had contra-lateral ureteric stenosis, a rare anomaly reported with renal dysplasia. Ten patients, all autopsy cases, had multi-system congenital anomalies. As cystic renal dysplasia is not a hereditary disease, it must be differentiated from polycystic kidney disease. Other differential diagnoses are cystic nephroma and cystic partially differentiated nephroblastoma. Histopathological examination is the final diagnostic tool since radiological features alone may not be sufficient to exclude other cystic renal lesions. Cartilage may not be seen in all cases of renal dysplasia. Once diagnosed, other associated anomalies should also be looked for.     

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.     

Multicystic congenital mesoblastic nephroma

This report describes an unusual example of congenital mesoblastic nephroma cellular variant that presented in a 1-week-old neonate as a multicystic tumor of the kidney. Extensive pseudocystic cavitation resulted from progressive accumulation of ground substance in a loosely myxoid tissue composed of stellate- and spindle-shaped cells that compressed and infiltrated renal tissue. The cells of the tumor were positive for vimentin and smooth muscle actin. The patient is alive and well 16 years after surgery. Differential diagnosis from segmental cystic dysplasia, cystic intralobar nephrogenic rest, cystic nephroma, cystic partially differentiated nephroblastoma, cystic nephroblastoma, and cystic clear cell sarcoma of the kidney, all of which may present at this age, is discussed.     

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.     

Benign tumors and tumor-like lesions of the adult kidney. Part II: Benign mesenchymal and mixed neoplasms, and tumor-like lesions

In this review article the benign tumors and tumor-like lesions of the adult kidney are discussed. The incidence of benign renal tumors is low, especially when compared to renal cell carcinomas, as most are detected incidentally or at autopsy. Some of these tumors, as their names imply, are unique to the kidney, e.g., renal adenoma, metanephric adenoma, renal oncocytoma, nephrogenic adenofibroma, mesoblastic nephroma, capsuloma, juxtaglomerular cell tumor, renomedullary interstitial cell tumor (medullary fibroma), cystic nephroma, cystic partially differentiated nephroblastoma, and cystic hamartoma of the renal pelvis, while others, such as angiomyolipoma, leiomyoma, hemangioma, lipoma, etc., are not unique to the kidney and show similar morphologic features in the other sites they affect. Of the tumor-like lesions, xanthogranulomatous pyelonephritis, malakoplakia, and renal cysts are the most common. The other entities, such as fibroepithelial polyp, are rare, most having been the topic of case reports. In Part I of this paper the benign epithelial tumors of the kidney were previously discussed. This paper (Part II) is devoted to the benign mesenchymal tumors, mixed mesenchymal and epithelial tumors, and the tumor-like lesions.     

Histopathological study of congenital cystic kidneys with special reference to the multicystic, dysplastic type

Ten autopsy cases of congenital cystic kidneys were studied by histopathological examination. Eight cases with dysplastic type revealed immature mesoderm, cartilage, localized tight fibrous tissue, hemangiomatous lesion consisting of arterio-capillary-venous elements, extramedullary hematopoiesis, primitive lymph nodes, adipose tissue, and abundant neural tissue in the kidney as well as cystic lesions. These findings strongly suggest that congenital cystic kidneys of dysplastic type are derived from hamartoma or hamartomatous changes chiefly consisting of mesodermal tissue, most of which corresponds to tissue anomaly and is very close to the aberrant form of Wilms' tumor. The presence of focal fibrosis and lymphoid cell infiltration forming focal renal tissue destruction suggest local disturbance of tissue differentiation due to some casual elements. As common feature of this type, it is revealed that the babies show lower weight for their fetal ages and die shortly after birth or are delivered as still birth due to hypoplasia and atelectasis of the pulmonary tissue.     

HISTOPATHOLOGICAL STUDY OF CONGENITAL CYSTIC KIDNEYS WITH SPECIAL REFERENCE TO THE MULTICYSTIC, DYSPLASTIC TYPE

Ten autopsy cases of congenital cystic kidneys were studied by histopathological examination. Eight cases with dysplastic type revealed immature mesoderm, cartilage, localized tight fibrous tissue, hemangiomatous lesion consisting of arterlo-capillary-venous elements, extramedullary hematopoiesis, primitive lymph nodes, adipose tissue, and abundant neural tissue in the kidney as well as cystic lesions. These findings strongly suggest that congenital cystic kidneys of dysplastic type are derived from hamartoma or hamartomatous changes chiefly consisting of mesodermal tissue, most of which corresponds to tissue anomaly and is very close to the aberrant form of Wilms'tumor. The presence of focal fibrosis and lymphoid cell infiltration forming focal renal tissue destruction suggest local disturbance of tissue dmerentiation due to some causal elements. As common feature of this type, it is revealed that the babies show lower weights for their fetal ages and die shortly after birth or are delivered as still birth due to hypoplasia and atelectasis of the pulmonary tissue.     

Uretheral invagination of multilocular cystic nephroma; a case report of a new pathologic variant

Background: The multilocular cystic nephroma (MLCN) is a unilateral cystic neoplasm of the kidney exhibiting benign biological behavior. The etiology and histopathogenesis of the disease is controversial (dysplastic/hamartomous/neoplastic). MLCNs show bimodal age distribution, with peak incidence occurring at 2-4 years of age and between the fourth and sixth decades. The male to female ratio in patients aged below 4 years is 3:1, which reverses to 1:8 between the fourth and sixth decades. Patients and methods: A 59-year-old female patient presented with left flank pain and abdominal pain. Ultrasound (US) revealed 220×109×82 mm multiple septated hyperechoic kidney cysts with a semi-solid appearance. MRI showed a 245×119×98 mm multilocular cystic renal mass in the left kidney with hypointense appearance in T1-weighted images and hyperintense in T2-weighted images, and multicystic appearance in ureter projection, the largest portion measuring 17 mm in diameter. Radical nephrectomy was planned with the pre-diagnosis of multilocular cystic nephroma or multicystic renal cell carcinoma. Results: The patient underwent transperitoneal radical nephroureterectomy. The immunohistopathological examination revealed MLCN with ureteral invagination. Conclusion: The etiology, pathogenesis, and genetic basis of multilocular cystic nephroma are currently unknown. This tumor is confused with cystic partially differentiated nephroblastoma and cystic Wilms tumor in childhood, and multilocular cystic renal cell carcinoma, clear cell papillary renal cell carcinoma, and tubulocystic carcinoma in adults. The association of this tumor with pleuropulmonary blastoma in children exhibits genetic inheritance. US control is particularly recommended in siblings of these children. Albeit rare, the disease can occur as a bilateral synchronous or metachronous lesion. There are four reports of cases with recurrence in the literature. The laparoscopic partial nephrectomy is the recommended treatment method in patients with sufficient renal reserve that are found to be free of malignancy in the frozen section examination. The symptoms of hematuria and flank pain can be associated with invagination of the cysts into the pelvis and intrarenal rupture of the cysts. The invagination of cysts into the pelvis has been previously described. The authors consider that this was the first case of MLCN in the literature exhibiting invagination into the ureter.     

Blastemal cells of nephroblastomatosis complex share an onco-developmental antigen with embryonic kidney and Wilms'' tumor. An immunohistochemical study on polysialic acid distribution.

Previous investigations on polysialic acid of the neural cell adhesion molecule NCAM in human kidney have demonstrated its presence during nephrogenesis in embryonic kidney, absence in normal adult kidney, and reexpression in Wilms' tumor. These data showed that polysialic acid of NCAM is an onco-developmental antigen in human kidney and provided more direct evidence for the metanephric origin of Wilms' tumor. In the present study, five cases of Wilms' tumor associated with nephroblastomatosis complexes were immunohistochemically investigated with a monoclonal antibody for the presence of polysialic acid. Regardless of the type of nephroblastomatosis complex, ie, renal nodular blastema, simple tubular metanephric hamartoma, sclerosing metanephric hamartoma with adenoma, or incipient Wilms' tumor, immunoreactivity for polysialic acid was found in the blastemal cells, but was undetectable in all other structural elements. Because only blastemal cells exhibited a characteristic feature of embryonal differentiating metanephric derivatives, it appears that Wilms' tumor has its origin not exclusively in nodular renal blastema but rather in blastemal cells present in the various forms of nephroblastomatosis complex. The presence of polysialic acid of NCAM in blastemal cells in such lesions indicates that further events in addition to the expression of the embryonic form of this cell adhesion molecule may be involved in the pathogenesis of Wilms' tumor.     

Wilms'' tumour and renal dysplasia: an hypothesis

The incidence of renal dysplasia in a series of Wilms' tumours is presented. The distribution of such lesions is discussed, together with their course of development and regression. The kidney is regarded as a particularly suitable organ for studying the relation between dysplasia and neoplasia. A schema is suggested for this association with regard to Wilms' tumour.     

Embryonal nephroma in an adult fowl

Nephroblastoma or embryonal nephroma is a renal tumor that is rarely seen in chickens older than 5 weeks. Avian leukosis viruses may cause nephroblastoma in the fowl. The carcass of a 2-year-old native fowl was referred for post-mortem examination. There was a large and cystic mass in the abdominal cavity. Based on the histopathological findings, the mass was diagnosed as nephroblastoma.     

Neuroglial tissue in partially cystic Wilms'' tumour

Wilms' tumour (nephroblastoma), the commonest malignant renal tumour of childhood, is thought to be derived from metanephric blastema and a majority of cases show the classical triphasic pattern of blastema, stroma and epithelium. There is usually little difficulty in making a correct histological diagnosis, but problems can arise due to the extraordinary potential of metanephric blastema to differentiate into a wide variety of heterologous tissues. Here we report, probably for the first time, two cases of Wilms' tumour which contained prominent quantities of neuroglial tissue. The classification of these cases as Wilms' tumours rather than renal teratomas is discussed.     

Bilateral mixed epithelial stromal tumor in an end-stage renal disease patient: the first case report

Although first intimated in the 1970s, mixed epithelial stromal tumor has been recognized as a diagnostic entity for less than 10 years, with an identity that has been challenged by overlap between other cystic renal neoplasms, most notably with cystic nephroma. We report the first case of a bilateral mixed epithelial stromal tumor occurring in a 41-year-old dialysis-dependent woman, notably also the first case reported in a patient with end-stage renal disease. The neoplasms occurred 5 years apart and were diagnosed as mixed epithelial stromal tumor in both instances. We describe the presentation and pertinent radiologic, histologic, and immunophenotypic findings of these neoplasms with a review of the current debate regarding mixed epithelial stromal tumor and cystic nephroma taxonomy.     

Spectrum of cystic variants of Wilm's tumour: cystic nephroma (multilocular cyst) and cystic partially differentiated nephroma--a report of four cases.

Two cases of cystic nephroma (multilocular cyst of the kidney), and one case each of cystic partially differentiated nephroblastoma (CPDN) and rhabdomyomatous Wilms' tumour are described. All were male and in the pediatric age group. Grossly tumours were unilateral, unicentric and multiloculated. The need for proper designation of these lesions is highlighted because of difference in the treatment and prognosis of these tumours.     

Cystic hamartoma of the renal pelvis: a rare pathologic entity.

We report a case of a rare cystic renal tumor previously termed cystic hamartoma of the renal pelvis. A 53-year-old woman presented to her gynecologist with menometorrhagia. She subsequently had a computed tomographic scan that demonstrated an incidental cystic mass in the lower pole of the left kidney. Histologically, the tumor was composed of a mixture of benign mesenchymal and epithelial components. The stroma consisted of spindle cells with monomorphic nuclei and abundant eosinophilic cytoplasm that resembled smooth muscle and that reacted positively with antibodies to alpha-smooth muscle actin, desmin, and vimentin. The epithelial component was composed mostly of cysts lined by cuboidal-to-columnar epithelium. Focal dilated cysts were lined by epithelium with oncocytic features. We think that this entity is distinct from other renal tumors, including mesoblastic nephroma, cystic nephroma, or a cystic, partially differentiated nephroblastoma, and that it is best classified as a cystic hamartoma of the renal pelvis.     

A new precursor lesion of Wilms' tumour (nephroblastoma): intralobar multifocal nephroblastomatosis

Almost half of the kidneys containing Wilms' tumours also contain persistent renal blastema in one or more of its forms. Persistent renal blastema is present in almost all cases of bilateral nephroblastoma. Multifocal superficial nephroblastemomatosis is the best known form of persistent renal blastema, and there is good evidence that it is a precursor of nephroblastoma. This paper reports four cases of a second, deep cortical type of nephroblastomatosis. This type of persistent renal blastema appears to be a precursor of a distinct histologic subtype of nephroblastoma, and differs from multifocal superficial nephroblastomatosis also in its teratological background.