Pediatric renal tumors represent a diverse group, which include Wilms' tumor (WT), renal cell carcinoma (RCC), clear cell sarcoma of the kidney (CCSK), congenital mesoblastic nephroma, malignant rhabdoid tumor of the kidney (MRTK) and primitive neuroectodermal tumor. WT (85%) and RCC (8%) are the most prevalent types. WT predominates among the 1- to 10-year age group, but RCC exceeds WT in children over age 10 years. Pediatric renal tumors are genetically, histologically and clinically heterogeneous. The overall survival for children with localized WT is currently more than 90%, whereas poorer survival rates are observed for anaplastic WT, metastatic WT, metastatic CCSK, MRTK, metastatic RCC and relapsed WT. Therefore risk-stratified treatment is important to minimize treatment morbidity while preserving survival. This review focuses on distinct characteristics of each tumor type and optimal stratified treatment.
Carcinoma, Renal Cell ; Child ; Humans ; Kidney ; Nephroma, Mesoblastic ; Neuroectodermal Tumors, Primitive ; Rhabdoid Tumor ; Sarcoma, Clear Cell ; Survival Rate ; Wilms Tumor

Congenital mesoblastic nephroma is a rare renal tumor that is diagnosed during pregnancy and is associated with polyhydramnios, prematurity, and neonatal hypertension. Differential diagnoses include Wilms tumor, adrenal neuroblastoma, and other abdominal tumors. We report a case of congenital mesoblastic nephroma detected by prenatal ultrasonography as a large fetal renal mass with polyhydramnios at 32 weeks of gestation. Ultrasonography showed a 6x6-cm complex, solid, hyperechoic, round mass in the right kidney. At 35 weeks of gestation, the patient was admitted with preterm premature rupture of membranes and the baby was delivered vaginally. Postnatal ultrasonography and computed tomography showed a heterogeneous solid mass on the right kidney. At the end of the first week of life, a right nephrectomy was performed and subsequent pathological examination confirmed a cellular variant of congenital mesoblastic nephroma with a high mitotic count. Postoperative adjuvant chemotherapy was administered. The newborn was discharged in good condition.
Chemotherapy, Adjuvant ; Diagnosis, Differential ; Drug Therapy ; Humans ; Hypertension ; Infant, Newborn ; Kidney ; Membranes ; Nephrectomy ; Nephroma, Mesoblastic* ; Neuroblastoma ; Polyhydramnios ; Pregnancy ; Prenatal Diagnosis* ; Rupture ; Ultrasonography ; Ultrasonography, Prenatal ; Wilms Tumor

Congenital mesoblastic nephroma (CMN) is the most common renal tumor in the first year of life. Here, we present unique findings of cellular variant CMN seen on prenatal and postnatal MRI with diffusion-weighted imaging (DWI).The mass was well-visualized on prenatal MR DWI with diffusion restriction in the solid portions. After excision of the mass, follow-up whole body MRI with DWI helped identify local tumor recurrence with suspicious liver metastasis. This hepatic lesion also showed diffusion restriction.
Adult ; Combined Modality Therapy ; Diffusion Magnetic Resonance Imaging/*methods ; Female ; Humans ; Infant, Newborn ; Kidney Neoplasms/*congenital/therapy ; Liver Neoplasms/*secondary/therapy ; Nephroma, Mesoblastic/*congenital/therapy ; Pregnancy

Adenofibroma ; metabolism ; pathology ; Antigens, CD34 ; metabolism ; Child, Preschool ; Diagnosis, Differential ; Female ; Humans ; Kidney Neoplasms ; metabolism ; pathology ; surgery ; Neoplasms, Germ Cell and Embryonal ; metabolism ; pathology ; surgery ; Nephroma, Mesoblastic ; metabolism ; pathology ; Sarcoma, Clear Cell ; metabolism ; pathology ; Stromal Cells ; metabolism ; pathology ; Vimentin ; metabolism

OBJECTIVETo study the clinicopathologic features, immunophenotype and differential diagnosis of mixed epithelial and stromal tumor of kidney (MEST) and adult cystic nephroma (CN).

METHODSFive cases of MEST and 4 cases of CN were retrospectively analyzed. Immunohistochemical study was carried out and the literature was reviewed.

RESULTSAll of the five patients with MEST were females. Their median age was 45 years. For CN, there were 3 males and 1 female and their median age was 41 years. All patients presented with loin pain and hematuria. On gross examination, MEST was well-circumscribed but non-encapsulated. There was no evidence of haemorrhage or necrosis. Three of the cases were solid in nature. One was composed of a mixture of solid and cystic elements, while the remaining case showed a multicystic cut surface bridged by thick fibrous septa. On the other hand, CN were well-circumscribed and encapsulated. They were multiloculated cystic in nature. The cystic spaces were separated by thin septa and there was no significant solid or necrotic component. Histologically, MEST consisted of proliferation of cystically dilated glands admixed with spindly stromal cells with various cellularity and growth patterns. Both the glandular and stromal elements were well-differentiated with no cytologic atypia identified. The glandular structures in 2 of the cases were partially lined by endometrial or tubal epithelium. In contrast, the thin-walled cystic spaces in CN were lined by a single layer of epithelium.Immunohistochemical study showed that the epithelial cells were positive for pan-cytokeratin and epithelial membrane antigen. The spindle cells in MEST expressed vimentin (5/5), smooth muscle actin (3/5), desmin (4/5), CD10 (5/5), estrogen receptor (4/5) and progesterone receptor (4/5). They were negative for HMB45, CD34, CD117 and S-100 protein. On the other hand, the spindle cells in CN were variably positive for vimentin (4/4), smooth muscle actin (4/4), desmin (1/4), estrogen receptor (3/4) and progesterone receptor (1/4). They were negative for CD10, HMB45, CD34, CD117 and S-100 protein.

CONCLUSIONSBoth MEST and CN are uncommon renal neoplasm. Most of them run a benign clinical course. The stromal cells in MEST show smooth muscle or myofibroblastic differentiation. Areas demonstrating Müllerian features also existed in some cases. MEST and CN share overlapping histological and immunohistochemical features, and may represent spectrum of the same group of lesions.

Actins ; metabolism ; Adult ; Carcinoma, Renal Cell ; pathology ; Desmin ; metabolism ; Diagnosis, Differential ; Epithelial Cells ; metabolism ; pathology ; Female ; Follow-Up Studies ; Humans ; Kidney Neoplasms ; metabolism ; pathology ; Male ; Middle Aged ; Neoplasms, Complex and Mixed ; metabolism ; pathology ; Neoplasms, Cystic, Mucinous, and Serous ; metabolism ; pathology ; Nephroma, Mesoblastic ; pathology ; Receptors, Estrogen ; metabolism ; Retrospective Studies ; Stromal Cells ; metabolism ; pathology ; Vimentin ; metabolism

Diagnosis, Differential ; Humans ; Kidney ; pathology ; Kidney Neoplasms ; diagnosis ; pathology ; Nephroma, Mesoblastic ; diagnosis ; pathology

Although congenital renal tumors are rare, congenital mesoblastic nephroma (CMN) is the most common renal tumor in early infancy. It is non-metastatic, well differentiated, amenable to surgical removal, and carries a good prognosis. Polyhydramnios has been detected in most of the published cases of CMN. However, we experienced a rare case of fetal CMN associated with oligohydramnios. A 28-yr old woman at 34 weeks of gestation was referred to our hospital for oligohydramnios and a fetal abdominal mass. An ultrasonography revealed a huge, well-encapsulated mass arising from the right kidney. An emergency cesarean section was performed due to fetal distress. After birth, despite intensive neonatal care, the baby died because of renal failure, disseminated intravascular coagulopathy, pulmonary edema, together with other problems.
Pregnancy ; Oligohydramnios/*diagnosis/therapy ; Nephroma, Mesoblastic/*diagnosis/therapy ; Kidney Neoplasms/*diagnosis/therapy ; Infant, Newborn ; Humans ; Fetal Diseases/etiology/prevention & control ; Female ; Fatal Outcome ; Cesarean Section ; Adult

The descriptive term "mixed epithelial and stromal tumor of the kidney" was recently proposed for a group of renal tumors characterized histologically by a mixture of stromal and epithelial proliferation. It is a rare benign neoplasm of the kidney which has been reported under various names such as adult type mesoblastic nephroma or others. We report a case of mixed epithelial and stromal tumor in a 47 yr old female patient presenting as a partly cystic and partly solid renal mass. Microscopically, the tumor exhibited spindle cell component in solid portion and epithelial proliferation around microcystic areas. Immunoreactive profiles and ultrastructural examination suggested myofibroblastic nature of the stromal cells. We believe this case exemplifies a unique adult renal tumor displaying both epithelial and stromal neoplastic component and has a few unusual features worthy of attention.
Nephroma, Mesoblastic/pathology ; Neoplasms, Glandular and Epithelial/*pathology ; Middle Aged ; Kidney Neoplasms/*pathology ; Humans ; Female ; Diagnosis, Differential

A multilocular cyst of kidney is a rare pathological entity, which has been reported in the literature under several names. These various names reflect the controversy surrounding their nature. This tumor is traditionally regarded as benign in nature and a nephrectomy has to be performed because of the difficulty in its accurate diagnosis. Malignant recurrence of a multilocular cyst of kidney has an even rarer incidence, with only a few cases having been reported. We report a case of 50-year-old male, with an incidentally detected right renal cystic mass. This mass was pathologically confirmed as a multilocular cyst of kidney after a radical nephrectomy, which locally recurred as a malignant mesoblastic nephroma.
Diagnosis ; Humans ; Incidence ; Kidney Diseases, Cystic ; Kidney* ; Male ; Middle Aged ; Nephrectomy ; Nephroma, Mesoblastic ; Recurrence*

OBJECTIVE: Ultrasonography is screening modality of choice and plays an important role in prenatal diagnosis of various diseases and neoplasm of fetus. Recently, Magnetic Resonance Imaging was used as a diagnosis tool to fetal disease. We would like to evaluate efficacy of ultrasonography and magnetic resonance imaging for the diagnosis of fetal abdominal solid tumor. METHODS: Among 2,055 cases of abnormal ultrasonography findings detected by prenatal ultrasonography from January 1996 and June 2002, a comparison between the diagnosis made by prenatal ultrasonography, fetal magnetic resonance imaging (MRI), postnatal radiological studies and histopathologic studies was made in four cases with fetal abdominal solid tumor. RESULTS: The first case was diagnosed as adrenal tumor or hepatic tumor by US, hemangioedothelioma of liver by fetal MRI, and confirmed as hemangioendothelioma postnatally. The second case showed concordance with mesoblastic nephroma among the diagnosis made by US, fetal MRI, and postnatal histopathologic studies. The third case was diagnosed as extrathoracic pulmonary sequestration by US and MRI, and the same diagnosis was made by postnatal histopathologic studies. The fourth case was suspected as kidney tumor by US and was diagnosed as adrenal as adrenal neuroblastoma postoperatively. CONCLUSION: Fetal solid tumor is not a common disorder, but the location, size and orgin of tumor plays important role in the prognosis of neonatal period; additional workup by fetal MRI would improve the diagnosis of such tumors.
Bronchopulmonary Sequestration ; Diagnosis* ; Fetal Diseases ; Fetus ; Hemangioendothelioma ; Kidney ; Liver ; Magnetic Resonance Imaging ; Mass Screening ; Nephroma, Mesoblastic ; Neuroblastoma ; Prenatal Diagnosis ; Prognosis ; Ultrasonography ; Ultrasonography, Prenatal