Prenatal diagnosis and postnatal management of congenital mesoblastic nephroma: Experience at a single center in China.

OBJECTIVE: To review the prenatal and postnatal clinical characteristics and pathological subtypes, as well as the surgical outcome for congenital mesoblastic nephroma (CMN) cases. METHOD: A retrospective review was performed in 11 cases with CMN prenatally diagnosed at a single center between 2015 and 2019. The clinical characteristics, surgical outcome, histopathology, and follow-up were retrospectively obtained and reviewed. RESULTS: The median gestational age at which the sonographic diagnosis was made was 35 weeks. Polyhydramnios was found in four (36.4%) cases, and all resulted in a preterm birth. Nine infants had hypertension. Ten cases underwent radical nephrectomy, and one underwent radical nephrectomy and partial adrenalectomy. The pathological results showed that six tumors were classical variants, four mixed variants, and one was a cellular variant. Three cases presented as a stage I, eight as stage II, and no stage III or IV cases were diagnosed. All patients are alive so far. At a median follow-up of 14 months, no local recurrence, or remote metastases were found. CONCLUSION: The prognosis of prenatal CMN cases is excellent after early surgery.

Recurrent and metastatic congenital mesoblastic nephroma: where does the evidence stand?

PURPOSE: Fifty years ago, Bolande described Congenital Mesoblastic Nephroma (CMN) as a benign lesion. Unexpected aggressive clinical behaviors prompted a sub-classification based on histology. Recent molecular genetic evidence has identified the aggressive cellular variant to be the renal manifestation of congenital infantile fibrosarcoma. We submit a reappraisal and analysis of the available literature on recurrent and metastatic CMN. METHODS: An electronic search of PubMed, MEDLINE, EMBASE, and Scopus yielded 38 children with local recurrence and/or metastases. RESULTS: Of the 38 children with local recurrence and/or metastasis, 59% were girls. Median time to recurrence was 6 months (range 1-12 months). The commonest sites of metastases were the lung (39%) and liver (29%). Fifty percent of these children died of disease. The outcome of additional chemotherapy (p = 0.5) did not differ from that of surgery alone. The choice of chemotherapy did not influence the outcome (p = 0.6). CONCLUSIONS: Recurrence and metastasis in cellular CMN are much more common than described earlier and carry a high mortality. Children with cellular and mixed CMN require close clinical and radiological follow-up for a minimum of 12 months after primary surgery. Surgery is the mainstay of the treatment of recurrent and metastatic lesions. Neoadjuvant chemotherapy is recommended only if the lesion is inoperable. Targeted therapy may be an option in treatment of refractory cases.

Renal Tumors in Children Younger Than 12 Months of Age: A 65-Year Single Institution Review.

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

Incidence of benign pathologic findings at partial nephrectomy for solitary renal mass presumed to be renal cell carcinoma on preoperative imaging.

OBJECTIVES: To determine the incidence of benign pathologic findings at partial nephrectomy for a solitary renal lesion when preoperative imaging is reviewed by an experienced team of academic genitourinary radiologists. METHODS: From 1996 to 2004, 143 patients underwent resection of a solitary renal lesion for presumed renal cell carcinoma amenable to partial nephrectomy. Our experienced team of genitourinary radiologists interpreted all preoperative imaging scans. Of the 143 patients, 44 underwent partial nephrectomy for a solitary lesion less than 2 cm, 85 for a lesion 2 to 4 cm, and 14 for a lesion greater than 4 cm. RESULTS: Of the 143 solitary masses resected, 23 revealed benign pathologic findings (16.1%). Ten lesions (43.5%) were angiomyolipomas (AMLs), eight (34.8%) were oncocytomas, three (13.0%) were benign Bosniak-type cysts, and one each was a low-grade spindle cell lesion most consistent with mesoblastic nephroma, and a metanephric adenoma. CONCLUSIONS: A significant fraction of small solitary renal masses presumed to be renal cell carcinoma had benign pathologic findings on resection, despite thorough expert radiologic review. Management should favor parenchyma-sparing approaches, because resection serves not only a therapeutic but also a diagnostic function. Patients should be counseled accordingly when faced with the diagnosis of renal mass.

Tumores renales en niños menores de un año / Renal tumors in infants aged less than 1 year

Objetivo: Conocer la frecuencia y distribución de los tumores renales diagnosticados en una unidad de oncología pediátrica en niños menores de un año, sus características clínicas, anatomopatológicas, tratamientos utilizados y evolución. Material y métodos: Estudio retrospectivo de tumores renales primarios diagnosticados en lactantes en un hospital pediátrico, desde 1972 hasta febrero de 2003. Resultados: Obtuvimos 25 niños menores de un año (18,2 %), de un total de 137 tumores renales registrados. Diecisiete niños y 8 niñas. El más frecuente fue el nefroblastoma (15/25), seguido del nefroma mesoblástico (9/25), y uno fue un tumor rabdoide. La media de edad al diagnóstico fue de 4,8 meses (rango, 1 día-11 meses), la mediana de 5,03 meses; para los nefromas mesoblásticos la mediana fue de 1 día (rango, 1 día-3 meses). La forma de presentación fue como masa abdominal en 20 de ellos, en cuatro hematuria y un recién nacido empezó con obstrucción intestinal (nefroma mesoblástico). Presentaron hipertensión arterial 12/25 niños; 9/15 casos de nefroblastomas eran estadio I; uno, estadio II; uno, estadio III; dos, estadio IV; uno, estadio V, y uno falleció antes de la cirugía. La supervivencia global de los nefroblastomas a los 5 años es de 0,67 (error estándar [EE]: 0,12); y del nefroma mesoblástico de 0,89 (EE: 0,1), con un tiempo de supervivencia media de 290 meses. Conclusiones: En los niños menores de 6 meses el nefroma mesoblástico es más frecuente que el tumor de Wilms, siendo el tratamiento inicial de elección la cirugía, ya que este tipo de tumor es poco quimiosensible y la quimioterapia es peor tolerada en los lactantes

Objective: To determine the frequency and distribution of primary renal tumors diagnosed in a pediatric oncology unit in children younger than 1 year and identify their clinical and histopathological characteristics, the treatment used, and outcomes. Material and methods: We retrospectively reviewed the medical records of infants with primary tumors of the kidney diagnosed between January 1972 and February 2003. Results: A total of 137 tumors were diagnosed in our unit during the period studied. Of these, 25 (18.2 %) occurred in infants aged less than 1 year. There were 17 boys and 8 girls. The most prevalent tumor in this age group was Wilms' tumor (WT) in 15 patients, followed by mesoblastic nephroma (MN) in 9 patients and rhabdoid tumor in 1 patient. The mean age at diagnosis of WT was 4.8 months (range: 1 day-11 months), with a median of 5.03 months. The median age at diagnosis of MN was 1 day (range: 1 day-3 months). Presenting symptoms consisted of abdominal mass in 20 patients, hematuria in 4 patients and intestinal pseudo-occlusion (MN) in 1 patient. High blood pressure was found in 12 of the 25 patients. Among the 15 WT, 9 were stage I, 1 was stage II, one was stage III, 2 were stage IV, and 1 was stage V. One patient died before surgery. Overall survival at 5 years was 0.67 (SE 0.12) for WT and 0.89 (SE 0.1) for MN, respectively, with a mean follow-up of 290 months. Conclusions: MN was more frequent than WT in infants aged less than 6 months. The first-line therapy in these patients is surgery since this type of tumor shows little chemosensitivity and chemotherapy is poorly tolerated in infants

Renal tumors in infants less than 6 months of age.

BACKGROUND/PURPOSE: Renal tumors are rare in infants less than 6 months of age and may have associated paraneoplastic symptoms. To better define the characteristics of these tumors the authors reviewed their 10-year institutional experience. METHODS: The authors searched the pathology database to identify all renal tumors resected at their institution since 1992 (after IRB approval and guidelines). The clinical presentation, operative details, pathology, and outcome for all children < or = 6 months of age were reviewed. RESULTS: Of 101 children who had renal tumors resected during this period, 11 (11 %) were 6 months of age or less. Histopathologic examination showed congenital mesoblastic nephroma (CMN) in 7 patients (4 with cellular features), Wilms' tumor in 3 patients, and ossifying renal tumor of infancy in 1. Renal masses were detected antenatally in 2 patients and during newborn examination in 1 patient; however, the mean age at diagnosis was 72 +/- 18 days. Ten children had a palpable abdominal mass, 3 had gross hematuria, and 6 had hypertension (4 CMN; 2 Wilms'). Only 1 child had hypercalcemia (cellular CMN). Ten infants had nephroureterectomy, and 1 had a partial nephrectomy. All patients had either stage I or II disease. At follow-up (mean 4.2 +/- 1.2 years) 10 patients are alive with no evidence of disease. One newborn with hydrops and a very large congenital Wilms' tumor had abdominal compartment syndrome and died during surgery. CONCLUSIONS: About 10% of renal masses may occur in infants less than 6 months of age. Although mesoblastic nephroma is the most common renal tumor in this age group, Wilms' tumor also may be seen. Paraneoplastic syndromes, such as hypertension and hypercalcemia, are common in these infants and are not specific for tumor type. These tumors generally present at an early stage and have an excellent prognosis overall.