General Information About Congenital Mesoblastic Nephroma
Mesoblastic nephroma comprises about 5% of childhood kidney tumors, and more than 90% of cases appear within the first year of life. It is the most common kidney tumor found in infants younger than 3 months. The median age of diagnosis is 1 to 2 months. Twice as many males as females are diagnosed. The diagnosis should be questioned when applied to individuals older than 2 years.
The histiocytic diseases in children and adults include three major classes of disorders. Only Langerhans cell histiocytosis (LCH), a dendritic cell disorder, is discussed in detail in this summary. Erdheim-Chester disease (primarily found in adults) and juvenile xanthogranuloma (diagnosed in children and adults) are macrophage disorders. Other disorders of the macrophage/monocytoid lineages include Rosai-Dorfman disease and hemophagocytic lymphohistiocytosis. Malignant disorders include malignant...
When patients are diagnosed in the first 7 months of life, the 5-year event-free survival (EFS) rate is 94%, and the overall survival (OS) rate is 96%. In a report from the United Kingdom of 50 children with mesoblastic nephroma studied on clinical trials and 80 cases from the national registry in the same time period, there were no deaths.
Grossly, mesoblastic nephromas appear as solitary, unilateral masses indistinguishable from nephroblastoma. Microscopically, they consist of spindled mesenchymal cells. Mesoblastic nephroma can be divided into the following two major types:
Classic. Classic mesoblastic nephroma is often diagnosed by prenatal ultrasound or within 3 months after birth and closely resembles infantile fibromatosis.
Cellular. A potential linkage between infantile fibrosarcoma and cellular mesoblastic nephroma is suggested because both contain the same t(12;15)(p13;q25) translocation, which results in the ETV6/NTRK3 fusion.
The risk for recurrence in mesoblastic nephroma is closely associated with the presence of a cellular component and with stage.
(Refer to the Wilms tumor Clinical Features and Diagnostic and Staging Evaluation sections of this summary for more information about the clinical features and diagnostic evaluation of childhood kidney tumors.)
Standard Treatment Options for Congenital Mesoblastic Nephroma
Standard treatment options for congenital mesoblastic nephroma include the following:
A prospective clinical trial enrolled 50 patients with congenital mesoblastic nephroma.
The results confirmed that complete surgical resection, which includes the entire capsule, is adequate therapy for most patients with mesoblastic nephroma.
Only 2 of 50 patients died.
Patients were at increased risk of local and eventually metastatic recurrence if there was stage III disease (incomplete resection and/or histologically positive resection margin), cellular subtype, and age 3 months or older at diagnosis. Because of the small numbers of patients and the overlapping incidence of these characteristics (5 of 50 patients), the significance of the individual characteristics could not be discerned.