Besides its histological appearance, various features of this disease aid in making a differential diagnosis that distinguish it from the following childhood neoplasms:

Wilms tumor is the most common childhood kidney neoplasm, representing some 85% of cases. Unlike mesoblastic nephroma, <2% of Wilms tumor patients present at under 3 months of age and most present in patients of >3 years of age. Bilateral kidney tumors, concurrent birth defects, and/or metastatic disease at presentation favor a diagnosis of Wilms tumor. congenital infantile sarcoma is a rare aggressive sarcoma typically presenting in the lower extremities, head, or neck of infants during their first year of life. The histology, association with the ETV6-NRTK3 fusion gene along with certain chromosome trisomies, and the distribution of markers for cell type (i.e. cyclin D1 and Beta-catenin) within this tumor are the same as those found in cellular mesoblastic nephroma. Mesoblastic nephroma and congenital infantile sarcoma appear to be the same diseases with mesoblastic lymphoma originating in the kidney and congenital infantile sarcoma originating in non-renal tissues. Rhabdoid tumor, which accounts for 5-10% of childhood kidney neoplasms, occurs predominantly in children from 1 to 2 years of age. Unlike mesoblastic nephroma, rhabdoid tumors may present with tumors in other tissues including in ~13% of cases, the brain. Rhabdoid tumors have a distinctive histology and abnormalities (i.e. loss of heterozygosity, single nucleotide polymorphism, and deletions) in chromosome 22. Clear cell sarcoma of the kidney, which is responsible for 5-10% of childhood pediatric tumors, occurs predominantly in children from 2 to 3 years of age.
Signs and symptoms
In both the American Psychiatric Associations DSM-5 and the World Health Organizations ICD-10, the same criteria used to diagnose bipolar disorder in adults are used to make the diagnosis in children with some adjustments to account for differences in age and developmental stage. For example, the DSM-5 specifies that in children, depressive episodes can manifest as persistently irritable moods.In diagnosing manic episodes, it is important to compare the changes in mood and behavior to the childs normal mood and behaviors at baseline instead of to other children or adults. For example, grandiosity (i.e., unrealistic overestimation of ones intelligence, talent, or abilities) is normal at varying degrees during childhood and adolescence. Therefore, grandiosity is only considered symptomatic of mania in children when the beliefs are held despite being presented with concrete evidence otherwise or when they lead to a child attempting activities that are clearly dangerous, and most importantly, when the grandiose beliefs are an obvious change from that particular childs normal self-view in between episodes. Controversy
The diagnosis of childhood bipolar disorder is controversial, although it is recognized that bipolar disorder typical symptoms are dysfunctional and have negative consequences for minors with the condition. Main discussion is centered on whether what is called bipolar disorder in children refers to the same disorder than when diagnosing adults, and the related question on whether adults criteria for diagnosis are useful and accurate when applied to children.