Mesoblastic Nephroma - Cellular pattern
Cellular (atypical) mesoblastic nephroma consists of a highly cellular proliferation of atypical spindle cells with brisk mitotic activity. The appearance is similar to that of infantile fibrosarcoma. Indeed both tumors share morphologic as well as genetic abnormalities [t(12;15)(p13;q25) translocation which results in ETV6-NTRK3 gene fusion]. Based on these similarities, it has been suggested that the two tumors may represent the same entity.