December 2019 — Genitourinary
A 12 week old boy presented with a 6 cm heterogeneous solid mass with cystic change, involving the mid/lower pole of the right kidney. Grossly, the tumor was soft and hemorrhagic with cystic degeneration.
Figure 1. Interface of the tumor and normal renal parenchyma is sharply demarcated.
Figure 2. The tumor is densely cellular with sheets and vague fascicles of plump spindle cells and focally hemangiopericytoma-like vessels are seen.
Figure 3. Immunohistochemistry for pan-trk with weak to moderate cytoplasmic and nuclear staining.
Figure 4. FISH for ETV6 using dual-color break-apart probe technique
C. Eric Freitag, M.D. Fellow, Surgical Pathology Mayo Clinic @CEFreitagMD
Sounak Gupta, M.B.B.S., Ph.D.Consultant, Anatomic Pathology Mayo Clinic Assistant Professor of Pathology Mayo Clinic College of Medicine and Science