September 2017 - Presented by Dr. Amir Ghorbani

Clinical History

A 5 week old female presented with blood in her diaper. On examination, she was unremarkable without any evidence of pain, fever, or rash. However, placing a Foley catheter revealed gross hematuria. She was admitted for further work up.


Abdominal ultrasound showed a 3.0 x 2.6 x 2.0 cm hypoechoic mass which appeared to be confined to the central portion of the right kidney (Figure 1).

Abdominal MRI showed a mass which was slightly hyperintense on T2 (Figure 2) and slightly hypointense on T1 (Figure 3). The mass was well-circumscribed and there was no evidence of hydronephrosis or infiltration of surrounding fat.


The patient underwent a right radical nephrectomy. Our pathology lab received a 32.0 g, 5.8 x 3.6 x 3.1 cm nephrectomy specimen. Sectioning revealed a well-demarcated 3.1 x 2.8 x 2.1 cm mass in the middle third of kidney with tan fleshy cut surface and areas of hemorrhage. It was directly beneath the renal capsule but appeared to be confined to the kidney. The remainder of the specimen was unremarkable. (Figure 4)

Microscopic examination showed a well-demarcated highly cellular mass composed of fascicles of plump spindle cells with numerous mitoses. (Figures 5, 6, 7)

FISH testing was positive for ETV6 (12p13.2) rearrangement.

Click image to enlarge

Figure 1         Figure 2
Ultrasound shows a hypoechoic
mass in the right kidney (arrow).
MRI-T2 shows a slightly hyperintense
well-circumscribed mass in the right kidney (arrow).

Figure 3 Figure 4
MRI-T1 shows a slightly hypointense
right renal mass (arrow).
Well-circumscribed solid mass with fleshy
tan cut surface and areas of hemorrhage.

Figure 5 Figure 6
Densely packed spindle cells with
an area of hemorrhage.
Tumor with “pushing” border, dense cellularity.

Figure 7
Densely packed plump spindle cells
with high mitotic rate.

What is the diagnosis?

Choose one answer and submit.


The correct answer is

D. Cellular Congenital Mesoblastic Nephroma

> Learn more about this diagnosis.