Renal mixed epithelial and stromal tumour

Definition

This is a rare tumour, most often occurring in women, a number of whom are receiving hormone replacement therapy. Similar tumours have probably been reported as "cystic hamartoma of the pelvis"3 and as "adult mesoblastic nephroma"2.

Macroscopic appearances

The tumour is often located in the renal pelvis. It forms a well-circumscribed mass with solid and cystic areas.

Histopathology

There is a mixture of bland spindle cells and epithelial elements tubular forming tubules and cysts.

Immunohistochemistry

Differential diagnosis

• sarcomatoid renal cell carcinoma.

• metanephric adenofibroma: occurs in children and young adults. The epithelial element is identical to that in metanephric adenoma. The spindle cell component is negative for actin and desmin.

• angiomyolipoma (HMB45+) with entrapped tubules

• nephroblastoma: includes a blastemal element.

• monophasic spindle cell tumours such as leiomyoma and solitary fibrous tumour (CD34+).

Prognosis

The few cases reported have been benign.

References

1Adsay, N. V., J. N. Eble, et al. (2000). "Mixed epithelial and stromal tumor of the kidney." Am J Surg Pathol 24(7): 958-70.

2Nagao, T., I. Sugano, et al. (1999). "Cystic partially differentiated nephroblastoma in an adult: an immunohistochemical, lectin histochemical and ultrastructural study." Histopathology 35(1): 65-73.

3Pawade, J., G. N. Soosay, et al. (1993). "Cystic hamartoma of the renal pelvis." Am J Surg Pathol 17(11): 1169-75.

This page last revised 6.1.2004.

©SMUHT/PW Bishop