Papillary Renal Cell Carcinoma With “Drop Metastasis” (Tumor Seeding) Involving the Distal Ureter

Abstract

A man in his 50s underwent a right nephroureterectomy for multifocal kidney masses. Gross pathologic examination revealed 3 renal masses, the largest measuring 10.0 cm. In addition, a separate tumor was identified within the distal ureter. Histopathologic examination revealed multifocal involvement of the right kidney by papillary renal cell carcinoma, characterized by the presence of tightly packed fibrovascular cores (Figure 1A). Furthermore, focal areas showed a transition to a mesenchymal/sarcomatoid component (Figure 1B), which is typically associated with aggressive clinical behavior.