Clear cell (tubulo)papillary renal cell carcinoma (CCTPRCC) is a recently-recognized tumour that shares morphologic features with both clear cell renal cell carcinoma (CCRCC) and papillary renal cell carcinoma (PRCC) but behaves in a more indolent fashion.

4% of renal cell carcinoma, historically most often mistaken for CCRCC. First described in the setting of end stage renal disease, but now known to be most frequently recognized and encountered in a sporadic setting

Patients are usually asymptomatic as these tumors are often small and incidentally found. 

Well-defined and well encapsulated small tumor with frequent cystic formation; usually solitary and unilateral, but multifocality and bilaterally have been reported.^1-3

Characteristic histology includes: branched tubular structures, straight nuclear alignment (picket fence nuclei) above the basement membrane, variable papillary structures protruding into cystic spaces, and low nuclear grade (Fig.1A); an associated fibrous capsule and/or fibromuscular stroma may be present in a subset of cases

Strong, diffuse positivity for cytokeratin (CK) 7, and absence of racemase (AMACR) and a cup-like staining pattern for carbonic anhydrase (CA) IX, which has been thought to be unique to this entity (Fig.1B) 

Fig 1 : Clear cell tubulopapillary renal cell carcinoma (CCTPRCC) is a low grade neoplasm characterized by tubulopapillary architecture (a predominant tubular architecture is shown in the left image), a ‘picket fence-like’ arrangement of the nuclei, and clear cytoplasm (A). Carbonic anhydrase IX (CA9) expression (right) shows a characteristic ‘cup-like’ staining pattern (B).

Indolent tumor with good clinical outcomes, without any recurrences, metastases, or lymph node involvement .⁴

• Combine FISH data, NGS data and virtual karyotyping by SNP array demonstrated minimal genetic variability in this tumor, with normal status of VHL gene (methylation, LOH 3p, mutations) .^5-8

• Some somatic mutaciones, as MET, PTEN, ERBB4, and STK11, have been identified , and RNA profiling revealed overexpression of miR-200 family, distinct from those in other renal tumors ²