Renal cell carcinomas with a mesenchymal stromal component: what do we know so far?

Area of Science:

• Uropathology
• Neoplastic Pathology
• Molecular Oncology

Background:

• A subset of renal cell neoplasms exhibits a mesenchymal stromal component resembling smooth muscle.
• The precise classification and relationship of these tumors, such as renal cell carcinoma with angioleiomyoma-like stroma, remain debated.
• Similarities in immunohistochemical phenotypes with clear cell papillary renal cell carcinoma add to diagnostic complexity.

Purpose of the Study:

• To review the current understanding of renal cell neoplasms with mesenchymal stromal components.
• To discuss the diagnostic challenges and controversies surrounding these entities.
• To highlight the need for further molecular investigation.

Main Methods:

• Literature review of renal cell neoplasms with stromal components.
• Analysis of immunohistochemical and genetic features.
• Discussion of differential diagnoses and pathological entities.

Main Results:

• Renal cell carcinoma with angioleiomyoma-like stroma shows distinct features, including cytokeratin 7 positivity and often lacks clear cell renal cell carcinoma genetic alterations.
• Some smooth muscle-rich renal cancers are associated with tuberous sclerosis complex, while others occur sporadically.
• Recent findings of TCEB1 mutations and chromosome 8 monosomy in some renal cell carcinomas with fibromuscular stroma suggest heterogeneity.

Conclusions:

• Renal cell neoplasms with stromal components represent a heterogeneous group of entities requiring further molecular characterization.
• Distinguishing these from other renal tumors like clear cell papillary renal cell carcinoma is crucial.
• Understanding the molecular pathology may have implications for inherited tumor syndromes.