Eosinophilic solid and cystic renal cell carcinoma with aggressive behavior: Two case reports

Abstract

BACKGROUND

Eosinophilic solid and cystic (ESC) renal cell carcinoma (RCC), a unique and emerging subtype of RCC, has an indolent nature; in some rare instances, it may exhibit metastatic potential. Current cases are inadequate to precisely predict the clinical outcome of ESC RCC and determine treatment choices.

CASE SUMMARY

Herein, we report two patients with ESC RCC. Patient 1 was a young woman with classical pathological characteristics. Patient 2 was a 52-year-old man with multifocal metastases, involving the pulmonary hilar and mediastinal lymph nodes, liver, brain, mesosternum, vertebra, rib, femur, and symphysis pubis. Awareness of ESC RCC, along with its characteristic architecture and immunophenotype, would contribute to making a definitive diagnosis, even on core biopsy samples.

CONCLUSION

The discovery of ESC RCC molecular signatures may provide new therapeutic strategies in the future.

Keywords: Eosinophilic solid and cystic renal cell carcinoma; Solid and cystic growth pattern; CK20; TSC1 mutations; TSC2 mutations; Case report

Core Tip: Most patients with eosinophilic solid and cystic (ESC) renal cell carcinoma (RCC) have an indolent nature, but 8 cases have exhibited metastatic potential. In this study, we made a clear diagnosis in 2 cases of ESC RCC, including a case with multifocal metastases, by pathological microscopy, immunohistochemistry, next-generation sequencing, or whole exome sequencing analysis, which played a crucial role in clinical treatment. Usually, ESC RCC has a solid and cystic growth pattern, a voluminous eosinophilic cytoplasm with coarse basophilic stippling, is CK20 positive and has TSC1/2 mutations.