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.