Incidental renal mass in a young adult: diagnosis, robotic-assisted treatment and immunohistochemical evaluation - a case report

Introduction and importance: Renal-cell-carcinoma (RCC) is the most common non-Wilms-renal-tumor in pediatric patients, although its incidence remains low. Surgery is the gold standard, however, still limited literature on the optimal approach for young adults. With the increasing experience in robotic-assisted (RA) surgery, this technique represents a promising option. We present a case of RA radical-nephrectomy for a large RCC in a young adult, emphasizing the role of immunohistochemical (IHC) analysis in achieving an accurate histopathological diagnosis. Case presentation: In July 2024, an 18-year-old female was admitted to the ER of Padua Hospital with abdominal pain and fever. A CT scan revealed a 12 x 12 x 13.5 cm mass in the superior pole of the right kidney, cM0. A percutaneous renal biopsy confirmed RCC with an oncocytic pattern. The patient underwent RA radical nephrectomy without postoperative complications. Histological examination revealed a 16 x 10 x 10 cm chromophobe RCC (chRCC), classified as pT2aN0M0 (WHO 2022). IHC analysis showed CK7 and CD117 positivity, confirming the diagnosis. Clinical discussion: RA approach was safe and effective, providing benefits in blood loss, mobilization and pain control. When feasible can be considered even for large renal masses in young adults. ChRCC is rare, characterized by a low recurrence risk and favorable prognosis. Accurate histological and IHC characterization is crucial for diagnosis, as differentiating chRCC from other oncocytic tumors can be challenging. CK7 and CD117 are key markers in establishing a definitive diagnosis. Conclusion: This case represents a successful and safe RA surgery in young adults, emphasizing the importance of IHC in differentiating between histological subtypes.