Heterogeneous response to target therapy in metastatic papillary renal cell carcinoma evaluated by morphologic and metabolic multimodality imaging

Papillary renal cell carcinoma (PRCC) accounts for about 15% to 20% of renal cell carcinoma and is histologically distinguished in type I and type II. The last one is associated with poorer prognosis. Treatment options for PRCC patients are surgery, immunotherapy, revolutionized by Nivolumab, and other target-therapy with an improvement in overall survival. Heterogenous response and a pseudo-progression may be observed in the initial phase of biological treatment that could induce premature discontinuation. Patient concerns: We present the case of a 44-year-old woman with left cervical palpable mass increased in size and without concomitant disease or previous surgery. Diagnosis: Neck ultrasonography, contrast-enhanced Computed Tomography, and 18F-FDG PET/CT were performed with the detection of lymph nodes involvement and a left renal lesion. Interventions: The patients underwent left radical nephrectomy and homolateral cervical and para-aortic lymphadenectomy, with histological diagnosis of PRCC, type II. After disease relapse, the inter-aortocaval lymph node was laparoscopically removed. Following the detection of further disease relapse in several lymph nodes and the lung, several lines of target-therapy were started; then disease progression and worsening of clinical and hematological status led us to start Nivolumab as last-line therapy. Outcomes: A heterogeneous response to therapies was documented with morphological and nuclear medicine imaging, however the concomitant deterioration of performance status and liver function led to discontinuation of Nivolumab; then the patient died, 30 months after diagnosis. Lessons: Here we describe the clinical case and radiological and nuclear medicine imaging investigations performed by our patient, highlighting that 18F-FDG PET/CT shows greater adequacy in assessing the response to therapy, avoiding premature drug discontinuation, and ensuring better management of a patient with advanced PRCC.