Anaplastic Lymphoma Kinase (ALK)-Rearranged Renal Cell Carcinoma: A Case Report Highlighting Diagnostic Challenges...

A 57-year-old male underwent an open right radical nephrectomy in 2015 for a 3-cm kidney tumor which was classified at the time as a combined tubulocystic and collecting duct carcinoma. One of six nodes was positive for metastatic carcinoma and the patient received adjuvant carboplatin/gemcitabine chemotherapy. In 2020, he developed enlarging retroperitoneal adenopathy and underwent a retroperitoneal lymph node dissection with 11 of 13 nodes in the resected specimen positive for the previously described renal carcinoma, followed by adjuvant radiotherapy. In November 2022, he again underwent surgery for further locoregional recurrence with resection of a right psoas mass lesion and right hemicolectomy. Pathology on this occasion was reclassified as anaplastic lymphoma kinase-rearranged renal cell carcinoma (ALK-RCC). Shortly afterward, a restaging CT revealed multiple liver metastases and evidence of further disease recurrence in the right renal bed. He commenced alectinib with a complete radiological response and has continued on it for 12 months at the time of writing this report. To our knowledge, there are only five prior reports of ALK-RCC treated with targeted ALK inhibitor therapy in the literature. We report this case to highlight the importance of recognizing and diagnosing this rare RCC subtype since it has significant therapeutic implications. Furthermore, to our knowledge, this patient has had the longest follow-up reported to date in the literature so far. A concerted effort by the histopathology and oncology community is needed to gather more data on the incidence and treatment outcomes of these tumors so that progress can be made in optimizing their management. It is important to consider novel and emerging entities from the most recent WHO 2022 classification, many of which are defined by molecular characteristics with associated therapeutic implications.