SMARCB1‐deficient renal medullary carcinoma with an EML4::ALK fusion gene in a Japanese woman

Abstract Renal medullary carcinoma is a rare, high‐grade carcinoma arising in the renal medulla, which is usually associated with sickle cell trait, and there are very few documented cases in the Japanese population. We report a case of renal medullary carcinoma, immunohistochemically defined as SMARCB1 deficient, in a 67‐year‐old Japanese woman without a history of sickle cell trait. Somatic mutation of SMARCB1 and an EML4 :: ALK fusion gene were identified by comprehensive genomic profiling. Computed tomography revealed metastatic lesions in the retrocaval lymph nodes, liver, and bronchus. Six cycles of the dose‐dense methotrexate, vinblastine, adriamycin, and cisplatin‐combined chemotherapy were completed after an ultrasound‐guided percutaneous biopsy of the renal tumor. After chemotherapy, the size of the original tumor in the right kidney had decreased in size, as well as the other metastatic lesions.