Clinical significance of recombinant RANBP2-ALK oncogene to radiotherapy in a case of locally advanced rectal epithelioid inflammatory myofibroblastic sarcoma: case report and review of literature

Epithelioid inflammatory myofibroblastic sarcoma (EIMS) is a highly aggressive variant of inflammatory myofibroblastic tumor (IMT). It is characterized immunohistologically by anaplastic lymphoma kinase (ALK) overexpression and genetic rearrangements in selected cases. The clinical significance of ALK rearrangement on radiotherapy was never reported in EIMS. Here we report a case of locally advanced rectal EIMS. In 2017, a 62-year-old woman was offered laparoscopic abdominoperineal resection for locally advanced EIMS of the rectum. Initial presentation was hematochezia and unintentional body weight loss. The resected tumor was positive for Ran-binding protein (RANBP2)-ALK fusion oncogene. Adjuvant radiotherapy was arranged for microscopic residual disease. Rapid intra-abdominal dissemination and local failure were identified shortly after the assigned treatments. She succumbed to the disease 134 days after diagnosis. In the era of precision oncology, the clinical significance of RANBP2-ALK recombination should be recognized. As treatment options are limited at time of treatment failure, upfront ALK inhibitor may be