TY - JOUR AB - Malignant gastrointestinal neuroectodermal tumors (GNETs), also called clear‑cell sarcoma‑like tumors of the gastrointestinal tract, are rare and highly aggressive tumors originating in the gastrointestinal tract. These tumors are generally immunohistochemically positive for S‑100 protein (S‑100) and SRY‑related HMG‑box 10 (SOX10), and often contain EWSR1‑ATF1 or EWSR1‑CREB1. The histological features of GNETs overlap with those of clear‑cell sarcoma of the tendons and aponeuroses. However, GNETs immunohistochemically lack melanocyte‑specific markers and often demonstrate positivity for CD56, synaptophysin and neuron‑specific enolase. The present case reports a woman with a history of desmoplastic malignant melanoma exhibiting a BRAF mutation, which later transformed into a GNET of the small intestine with both a BRAF mutation and two subtypes of EWSR1‑ATF1 fusion genes. Tumor cells were revealed to be weakly immunoreactive or negative for S‑100 and SOX10, lacked markers of melanocytic differentiation and were focally positive for CD56. Combination therapy with dabrafenib mesylate and trametinib dimethyl sulfoxide proved to be temporarily effective against this tumor. The present case is relatively unique as, to the best of our knowledge, there is no case of GNET with a history of melanoma. Furthermore, there is no report of GNET exhibiting both a BRAF mutation and an EWSR1‑ATF1 fusion gene. Further accumulation of similar cases is necessary to elucidate the pathological significance of this GNET having a BRAF mutation. AD - Department of Outpatient Chemotherapy, Osaka International Cancer Institute, Osaka 541‑8567, Japan Department of Diagnostic Pathology and Cytology, Osaka International Cancer Institute, Osaka 541‑8567, Japan Department of Clinical Laboratory, Osaka International Cancer Institute, Osaka 541‑8567, Japan Department of Orthopedic Surgery, Osaka International Cancer Institute, Osaka 541‑8567, Japan AU - Yagi,Toshinari AU - Nagata,Shigenori AU - Yamamoto,Takashi AU - Wakamatsu,Toru AU - Imura,Yoshinori AU - Tamiya,Hironari AU - Sabe,Hideaki AU - Yamashita,Katsunari AU - Takenaka,Satoshi DA - 2021/02/01 DO - 10.3892/mco.2020.2185 IS - 2 JO - Mol Clin Oncol KW - malignant gastrointestinal neuroectodermal tumor clear cell sarcoma‑like tumor of the gastrointestinal tract malignant melanoma BRAF EWSR1‑ATF1 dabrafenib mesylate trametinib dimethyl sulfoxide PY - 2021 SN - 2049-9450 2049-9469 SP - 23 ST - Malignant gastrointestinal neuroectodermal tumor with BRAF mutation and a history of malignant melanoma: A case report T2 - Molecular and Clinical Oncology TI - Malignant gastrointestinal neuroectodermal tumor with BRAF mutation and a history of malignant melanoma: A case report UR - https://doi.org/10.3892/mco.2020.2185 VL - 14 ER -