Clear Cell Sarcoma-Like Tumor of the Gastrointestinal Tract.

Clear cell sarcoma-like tumor of the gastrointestinal tract (CCSLGT) is a rare and relatively recently described entity. Here, we report a CCSLGT arising in the ileum of 28-year-old man. Histologically, the tumor composed of uniform, epithelioid or spindle cells that have eosinophilic cytoplasm and round, vesicular nucleus with single prominent nucleolus arranged in nests. No melanin pigment is identified. Lymph nodes and liver revealed metastasis. Immunohistochemically, tumor cells labeled with S100, SOX10, while negative for Cam 5.2, HMB-45, A103, CD117, DOG-1, SMA, desmin, chromogranin and synaptophysin. Fluorescence in situ hybridization (FISH) analysis identified rearrangement of EWSR1 (22q12) gene and targeted next generation sequencing revealed characteristic EWSR1 - ATF1 fusion. The patient received systemic chemotherapy and is alive after eight months. CCSLGT should be kept in mind for any tumor arising from the wall of the gastrointestinal tract with epitheloid or spindle cell population that shows S100 expression and lack of melanocytic differentiation.