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* Clear cell sarcoma-like tumor of the gastrointestinal tract (CCSLGT) is a rare malignant neoplasm that occurs in the wall of the small bowel, stomach, or large bowel, predominantly in young adults. It is an aggressive neoplasm that frequently presents with metastatic disease and has a high mortality rate. Histologically, it is usually composed of medium-sized primitive ovoid or epithelioid cells with pale or clear cytoplasm that are arranged in sheets or in papillary or alveolar architectures. Clear cell sarcoma-like tumor of the gastrointestinal tract is positive for S100 protein, invariably negative for melanocytespecific markers and is often also positive for neuroendocrine markers. The etiology of CCSLGT is unknown, but many studies have shown associations with EWSR1-CREB1 gene fusions and, less frequently, with EWSR1-ATF1 fusions. Here, we discuss the current status of CCSLGT, including histologic, immunophenotypic, and molecular findings.
(Arch Pathol Lab Med. 2015;139:407-412; doi: 10.5858/ arpa.2013-0547-RS)
Clear cell sarcoma-like tumor of the gastrointestinal tract (CCSLGT; osteoclast-rich tumor of the gastrointestinal tract with features resembling clear cell sarcoma [CCS] of softparts) is a rare malignant neoplasm that arises within the wall of the small bowel, stomach, or large bowel, and predominantly occurs in young adults.1-3 Clear cell sarcoma- like tumor of the gastrointestinal tract was first described as a distinct entity in 2003 in a series of 6 cases by Zambrano et al.3 However, cases that may be morphologically similar to CCSLGT have been reported previously, including by Alpers and Beckstead,4 who reported a ''malignant neuroendocrine tumor of the jejunum with osteoclast-like tumor giant cells'' in 1985. To our knowledge, only 38 cases have been published,1,2,5-14 of which 9 are single case reports and 5 are cases series, with the largest describing a cohort of 16 patients.
Clear cell sarcoma-like tumor of the gastrointestinal tract is often difficult to distinguish from conventional CCS (of softtissue or of tendons and aponeuroses) because their morphologic features overlap, they both express S100 protein, and they both can harbor identical genetic abnormalities, but in contrast to CCS, CCSLGTs lack immunohistochemical or ultrastructural evidence of melanocytic differentiation. Clear cell sarcoma (previously known as melanoma of softparts) is a longer-established and better-recognized entity that was first described in 1965 by Enzinger.15 Clear cell sarcoma occurs in young to middleaged adults,...