




These aggressive neoplasms tend to arise in the muscularis propria
of the ileum of young adults. Spread to the liver and other sites is common and
there is poor response to current therapy.
They can have a nested or pseudopapillary pattern. The pitfall is that they
are easy to mistake for well-differentiated neuroendocrine tumors owing to
their proclivity to express synaptophysin. Keratin expression, however, is
absent and they are strongly reactive for S100 protein. Some examples, such as this one, feature
macronucleoli, which makes their morphology similar to that of clear cell
sarcoma of soft tissue. Most such gastrointestinal
tumors harbor
EWSR1-CREB1 gene
fusions and lack expression of markers of melanocytic differentiation whereas
soft tissue clear cell sarcomas usually have
EWSR1-ATF1 rearrangements and stain with melanoma markers.
References;
1: Antonescu CR, Nafa K, Segal NH, Dal
Cin P, Ladanyi M. EWS-CREB1: a recurrent variant fusion in clear cell
sarcoma--association with gastrointestinal location and absence of melanocytic differentiation. Clin
Cancer Res. 2006 Sep 15;12(18):5356-62.
2: Stockman DL, Miettinen M, Suster S,
Spagnolo D, Dominguez-Malagon H, Hornick JL, Adsay V, Chou PM, Amanuel B,
Vantuinen P, Zambrano EV. Malignant gastrointestinal neuroectodermal tumor:
clinicopathologic, immunohistochemical, ultrastructural, and molecular analysis
of 16 cases with a reappraisal of clear cell sarcoma-like tumors of the
gastrointestinal tract. Am J Surg Pathol. 2012 Jun;36(6):857-68.
3: Green C, Spagnolo DV, Robbins PD,
Fermoyle S, Wong DD. Clear cell sarcoma of the gastrointestinal tract and
malignant gastrointestinal neuroectodermal tumour: distinct or related
entities? A review. Pathology. 2018 Aug;50(5):490-498.