Clear Cell Sarcoma-Like Tumor of the Gastrointestinal Tract, Presenting as a Second Malignancy after Childhood Hepatoblastoma
Figure 1
(a) Clear cell sarcoma-like tumor of the gastrointestinal tract (CCSLGT). Low power view shows diffuse infiltration of the wall of the small bowel completely destroying the muscularis propria and with obliteration of the intestinal mucosa leaving just a thin strip of epithelium overlying each of the villi. (b) The tumor comprises sheets and vague nests of epithelioid or ovoid cells which show moderate nuclear atypia and amphophilic or clear cytoplasm. The nests are much more ill defined than those seen in conventional soft tissue clear cell sarcoma of tendons and aponeuroses. (c) At higher power, the cells show medium sized ovoid to occasionally spindled vesicular nuclei and often small nucleoli. There are prominent mitotic figures. Here, the cells are present in a diffuse sheet-like pattern without discernible nested architecture. (d) There is diffuse nuclear and cytoplasmic expression of S100 protein. S100 protein expression without staining for melanocytic markers is typical of CCSLGT, although some cases may show patchier S100 protein immunoreactivity. Note the diffuse infiltration of the small bowel muscularis propria and tumor proximity to serosal fat. (e) Metastatic CCSLGT in the patient’s subsequent liver biopsy. The metastatic tumor has similar morphology, although it contains cells with amphophilic cytoplasm and no clear cytoplasm or any nested pattern. The lack of characteristic cytologic or immunophenotypic features and the lack of familiarity of pathologists with this neoplasm can understandably lead to confusion with other metastatic tumors with epithelioid or ovoid cell morphology. (f) Diffuse S100 protein expression is also present in the liver metastasis.
