We report a case of
clear cell sarcoma (CCS) in the left buttock in which serum
neuron-specific enolase (NSE) was useful as a
biomarker of CCS progression. A 40-year-old man had a subcutaneous
tumor, 1.7 cm in diameter, in the left buttock. Histopathology revealed that the
tumor consisted of nests of polygonal or spindle-shaped cells with abundant clear cytoplasm delineated by fibrous septa in the subcutaneous tissue. There was cellular atypia but no
melanin deposits. Immunohistochemically, the
tumor cells were positive for HMB-45,
Melan-A,
S-100 protein and NSE. Reverse transcription polymerase chain reaction demonstrated
Ewing's sarcoma oncogene-
activating transcription factor 1 fusion transcripts in the
tumor cells. CCS was diagnosed. There was no
metastasis to the lymph nodes and viscera, and the patient was treated by surgical wide resection. The serum NSE levels increased before detection of distant
metastasis and further increased in parallel with the expansion of
metastasis. The present case suggests that serum NSE could be used as a
biochemical marker in the clinical follow up of patients with CCS.