Esophageal basaloid squamous cell carcinoma (EBSCC) is a rare type of esophageal squamous cell cancer (ESCC) characterized by basaloid features and considered to be more aggressive than ESCC. RNA sequencing was performed from 20 pure EBSCC and 11 poorly differentiated ESCC samples; researchers identified chondroitin sulfate proteoglycan 4 (CSPG4) as a potential marker of EBSCC at the mRNA level, which was verified by immunohistochemistry in these same samples.