Details
42 year-old male with a mass at the base of the tongue.
Hyalinizing clear cell carcinoma (HCCC) is a rare minor salivary gland tumour, histo-morphologically characterized by clear cells forming cords/nests in hyalinized stroma. The tumour is considered to be low-grade by definition, and the overall outcome is excellent, with only occasional metastatic spread.
Immunohistochemistry shows diffuse positivity for pan-cytokeratin, p63, and CK5. The biopsy for this case was initially signed out as squamous cell carcinoma (SCC), perhaps based on p63 immunoreactivity. The distinction is of great importance as the management of the two tumours can differ significantly, depending on the extent of the disease.
The presence of t(12;22)(q13;q12)(EWSR1-ATD1) translocation in this tumour allows for definitive diagnosis. This translocation can also be detected in clear cell odontogenic carcinoma (CCOC), an observation leading some to speculate that CCOC and HCCC are related processes.