Case 103 - Discussion

Uploaded: 2007-09-27, Updated: 2007-09-27



CK7 Synaptophysin




The tumor shows biphasic feature, which includes small cell carcinoma and squamous cell differentiation.  The immunohistochemical stains show both small cell and squamous cell component, positive for TTF-1and negative for CK20. However, the small cell component is positive for synaptophysin, weakly positive for chromogranin but is negative for CK7.  The squamous cell differentiation component is negative for neuroendocrine markers synaptophysin and chromogranin but, is positive for CK7. 

Combined small cell carcinoma is a relatively rare entity and the behavior of this tumor is more like that of a typical small cell carcinoma, not a squamous cell malignancy.