Epidermoid cyst of the spleen: a cytokeratin profile with comparison to other squamous epithelia.

The stratified squamous epithelium of a splenic epidermoid cyst was studied with a battery of monoclonal antibodies to cytokeratin (CK) proteins. CKs 10 and 11 were found in the suprabasal layers of the stratified squamous epithelium, while staining for CK 13 was focal or diffuse throughout. CKs 18 and 19 decorated individual squamous cells or stained the entire thickness of the epithelium. These results were compared with those previously obtained by us in stratified squamous epithelia of ovarian mature cystic teratoma, fetal epidermis, adult epidermis and squamous metaplasia in a peritoneal cyst. From these comparisons it emerges that the epidermoid splenic cyst is either of teratomatous derivation or originates from inclusion of fetal squamous epithelium. Squamous metaplasia of mesothelium or inclusions of mature squamous epithelium appears to be an unlikely source of origin of these cysts.