Metaplastic conversion of the differentiation pattern in oral epithelia affected by leukoplakia simplex. A stereologic study.

The present study applied methods of stereologic cytology to clinically specified lesions of leukoplakia simplex which originated from the oral mucous membrane at the cheek and the floor of the mouth. The data provided the following evidence: (1) The structure of and the differentiation gradients for various cytoplasmic constituents in leukoplakia simplex epithelium were identical at both sites. (2) The differentiation pattern of leukoplakic epithelia was adversely different from that of the respective normal epithelium. (3) This alteration which resulted in a striking resemblance between the leukoplakic epithelia and those of normal skin or hard palatum conceivably can be regarded as a squamous metaplasia characterized by the conversion of one differentiation pattern into another. (4) This shift in the differentiation pattern hardly could have been disclosed by means other than stereologic morphometry.