Pagetoid Bowen Disease: A Simulator of Clonal Seborrheic Keratosis, Case Report

Seborrheic keratosis (SK) and Bowen disease (BD) are different entities in dermatopathology. Differentiating between these two is important and can sometimes be a challenge for the pathologist, who may need to rely on complementary techniques. To obtain a reliable distinction, several immunohistochemistry markers have been explored such as p16 and Ki67, being positive in Bowen disease and negative in Seborrheic keratosis. Ki-67 is a non-histone protein associated with ribosomes and a well-known marker of cellular proliferation, overexpressed in Bowen disease. In addition, it has been related to a greater expression of antigens associated with the growth and differentiation of keratinocytes. P16 is a tumor suppressor gene that inhibits cyclin-dependent kinases 4 and 6. His inactivation leads to a unregulated proliferation of the cell cycle. A greater expression was found in Bowen Disease compared to Seborrheic Keratosis. Immunohistochemistry allows the distinction between entities that may be appear similar both clinically and histopathologically. This is of utmost relevance since proper treatment depends on a precise diagnosis.