Periocular intraepithelial sebaceous neoplasia: critical appraisal of nomenclature and prognostic importance.

Intraepithelial sebaceous neoplasia in the forms (or subclassification) of pagetoid spread and carcinoma in situ is a common feature of periocular sebaceous carcinoma and is associated with less favourable outcomes. Seminal studies of periocular sebaceous carcinoma in the 1980s indicated that the two patterns of intraepithelial spread had differing influences on prognosis with pagetoid invasion being worse. Later studies reported conflicting results, but careful inspection of those studies revealed considerable variation in what was meant by pagetoid invasion. Different interpretations of pagetoid spread continue, leading to ambiguous results in clinical studies and miscommunication with potential unintended decisions affecting clinical management. This paper reviews the background leading to the frequent interchangeable use of pagetoid spread with in situ sebaceous carcinoma and how this problem confounds interpretation of clinical studies. The author recommends that for effective communication, all morphological patterns of in situ spread of sebaceous carcinoma fall under the term intraepithelial sebaceous neoplasia, which can be accompanied by subclassification whenever desired.