Eyelid Sebaceous Carcinoma and HER2 expression

Abstract

Purpose : Sebaceous Carcinoma (SC) is an aggressive malignancy that occurs mainly in the periocular region and is usually associated with a high risk of recurrence or metastatic disease. Human epidermal growth factor receptor 2 (HER2) is a proto-oncogene encoded by ERBB2 on chromosome 17. Overexpression of HER2 occurs in several types of cancer, particularly in breast (BC) and gastric carcinomas (GC). We studied the expression of HER2 in eyelid SC and discuss the possible different methods of interpretation for HER2 in SC.

Methods : A total of 18 cases of eyelid SC were evaluated for HER2 expression using a monoclonal antibody and the fully automated Ventana immunostaining system. HER2 expression was evaluated using 0 to 3+ scoring according to the membranous staining pattern in archival formalin-fixed, paraffin-embedded SC. The slides were digitalized and the Aperio software for imaging analyzes was used to evaluate the percentage and pattern of staining. The SC cases were classified in negative, equivocal or positive according to the system of HER2 expression in BC and GC biopsy.

Results : Six (33.3%) out of the 18 cases were classified as equivocal and the 12 (66.7%) remaining cases as negative according to the GC biopsy HER2 score classification. However, according to the BC classification, only 1 case (5.5%) was considered equivocal and 17 cases (94.5%) were classified as negative. The 6 equivocal cases (GC biopsy classification) showed a 3+ or 2+ membranous staining ranging from 1% to 22% of the SC cells.

Conclusions : Our results showed that the rate of HER2 positivity in SC varies according to the different system of classification applied. A new and unique system of HER2 classification for SC should be determined. The highly malignant natural course of SC may require testing the potential therapeutic benefits of anti-HER2 drugs against SC in selected patients.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.