[1749] P16 and P53 Expression in Periocular Sebaceous Cell Carcinoma

William R Bell, Kamaljeet Singh, Charles G Eberhart. Johns Hopkins University School of Medicine, Baltimore, MD; Brown University, Providence, RI; Wilmer Eye Institute, Johns Hopkins Medical Institutions, Baltimore, MD

Background: Sebaceous carcinoma is a malignant neoplasm which often presents in the periocular region. In the United States, this lesion accounts for 1.3 to 4.7 % of malignant eyelid tumors. Histological diagnosis is often difficult, particularly in small biopsies in which tumor is often present only as scattered cells in the squamous or conjunctival epithelium. Determining the extent of such pagetoid spread can also be difficult in mapping biopsies or at margins of larger resections. The goal of this study was to evaluate p53 and p16 as potential immunohistochemical markers of sebaceous carcinoma, particularly intraepithelial tumor, in the ocular adnexa.
Design: Sebaceous carcinoma specimens were retrieved from the pathology archives of our institution, including 20 primary and 13 recurrent tumors. All tissues were fixed in 10% buffered formalin, routinely processed and paraffin embedded. Immunohistochemistry was performed using 5-μm sections and a Leica autostainer(Leica)for P16(Cintec)and a Ventana XT autostainer(Ventana Medical Systems)for P53(Ventana).
Results: We found 48% of the periocular sebaceous carcinoma cases to have intense nuclear p53 immunostaining. Additionally, we found 70% of sebaceous carcinoma of the periocular region to have intense p16 nuclear reactivity. 4 cases showed only strong p53 staining, while 9 cases showed only strong p16 staining. For both markers, immunoreactivity was relatively diffuse both within and between blocks. It was also roughly equivalent in both large subepithelial tumor nodules, and in the intraepithelial portion of the lesions. Together, our series revealed intense immunoreactivity to either p53 or p16 in 95% of cases, and weak or negative immunoreactivity in 5% of cases.
Conclusions: Major pathways implicated in the molecular mechanisms of skin cancer include the p53 and p16 pathways. While the expression of p53 has previously been examined as a potential marker of sebaceous carcinoma, p16 has not been well studied. Our findings confirm expression of p53 in a significant proportion(48%) of periocular sebaceous carcinoma. We found that an even greater proportion of tumors(70%) had intense p16 nuclear reactivity, suggesting that it could represent an additional marker with which to track tumor spread. Because some tumors expressed only p53 or p16, combined staining may represent the most effective way to highlight intraepithelial tumor, with 95% of cases showing immunoreactivity for one of the two markers.
Category: Ophthalmic

Tuesday, March 5, 2013 9:30 AM

Poster Session III # 217, Tuesday Morning


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