Abstract
Purpose :
Merkel cell carcinomas (MCCs) are rare malignant skin tumors including those affecting the ocular adnexa, and are often associated with Merkel cell polyomavirus (MCPyV) infection. This study investigated the prevalence of MCPyV in and clinicopathological characteristics of eyelid MCCs, and compared the MCPyV status with that of other malignant eyelid tumors.
Methods :
Ten patients diagnosed with eyelid MCC were evaluated. Histopathological features were assessed by immunohistochemical staining with 12 antibodies. MCPyV association was determined by polymerase chain reaction (PCR) targeting the large T antigen of the MCPyV genome, and immunohistochemistry (IHC) using CM2B4 and Ab3 monoclonal antibodies. Additionally, MCPyV viral load was quantified using three distinct primer sets (sT, LT4, and Taq). The IHC distribution of MCPyV was then compared between eyelid MCCs and other malignant eyelid tumors.
Results :
The 10 patients with MCC (4 males and 6 females) were Japanese, with mean age of 79 (range: 63 to 87) years. During a median follow-up of 22 months, one patient died from distant metastasis 8 months after surgery for MCCs. Immunohistochemical analysis showed typical MCC findings including CK20 and neuroendocrine marker positivity, and PCR and IHC detected MCPyV antigens in all MCC samples. When MCPyV antigen expression was compared between tumor cells and non-tumor cells in the same sample, strong staining of MCPyV antigen in tumor cells was observed in All MCC samples, while weak staining in tumor cells was detected in 2 (25%) SC samples, 1 (11%) SCC sample, and 8 (89%) BCC samples. In non-tumor cells of all samples, MCPyV antigen was detected in 41 of 44 (93%) samples, mainly in lymphocytes and epithelial cells of the hair follicle region. Quantitative PCR detected MCPyV genes in all samples, but significantly higher MCPyV gene copies were expressed in MCCs than in non-MCC tumors and controls (p < .0001 for sT, LT4, and TAq).
Conclusions :
This study revealed the clinicopathological characteristics of patients with eyelid MCCs, and the distribution of MCPyV antigens in these tumors. A higher prevalence and higher viral load of MCPyV were detected in all eyelid MCC samples examined. These findings provide insights into the tumorigenesis of eyelid MCCs.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.