Abstract 3387: Mutational analysis in metastatic melanoma to the breast and ovary: correlation with clinic-pathological and immunohistochemical findings

Abstract Metastatic malignant melanoma or stage IV melanoma is the most deadly skin cancer, claiming an estimated 10,000 deaths every year. The occurrence of metastatic malignant melanoma to the breast and ovary is uncommon, and can represent a challenge for the diagnosis and clinical management. We investigated and correlated the morphologic, immunohistochemical and molecular aspects of these tumors. Morphologic analysis of the cases revealed a predominance of epithelioid pattern, and few of these were associated with more spindle cell areas. Most of the tumor cells aberrantly expressed high levels of PD-L1, especially in the metastatic melanoma to the breast. Other relevant melanoma targets for immunotherapy were also explored by immunohistochemistry. Of note, most of the metastatic tumors were negative for NY-ESO. The mutational analysis of these metastatic lesions, using next generation sequencing for the detection of cancer gene mutations including rare mutations at low frequency, found an heterogeneous mutational landscape, reinforcing the importance of personalized treatments. Mutations in RAS gene family members in these metastatic tumors were the most frequent in our samples, followed by CDKN2A and CTNNB1 mutations. Other less frequent mutations were also detected, including ATM and KIT. Interestingly, one rapidly progressive melanoma metastatic to the breast in a young patient had areas of spindle cell morphology and no common melanoma gene mutations. Overall, our cases illustrate the pathologic and molecular variability of metastatic malignant melanoma to uncommon organs of involvement, such as breast and ovary, and provide novel insights into their diagnostic and clinical management algorithm. Note: This abstract was not presented at the meeting. Citation Format: Alessio Giubellino, Vanessa Moreno, Xu Naizhen, Liqiang Xi, Mark Raffeld, Maria Merino. Mutational analysis in metastatic melanoma to the breast and ovary: correlation with clinic-pathological and immunohistochemical findings [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3387. doi:10.1158/1538-7445.AM2017-3387