Primary Ovarian Pleomorphic Adenoma of Salivary Gland Type: Report of A Unique Case With A HMGA2::WIF1 Fusion.

We report a unique case of a primary ovarian neoplasm with morphological and immunohistochemical features identical to a pleomorphic salivary adenoma in a 56-year-old female. Morphologically the tumour was composed of cellular nodules of bland glands lined by a double cell layer of epithelial and myoepithelial cells; cartilaginous elements were also present with focal osseous and bone marrow metaplasia. No teratomatous elements were present. Immunohistochemistry confirmed the presence of a double layer of epithelial and myoepithelial cells (S100, p40, p63, SOX10, calponin and smooth muscle actin positive) and showed diffuse nuclear positivity of both cell types for HMGA2. A HMGA2::WIF1 fusion was identified on molecular testing; this fusion is found in some pleomorphic salivary adenomas. As far as we are aware, this is the first report of a pleomorphic adenoma of salivary gland type within the ovary. We speculate on the histogenesis and review "salivary gland-type" neoplasms arising within the ovary.