Lung Metastatic Recurrence as Carcinosarcoma from Ovarian Mesonephric-Like Adenocarcinoma: A Case Report.

Mesonephric-like adenocarcinoma (MLA) is a rare tumor that is typically found in the ovary or uterus, characterized by immunohistochemical positivity for TTF1 (NKX2-1), PAX8, and GATA3, and negativity for estrogen receptor. Although known for its aggressive clinical course with frequent metastases and poor prognosis, MLA metastasizing as carcinosarcoma has not been previously documented. We present a 61-year-old woman with ovarian MLA who exhibited an unusual progression: the tumor recurred in the lung as a carcinosarcoma. Despite intensive chemotherapy and surgical treatment, the patient passed away. Histopathological examination of the lung tumor confirmed MLA features and a KRAS mutation, also found in liver metastases. This report emphasizes the importance of considering a history of ovarian MLA when diagnosing lung tumors and the utility of PAX8 as a diagnostic marker. This is the first reported occurrence of MLA metastasizing as carcinosarcoma, providing new insights into its rare behavior.