Adenocarcinoma of the Lung Metastatic to the Ovary With a Signet Ring Cell Component.

A nonsmoker 45-year-old woman, presented with a solid right ovarian mass. Microscopic examination revealed heterogeneous histology with tubular formations and extensive signet ring cell component that resembled the usual appearance of metastatic gastric carcinoma to the ovary. Moreover, the histology also showed solid nests of cells with a microvacuolated basophilic cytoplasm similar to those found in adenosquamous cervical carcinoma of glassy cell type. However, analysis of the patient's past history revealed a lung adenocarcinoma, diagnosed 4 years before, which prompted an immunohistochemical differential diagnosis, showing a strong expression for TTF-1 and Napsin A. A cervical primary was excluded taking into account both macroscopic findings and the negative expression of PAX8 and absence of human papillomavirus-related marker p16. This confirmed the pulmonary origin of ovarian tumor despite its heterogeneous morphology. This is the first reported case of ovarian metastatic lung adenocarcinoma, with a signet ring cell component and solid nests, mimicking both metastatic gastric carcinoma and adenosquamous carcinoma of glassy cell type.