Background <p>Pulmonary mucinous cystadenoma with ovarian-like stroma has rarely been reported. To the best of our knowledge, only two prior cases have been reported to date.</p> Case presentation <p>A 47-year-old female underwent an ¹⁸F-fluorodeoxyglucose(FDG) positron emission tomography/computed tomography(PET/CT) scan, revealig multiple solid and cystic nodules with mild FDG uptake in both lungs. The tumor exhibited an adenoid or papillary structure, covered by monolayer mucous columnar epithelium and pseudostratified ciliated columnar epithelium, with abundant mesenchymal cells. Nuclei were oval, fusiform, or polygonal, resembling ovarian-like stroma, and showed mild nuclear atypia without atypical mitoses. Immunohistochemical analysis indicated: CK (epithelial cell +), P63 (epithelial basal cells +), CK7 (epithelial cell +), CK20 (−), TTF-1 (epithelial cell +), napsin A (partial epithelial cell +), α-inhibin (−), S100 (−), SMA (−), EMA (epithelial cell +), CEA (−), WT-1 (mesenchymal cells +), ER (mesenchymal cells +), P16 (partial mesenchymal cells +), CD10 (mesenchymal cells +), and Ki-67 (2% +).</p> Conclusion <p>Pulmonary mucinous cystadenoma with ovarian-like stroma is rare, and its pathological nature and classification are not yet fully understood.</p>