[Adult pulmonary blastoma:a case report].

We reported a case of pulmonary blastoma treated with surgical resection, in which we analyzed the clinical features, pathological characteristics, diagnosis, differential diagnosis, treatment, and prognosis. The clinical features, histopathology, and immunohistochemical staining results were observed, along with perioperative adjuvant therapy. The patient, a 21-year-old female, was admitted with the chief complaint of "lung mass discovered during physical examination for over one year." PET-CT revealed a metabolically active soft tissue mass measuring 7.8 cm×8.4 cm in the right lower lobe, with hypermetabolic right hilar lymph nodes suggestive of metastasis. Both biopsy and postoperative pathology confirmed pulmonary blastoma. Immunohistochemistry showed: AE1/AE3 (+), CK7 (-), CK20 (-), TTF-1 (+), NapsinA (focal+), SALL4 (+), ER (-), Desmin (-), MyoD1 (-), S-100 (focal+), B-Catenin (+), SYN (partial+), CgA (focal+), Ki-67 (40%+). Grossly, the tumor presented as an oval-shaped, grayish-yellow mass measuring 8.5 cm×6.8 cm×6.0 cm, with a brittle texture and relatively well-demar boundaries from surrounding tissues. Bronchial margins and pleura were not involved. Microscopically, the tumor consisted of varying proportions of epithelial and mesenchymal components. The epithelial component typically exhibited low-grade embryonic-type adenocarcinoma morphology, with morule-like squamous cell nests. The stromal cells displayed primitive mesenchymal morphology. The patient achieved a favorable outcome after comprehensive treatment consisting of neoadjuvant immunochemotherapy, radical surgery, and adjuvant immunotherapy maintenance. Pulmonary blastoma is a rare and highly malignant lung tumor. It should be distinguished from carcinosarcoma, adenocarcinoma, and other lung neoplasms. The primary treatment is surgical resection. Chemotherapy and immunotherapy should be considered as potential therapeutic strategies for pulmonary blastoma.