Pure high-grade fetal adenocarcinoma of the lung: a case report.

BACKGROUND: Pure high-grade fetal adenocarcinoma of the lung (H-FLAC) is a very rare tumor.

CASE PRESENTATION: An annual check-up revealed an abnormal shadow in the left middle lung field of a 63-year-old Japanese man. Chest computed tomography (CT) showed a 3.6 × 2.8 cm pulmonary lesion with clear boundary in the left upper lobe. A transbronchial lung biopsy revealed non-small cell carcinoma. A left upper lobectomy and mediastinal lymph node dissection were performed. Histologically, the tumor consisted of solid proliferation of atypical cell with clear cytoplasm. Another histological component and morulae were not contained. Immunohistochemically, the tumor was focally positive for alpha-fetoprotein (AFP) and beta-catenin in the cell membrane. Accordingly, we made the diagnosis of pure H-FLAC, pT2aN2M0, stage IIIA. Two courses of adjuvant chemotherapy (cisplatin and vinorelbine) were administered but then the treatment was discontinued due to the patient's adverse reaction. At 25 months after the surgery, the patient had relapsed.

CONCLUSIONS: We report a very rare case of pure H-FLAC. This histology has been considered to predict an extremely poor prognosis; therefore, the elucidation of genetic abnormalities and effective treatment is awaited.