AUTHOR=Qiu Ying , Liu Wenyao , Jin Qianxiu , Sun Xiangjun , Wang Yilin , Zhang Naichun 
  
TITLE=Analysis of clinical and pathological characteristics of 10 cases of fetal lung adenocarcinoma
  
JOURNAL=Pathology and Oncology Research
  
VOLUME=Volume 32 - 2026
  
YEAR=2026
  
URL=https://www.por-journal.com/journals/pathology-and-oncology-research/articles/10.3389/pore.2026.1612579
  
DOI=10.3389/pore.2026.1612579
  
ISSN=1532-2807
  
ABSTRACT=BackgroundFetal adenocarcinoma of the lung (FLAC) is a rare subtype of lung adenocarcinoma resembling the developing fetal lung at the pseudoglandular stage (8–16 weeks of gestation). This study investigates the clinicopathological features, along with key diagnostic and treatment considerations for FLAC.MethodsClinical data from 10 FLAC patients diagnosed at Linyi People’s Hospital between January 2017 and December 2024 were retrospectively analyzed. Their clinicopathological characteristics were summarized in conjunction with relevant literature.ResultsThe cohort comprised low-grade FLAC (L-FLAC, 6 cases) and high-grade FLAC (H-FLAC, 4 cases). Pathological examinations indicated higher frequencies of pleural invasion (3/4) and lymph node metastasis (1/4) in H-FLAC, which exhibited marked nuclear atypia and abundant mitoses, while L-FLAC demonstrated mild cellular atypia and morular structures. Immunohistochemistry revealed universal positivity for TTF-1. Napsin A expression was noted in both L-FLAC (3/3) and H-FLAC (2/4). In L-FLAC, β-catenin showed nuclear/cytoplasmic or nuclear expression in the vast majority of cases while H-FLAC displayed only membranous expression. Molecular testing detected an EGFR exon 19 deletion in one H-FLAC case and a KRAS G12C mutation in another. No recurrence was observed during follow-up, which ranged from 4 to 93 months.ConclusionFLAC exhibits distinctive morphological features and immunophenotypes, necessitating differential diagnosis from primary pulmonary tumors and metastatic malignancies. Surgical resection remains the primary therapeutic strategy. No disease recurrence was observed during follow-up from 4 to 93 months, although some patients had a shorter follow-up period of 4–6 months.