High-grade fetal adenocarcinoma of the lung with abnormal expression of alpha-fetoprotein in a female patient: Case report

Abstract

Introduction: Fetal adenocarcinoma of the lung (FLAC) is an extremely rare tumor. Due to its rarity, most of the knowledge about FLAC comes from case reports. FLAC is an invasive adenocarcinoma that is similar to the fetal lung in the pseudo-glandular stage (8-16 weeks of gestation). Owing to the differences in histopathology and clinical process, FLAC has been further divided into low-level (L-FLAC) and high-level (H-FLAC). H-FLAC is usually associated with other conventional types of lung adenocarcinoma. Lung adenocarcinoma that produces alpha-fetoprotein (AFP) is a rare type of lung cancer. Its characteristics have not been fully elucidated.

Patients concerns: We recently encountered this type of FLAC in a 51-year-old female patient. A computed tomography (CT) scan of the chest revealed a 74 × 51-mm sized tumor in the lingual segment of the superior lobe of the left lung. Among the tumor markers, serum AFP was elevated (816.2 ng/mL).

Primary diagnosis, interventions, and outcomes: The diagnosis of FLAC in this patient was confirmed by bronchoscopy with lung biopsy. Through a thoracoscope, left lung pneumonectomy, and mediastinal lymph node dissection were performed. The postoperative pathological results were consistent with the preoperative diagnosis of H-FLAC. Western blotting showed the difference in the AFP expression between the normal lung tissue and the cancerous lung tissue. Eventually, the diagnosis was AFP-producing H-FLAC. Using an immunohistochemical marker for AFP, cancer cells were shown to express AFP, specifically in their nuclei. After the operation, the patient underwent conventional chemotherapy. Her serum AFP gradually decreased over the course of 2 weeks.

Conclusion: Presently, specific tumor markers for the diagnosis of lung cancer have not been established. To the best of our knowledge, this is the first case of abnormal AFP expression in a patient with H-FLAC. It may provide a basis for the clinical diagnosis of H-FLAC, a rare tumor, and AFP may be considered as a specific tumor marker.

Figure 1

Chest computed tomography (CT) scan showing a soft tissue mass in the tongue segment of the left superior lobe of the left lung. Tumor size was approximately 74 × 51 mm, and the CT value was 33 HU. A small liquefaction component was seen in the soft tissue mass.

Figure 2

Hematoxylin and eosin staining of the normal lung tissue and affected lung tissue in patients with high-level fetal adenocarcinoma of the lung. (A) (magnification ×100) and (B) (magnification ×200) show the pathology of the normal lung tissue. (C) (magnification ×100) and (D) (magnification ×200) show the histopathological changes in the affected lung tissue. The tumor consists of complex glandular structures lined with glycogen-rich high columnar cells with obvious nuclear atypia and extensive necrosis.

Figure 3

Levels of alpha-fetoprotein (AFP) in patients with high-level fetal adenocarcinoma of the lung (H-FLAC). Representative bands of AFP in the tumor tissue and normal lung tissue of a patient with H-FLAC. The grayscale values of AFP in the tumor and normal lung tissues were 20,727 ± 8955 ng/mL and 4733 ± 1247 ng/mL, respectively. AFP expression was significantly higher in the tumor tissue than that in the normal lung tissue, wherein AFP was hardly expressed.

Figure 4

Immunohistochemistry of AFP in patients with high-level fetal adenocarcinoma of the lung. The arrangement of atypical cells is similar to that in fetal lungs in the pseudo-adenoid stage, with obvious nuclear atypia. Cancer cells express AFP, which is usually found in the nuclei. Bar = 100 μm. AFP = alpha-fetoprotein.