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H. Yoshino
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P1.04 - Poster Session/ Biology, Pathology, and Molecular Testing (ID 233)
- Event: WCLC 2015
- Type: Poster
- Track: Biology, Pathology, and Molecular Testing
- Presentations: 1
- Moderators:
- Coordinates: 9/07/2015, 09:30 - 17:00, Exhibit Hall (Hall B+C)
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P1.04-034 - A Case of Fetal Lung Interstitial Tumor (FLIT) in a Neonate (ID 406)
09:30 - 17:00 | Author(s): H. Yoshino
- Abstract
Background:
Fetal lung interstitial tumor (FLIT) is a newly recognized and a rare lung lesion of neonates. The entity was firstly proposed by Dishop MK, et al. in 2010. FLIT is histologically charized by unique mixture of immature interstitial mesenchyme with irregular airspace-like structures, which mimicks abnormal and incompletely developed lung.To date, only 13 cases of FLIT have been reported including 2 cases from Japan. We herein present another case of FLIT in a neonate with histopathological and immunohistochemical analyses to discuss its pathogenesis.
Methods:
not applicable
Results:
A 3 day-old boy was referred to our hospital with respiratory distress. He was born at 36 weeks of gestation, weighing 2070 g. Chest X-ray and computed tomography findings depicted a mediastinal tumor containing viscous fluid. However, the operation revealed that the tumor was developed in the left lung, and the tumor was resected. The postoperative course was uneventful and no recurrent disease was detected at his latest follow-up at 2 years after the resection. The tumor was 30x25x20mm-sized and its cut section showed a well-circumscribed solid and cystic mass. Histological examination revealed a well-circumscribed lesion with a fibrous capsule. The lesion consisted of immature airspace-like structures with widened septa containing immature mesenchymal cells, also, overlaying low cuboidal epithelium was observed. Immunohistochemically, the epithelial cells were positive for cytokeratin, EMA, and TTF-1. The interstitial cells were diffusely positive for vimentin and smooth muscle actin, and negative for desmin. Not nuclear but cytoplasmic staining of beta-catenin was observed in the epithelial cells. The tumor cells were immunohistochemically negative for ALK. The differential diagnoses of the tumor included pleulopulnmonary blastoma (PPB), and congenital cystic adenomatoid malformation/congenital pulmonary airway malformation (CCAM/CPAM) type 3. PPB is characterized by rhabdoid or blastemal cells and/or anaplastic features and CCAM/CPAM type 3 generally shows a diffuse lesion without a capsule.These histological features were not observed in the present tumor, and it was diagnosed as FLIT. Yoshida M, et al. noticed the nuclear stainig of beta-catenin in the epitheliaｌ cells of FLIT. Its nulcear staining is also observed in the epithelai cells in fetal lung at pseudo-glandular stage, and they discussed the resembrance between FLIT and fetal lung at pseudo-glandular stage. In the present case, beta-catenin expression was observed in the cytoplasm of epithelial cells, which rahter resembled to the lung in alveolar stage. In 2014, Onoda T, et al. reported a novel chromosomal rearrangement resulting in α-2-macroglobulin (A2M) and anaplastic lymphoma kinase (ALK) gene fusion in a case of FLIT. However, the present case was negative for ALK by immunohistochemistry. Immunohistochemical findings of beta-catenin and ALK of the present case suggested the pathogenic heterogeneity of FLIT.
Conclusion:
A case of FLIT in a neonate is presented with typical histopathological findings. Pathogenic heterogeneity of FLIT was suggested by beta-catenin and ALK immunohistochemistry of the case.
