Primary pulmonary myxoid sarcoma with EWSR1-CREB1 fusion: a case report and review of the literature.

BACKGROUND

Primary pulmonary myxoid sarcoma (PPMS) is an extremely rare lung sarcoma that is characterized in most cases by recurrent balanced chromosomal translocation t(2;22)(q33;q12) leading to the oncogenic fusion gene EWSR1-CREB1.

CASE PRESENTATION

We report a case of PPMS with molecular confirmation using fluorescence in situ hybridization (FISH) and DNA sequencing in a 45-year-old female patient. Computer tomography (CT) scanning revealed a peripheral circumscribed solid mass of 2.1 × 2 cm in the right lung superior lobe. Histologically, the tumor cells ranged from stellate, polygonal to chondrocyte-like or physaliferous-like, forming reticular network of delicate lace-like cellular strands and cords in abundant myxoid stroma. The tumor cell immunophenotype was positive for vimentin, EMA and negative for CK-pan, TTF-1, CAM5.2, S-100, calponin, SMA, desmin, ALK, CD31 and CD34. Molecular analysis demonstrated EWSR1-CREB1 gene fusion in this tumor. During 38 months of follow-up, the patient was alive with no clinical or radiological evidence of recurrence or metastasis.

CONCLUSION

PPMS is a rare low-grade sarcoma with distinct histological and genetic features. We add another case to the literature of this rare tumor and report for the first time occurrence of chondrocyte-like and physaliferous-like tumor cells in this tumor, thus enriching its morphologic and cytologic spectrum.