A case of <scp><i>FN1</i></scp>‐fused calcified chondroid mesenchymal neoplasm of the hand with novel <scp><i>FGFR3</i></scp> partner gene
Natalia Georgantzoglou, Guomiao Shen, George Jour, Konstantinos Linos
Abstract
Calcified chondroid neoplasms with FN1::FGFR1 or FGFR2 fusions constitute a recently described category of mesenchymal neoplasms mostly encountered in the extremities and temporomandibular joint. Herein, we report a case of FNI1-fused calcified chondroid neoplasm of the hand with a novel FGFR3 fusion partner. The tumor exhibited a multilobulated growth pattern composed of epithelioid cells embedded in abundant stroma with myxoid, chondroid, and fibrous areas and scattered osteoclast-like giant cells. RNA sequencing revealed an in-frame fusion between Exon 31 of FN1 and Exon 3 of FGFR3, which was subsequently confirmed by reverse transcription-polymerase chain reaction. Our findings expand on the spectrum of potential fusion partners in FN1-fused calcified chondroid neoplasms.