A locally advanced PML::JAK1 myofibroblastic sarcoma arising in the neck

A 54-year-old male patient presented with a painful right cervical mass encasing the common carotid artery. Histologically, the tumor consisted of polygonal to spindle-shaped cells with mild nuclear atypia and low mitotic activity (0-1/10 high-power fields). No myxoid stroma or necrosis was identified, and desmin expression was patchy. GenMineTOP, a dual DNA-RNA comprehensive genomic profiling system, revealed a PML exon 7-JAK1 exon 5 fusion. The tumor was surgically unresectable because of circumferential encasement of the right common carotid artery. After radiotherapy followed by doxorubicin chemotherapy, no distant metastases developed during 17 months of follow-up. PML::JAK1 myofibroblastic sarcomas have previously been reported in four abdominal cases, most of which showed aggressive behavior. This cervical case broadens the anatomic spectrum of PML::JAK1 myofibroblastic sarcomas to include the head and neck region and further expands their morphologic spectrum.