KMT2A-rearranged sarcoma with unusual fusion gene CBX6::KMT2A::PYGO1

We report the case of a 47-year-old man with a spindle cell tumor arising from the subcutaneous tissue of the right anterior chest. The tumor harbored an unusual novel fusion gene,CBX6::KMT2A::PYGO1. Histologically, the tumor consisted of proliferating spindle-shaped cells with uniform nuclei, which varied in cell density and the amount of intervening collagen fibers. After 2 years and 8 months without postoperative treatment, the patient showed no recurrence or metastasis. Although highly likely irreproducible, tumors with theCBX6::KMT2A::PYGO1 fusion gene were morphologically somewhat different from those containing theYAP1::KMT2A::YAP1. This suggests thatKMT2A rearrangements with fusion gene partners different fromYAP1 result in purely spindle-shaped cell tumors that produce collagen fibers.
Source: Virchows Archiv - Category: Pathology Source Type: research