KAT6B and neoplasm: In detail, core KAT6B/A::KANSL1 cluster tumours consisted of either a diffuse cellular population of ovoid cells that mimicked an endometrial stromal tumour, but contained scattered thick-walled vessels, or showed a spindle cell pattern (whorled growth pattern) with fibrous to fibromyxoid stroma and prominent capillary network (pericytoma-like) with bland cytology (Fig. 2a-d).