Cutaneous melanocytic tumour with ACTB::MITF translocation

Background: Tumours driven by MiTF-family transcription factors such as MITF, TFE3 and TFEB can look remarkably similar under microscope, even though they represent biologically different entities. PEComas, for example, show both melanocytic and smooth muscle features and are linked to TSC1 or TSC2 alterations. 1 Recently, a subset of cutaneous melanocytic tumours driven by MITF translocations, such as ACTB::MITF and MITF::CREM- has been recognised, and these mimic PEComas morphologically and immunophenotypically. 2,3