The diagnosis of soft tissue tumors often arises in the dermis or subcutis is frequently challenging mainly for the superficial, inadequate samplings in many skin biopsies, and closely mimic cases such as melanoma and carcinoma. Therefore, a combination of traditional histopathology, as well as immunohistochemical and molecular genetic studies are recommended. ^1-7

 Cutaneous mesenchymal tumors that rarely occur will not be covered specifically in this section, but more comprehensive genetic details will be available in the WHO 2020 Soft Tissue and Bone Tumors. Here, we will focus on unique histological or molecular features that are unique to, or have a predilection for, the skin. The most common benign mesenchymal tumors are superficial and < 50 mm deeper with lipomas, dermatofibromas (fibrous histiocytomas), vascular or smooth muscle lesions, and nerve sheath tumors have the most frequent. Cutaneous sarcomas represent a relatively rare subset of tumors, far outnumbered by carcinomas, except for dermatofibrosarcoma protuberans, which has its peak incidence in middle-aged adults.

Recently, emerging tumor types can occur in superficial locations and harbor gene fusions e.g. nested glomoid neoplasm with GLI1 alterations; clear cell tumor with melanocytic differentiation and ACTIN::MITF, CRTC1::TRIM11 and MITF::CREM, EWSR1::SMAD3 -rearranged fibroblastic tumor, PLAG1-rearranged fibroblastic tumor, superficial ALK-rearranged myxoid spindle cell neoplasm and NTRK-rearranged spindle cell neoplasms. ^4,6,7