Epithelial Elements in Superficial Angiomyxomas: Mimicry of Adnexal Development and Mesenchymal-To-Epithelial Transition

The study examined 43 cases of superficial angiomyxomas (SAM) to explore the nature of epithelial elements present. It found that 46.5% of cases contained adnexal epithelial elements, such as immature hair follicles, which mimicked embryonic hair follicle development. These elements were associated with vimentin- and S100A4-positive stromal cells. The study identified PRKAR1A loss in SAM myxoid cells, contributing to aberrant eccrine ductal epithelium branching through mesenchymal-to-epithelial transition (MET), although MET was not involved in hair follicle epithelial growth. The findings suggest a complex interaction between mesenchymal and epithelial components in SAM, with implications for understanding Carney's complex and related pathologies.